# Ignition circuit help



## stevehuckss396

I was hoping one of you electronics Guru's might be able to analize this circuit and tell me if it can be triggered by a hall sensor. The circuit was designed to upgrade using existing points. The ignition comes in kit form for 22 bucks + postage. I was hoping I could use it with a hall effect on my next engine because the modern CDI units wont do what I want/need them to do.
If it cant be used with a hall sensor, can it be modified to work with it? I have a round PCB about 3 inches in diameter to build the circuit.
Thanks in advance!!


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## Herbiev

Yes it can. Hall effect is just a switch operated by a magnet. Just connect sensor in series to input and it should work fine.


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## MuellerNick

> Hall effect is just a switch operated by a magnet.



A switch operated by a magnet would be a reed switch.
Hall effect

Nick


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## Graham

Hi Nick,
A reed switch is a mechanical device ( too slow for an ignition system) hall effect is solid state and so triggers much faster.
I tried to use a reed switch some time ago and couldn't get it to work, it might be OK on a very slow running engine though.
Graham


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## MuellerNick

> A reed switch is a mechanical device



We both know, Herbie didn't.
Recently, I looked how fast reed switches can be, and I was amazed. Up to 300 Hz!
That would be 18000 RPM. Certainly needs some tinkering, reading the data sheet and picking the right one.


Nick


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## Graham

Hi steamer,
Have a look at 5 bears ignition systems, there is a brilliant circuit there ( the last one on the list I think) it uses a darlington pair transistor.
Only one transistor and one resistor very simple to make and a very hot spark. I have this running with a hall effect on a couple of single cylinders one 4 stroke and one 2 stroke.


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## Graham

Nick, I stand corrected.


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## stevehuckss396

_Thanks everyone! I will look at the 5 bears site pronto!_


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## jasonh

The essential part of a hall effect device is a piece of semiconductor that has a current flowing through it. In the presence of a magnetic field charge separation within the semiconductor leads to a voltage across the device in a direction transverse to the current. Manufacturers generally integrate supporting circuitry around the hall effect device to make it easier to use - typically more switch like.

Could you use a hall sensor in that circuit in the place of simple points? If the hall sensor in question has good switch-like characteristics it might work. ie- high/low, reasonable forward current. More typically you'll see a hall sensor connected to the base of a transistor or an op-amp input.

http://www.electronics-tutorials.ws/electromagnetism/hall-effect.html


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## Herbiev

Herbie did know. Perhaps I should have said solid state switch operated by a magnetic field instead of switch. I am sure most members with a basic knowledge of these devices would understand what I meant. Having worked as a telecommunications technician for over 40 years I am pretty familiar with all switching devices. The question was could it operate the above circuit? I believe I answered that Nick !!
Steamer you will find when you purchase one of these devices they usually come equipped with a small cylindrical permanent magnet with poles clearly marked


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## stevehuckss396

Well!  My ignition circuit is a failure or should i say my coil is a failure. I am getting a very weak spark if any. I am thinking the coil might not be designed for this type of circuit. I wired the coil to ground and just shorted and unshorted the coil wire and I get slim to none. I tried a 66 caddy coil and got spark.

Do I need a CDI ahead of the coil. Could the primary winding need more than 12V to get a good spark. It seams like I have the same problem as Keith5700 and his V8. I think we might have used incompatable coils.


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## canadianhorsepower

Steve , you should try it with a capacitor between the coil  could be that your pulse is so short
or week that your coil is not totaly loaded


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## canadianhorsepower

Steve forgot to ask what do you have on pin 1,2,3,4 if it's what I think you can't drive this with a hall sensor


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## Lakc

Whats the resistance of your coil primary and secondary winding, check the caddy coil too.


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## canadianhorsepower

Lakc said:


> Whats the resistance of your coil primary and secondary winding, check the caddy coil too.


 
good question, this was my next one I whent in my shop today and tried
a few thing. I think that to many issue is causing many heart breaking not
starting engines. I build the (5bears ign # tim6 with the NTE2329 I had in stock) with an hall effect sensor, output fine on the scope. Then just to put some spice on french fries instead of driving a coil I whent for a DC motor
with permanent magnet, close enought to a coil. I could go up to 100khz 
before I had any bad fluctuation on the scope, change resistor value on base
and back solid to105K after that alot of noise and that was it. I must tell you that the motor got EXTEMELY HOT:fan::fan:
This diagram works for sure.
so if we go around all the math your primary cant be more then 30 ohms
hope it help


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## Lakc

Im thinking those snowmobile coils might be high primary resistance magneto coils. In which case I gotta whip up another test CDI on a round circuit board...


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## dsage

The circuit you posted is a poor variation of the "old school" TIM circuit. A hall sensor in theory will activate it but the resistor values on the front end are pretty low value and depending on the sensor it might not be able to drive the circuit and/or may damage the sensor. The problem with all of the original TIM circuits is the output transistor breakdown voltage. In order for a coil to work properly you must not supress the kickback voltage generate on the primary side of the coil when the "points" open. When you use conventional points there is no problem since the points gap is quite large.
In the case of the TIM circuit the transistor breakdown voltage is perhaps (unchecked for the particular transistor) 150volts at most. This will limit the seconday Hi voltage to 150v x the turns ratio of the coil. Typical turns ratios are about 100:1 therefore the secondary will only get to 15kv. That's probably more than enough for a model engine but you can do better.

Try my circuit below. It has the following improvements:
1. The front end is designed for a Hall sensor.
2. The first stage does not sit around consuming a lot of power when the engine is not running. The circuit you presented consumes considerable power just sitting there doing nothing.
3. A big problem with all of the TIM circuits was that it was possible for the engine to stop with the ignition activated which could (usually did) burn out the coil and or transistor or both. This circuit will not do that.
4. Most important is, this circuit uses a proper IGBT transistor to drive the coil. One that is made specifically for this purpose for automotive ignition systems. It has a very high breakdown voltage.
5. A little extra benefit is the LED which blinks when the Hall sensor is activated so you can tell if there is activity.
6. The input circuit can be run on the same 12v as the rest of the circuit but need not be. Just be sure the ground is common to both supplies.
7. And the best part - the IGBT is a logic level input device so, if you are so inclined you can elminate the front end altogether and drive the IGBT base with a microprocessor or logic chips.

Note that the symbol for the IGBT transistor is not precise. It's drawn like it is to make if familiar to the original circuit. The IGBT is a TO220 device so you'll need to consult the spec sheet to get lead orientation.

With a little ingenuity you should be able to use your existing circuit board by leaving out components and perhaps cutting traces and adding jumpers.


[EDIT Feb. 22 2013]
Updated drawing. I had the wrong part number variant for the IGBT transistor. Sorry. All is correct now.

Sage


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## jgedde

dsage said:


> The circuit you posted is a poor variation of the "old school" TIM circuit. A hall sensor in theory will activate it but the resistor values on the front end are pretty low value and depending on the sensor it might not be able to drive the circuit and/or may damage the sensor. The problem with all of the original TIM circuits is the output transistor breakdown voltage. In order for a coil to work properly you must not supress the kickback voltage generate on the primary side of the coil when the "points" open. When you use conventional points there is no problem since the points gap is quite large.
> In the case of the TIM circuit the transistor breakdown voltage is perhaps (unchecked for the particular transistor) 150volts at most. This will limit the seconday Hi voltage to 150v x the turns ratio of the coil. Typical turns ratios are about 100:1 therefore the secondary will only get to 15kv. That's probably more than enough for a model engine but you can do better.
> 
> Try my circuit below. It has the following improvements:
> 1. The front end is designed for a Hall sensor.
> 2. The first stage does not sit around consuming a lot of power when the engine is not running. The circuit you presented consumes considerable power just sitting there doing nothing.
> 3. A big problem with all of the TIM circuits was that it was possible for the engine to stop with the ignition activated which could (usually did) burn out the coil and or transistor or both. This circuit will not do that.
> 4. Most important is, this circuit uses a proper IGBT transistor to drive the coil. One that is made specifically for this purpose for automotive ignition systems. It has a very high breakdown voltage.
> 5. A little extra benefit is the LED which blinks when the Hall sensor is activated so you can tell if there is activity.
> 6. The input circuit can be run on the same 12v as the rest of the circuit but need not be. Just be sure the ground is common to both supplies.
> 
> Note that the symbol for the IGBT transistor is not correct but it's displayed as it is to make if familiar to the original circuit. The IGBT is a TO220 device so you'll need to figure out the proper lead orientation.
> 
> With a little ingenuity you should be able to use your existing circuit board by leaving out components and perhaps cutting traces and adding jumpers.
> 
> Sage


 
A reasonable circuit.  But, your coil is wired "upside down."  The return side of the HV should NOT be connected to the collector of the transistor...

I like the way you've AC coupled the Hall sensor so the battery doesn't get drianed or the coil burned out if the crankshaft is left in the triggered position.

John


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## stevehuckss396

Lakc said:


> Whats the resistance of your coil primary and secondary winding, check the caddy coil too.



The primary was 0.6 ohms. Didn't check the secondary. I will check all of the coils and post back tomorrow.


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## stevehuckss396

canadianhorsepower said:


> Steve forgot to ask what do you have on pin 1,2,3,4 if it's what I think you can't drive this with a hall sensor




I don't have pins 1-4, I only have a black and red wire on the primary side.


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## stevehuckss396

Keep in mind here that I wasn't driving the coil with electronics. I was simulating the points by making and breaking the hot wire leading to the coil.


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## Lakc

jgedde said:


> A reasonable circuit.  But, your coil is wired "upside down."  The return side of the HV should NOT be connected to the collector of the transistor...


Ground switching or feed switching, the current differences of 1 ohm to the 400v+ primary kick are negligble. The secondary doesnt find ground through the transistor, its ground is the primary, so thats acceptable.


> I like the way you've AC coupled the Hall sensor so the battery doesn't get drianed or the coil burned out if the crankshaft is left in the triggered position.
> 
> John


There will still be current flowing through the primary, so the capacitor just provides some extra isolation for the hall to avoid self destruction. It is a neet way to do that. 

Steve, let me know what you find out with those resistances. I just found my notes and source code for my cdi, and if I cant debug that in time I can whip up an easy PIC microcontroller circuit to get you moving. I should have plenty of parts on hand, and there is always Electronic Connection or Able Electronics locally. Whats the interior dimensions of your box we have to work with?


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## stevehuckss396

Lakc said:


> . Whats the interior dimensions of your box we have to work with?



I will provide a drawing tomorrow as well. Thanks for the help.


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## canadianhorsepower

stevehuckss396 said:


> I don't have pins 1-4, I only have a black and red wire on the primary side.


 
where is your input signal connected to


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## stevehuckss396

canadianhorsepower said:


> where is your input signal connected to




Red wire, black is ground?


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## canadianhorsepower

> [Red wire, black is ground?/QUOTE]
> are you using the circuit shown here at the bigining, or something else????
> what are you using for input signal points? hall sensor/ opto coupler?


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## cfellows

I may be dead wrong, but I think one problem with these small coils is that they don't have much resistance in the primary winding.  Jerry Howell recommended using coils with at least 1 ohm or more primary resistance with his tm6 inition circuit.  

I think the low resistance is indicative of not many windings on the primary requiring more current to get a decent spark.  Hence, you may need more amps to the primary of the coil.

Chuck


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## canadianhorsepower

Cfellows, It's hard to judge this one that's why I asked Steve witch circuit is he using
the digram on this post. The output transistor is a  TIP 162 an with a to247 case same thing
that bear is using with his TIM6 (nte 2329) But Steve have a TO-3 case this would be the TIM 7 circuit.
If that's the case no way he can drive that transistor with a hall effect


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## dsage

jgedde:

The connection of the coil is correct in my diagram (despite what you think concerning "upside down" - whatever that means).
There are only 3 wires on a (automotove) coil  + / - and HV.
Inside the coil the low side of the HV output is hard-wired to the coil negative lead. So it's exactly as drawn. As mentioned by someone else the HV is looking for a return to it's low side not circuit ground. 
 The circuit drives the coil low side just like a conventional kettering ignition. It's always easier to implement a low side driver than a high side driver.

Having said all of that:

Why not just scrap all this TIM crap and the big coil required  and just purchase one of the single spark CDI units from here:

http://www.cncengines.com/ic.html

about halfway down the page in the center. They work really well and the tiny coil is on the board. The whole thing is only about 1-1/2" square. Runs on 4.8v of AA rechargeable batteries as well. You can hide it all and do away with the ugly big box typically used to sit your engine on to hide the coil and battery.

Sage


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## dsage

Lakc:

There is a big difference in the current consumption of the original circuit and the one I presented when the circuits are sitting around doing nothing. The original circuit consumes almost 250ma. Mine only consumes 6ma. There is no coil primary current when the circuit is not active.

I digress.

Just order one of the CDI systems and be done with all the TIM stuff.

Sage


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## canadianhorsepower

dsage said:


> I digress.
> Just order one of the CDI systems and be done with all the TIM stuff.
> 
> Sage


 
Thanks for your input but this is why Steve didnt go that route. The supplier told himhis system cant do it
please reed this
cheers


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## stevehuckss396

canadianhorsepower said:


> [Red wire, black is ground?/QUOTE]
> are you using the circuit shown here at the bigining, or something else????
> what are you using for input signal points? hall sensor/ opto coupler?
> 
> 
> 
> 
> I bypassed the entire circuit. I was trying just the coil and a battery.
Click to expand...


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## canadianhorsepower

stevehuckss396 said:


> canadianhorsepower said:
> 
> 
> 
> I bypassed the entire circuit. I was trying just the coil and a battery.
> 
> 
> 
> 
> 
> witch circuit are you using or where you using without having your expectation?
Click to expand...


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## stevehuckss396

OK here is the deal


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## stevehuckss396

dsage said:


> Lakc:
> 
> 
> Just order one of the CDI systems and be done with all the TIM stuff.
> 
> Sage




I would need to order 2 of them at 60 bucks each. Then mount them somewhere. I understand what you are saying but i think this way is worth trying. It is going to look so much better if I can get this going.


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## canadianhorsepower

ok thats fine for the coil
IT"S A twin coil one input two simultanious output????
so far so good
were is a copy of the diagram you are using??


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## stevehuckss396

canadianhorsepower said:


> stevehuckss396 said:
> 
> 
> 
> witch circuit are you using or where you using without having your expectation?
> 
> 
> 
> 
> 
> I don't understand what you are asking.
> 
> I did not try to use any thing except the coil and a battery.
> 
> Negetive coil and battery hooked together
> 
> Positive of battery to positive of coil simulating points. Touch, let go, touch, let go.
Click to expand...


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## stevehuckss396

This is the circuit I built. I did not see the point in trying the circuit if the coil won't spark without it. I used this circuit with a 66 caddy coil and it worked just fine.


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## canadianhorsepower

your electronic circuit with that huge transistor mounted on your casing 
did you try it with these coils?


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## stevehuckss396

canadianhorsepower said:


> your electronic circuit with that huge transistor mounted on your casing
> did you try it with these coils?



No, If the coil wont spark with the battery it isn't going to spark with the transistor in series with it. I would like to get the coil figured out before I hook up the electronics. I hooked up the caddy coil to the battery and it sparked fine.


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## canadianhorsepower

stevehuckss396 said:


> This is the circuit I built. I did not see the point in trying the circuit if the coil won't spark without it. I used this circuit with a 66 caddy coil and it worked just fine.


  with out having any part number no one can help you.the voltage divider between 47k and 680 is not enought to saturate the transistor itself


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## canadianhorsepower

you must also take into consideration coils in 1966 and now are not quite the same
at that time 12KV was hight now 50KV is almost the standard


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## stevehuckss396

canadianhorsepower said:


> with out having any part number no one can help you.the voltage divider between 47k and 680 is not enought to saturate the transistor itself




Works fine with the other coil. Here is what I used. 

View attachment ignitionDevice.pdf


View attachment ignitionPNPDevice.pdf


View attachment ignitionDeviceHallSensor.pdf


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## canadianhorsepower

thanks I'll get back to you soon got to chat with my calculator
do you have any resistance value of the coil you were using with this ???
thanks


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## stevehuckss396

canadianhorsepower said:


> thanks I'll get back to you soon got to chat with my calculator
> do you have any resistance value of the coil you were using with this ???
> thanks




Look back at reply #34. I posted a pic with the coil readings. Keep in mind there is no connection between primary and secondary windings.


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## Mosey

Strong opinions, here.
Wonder?


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## Lakc

stevehuckss396 said:


> No, If the coil wont spark with the battery it isn't going to spark with the transistor in series with it. I would like to get the coil figured out before I hook up the electronics. I hooked up the caddy coil to the battery and it sparked fine.



Not exactly, if the coil draws more amperage then the caddy coil it will be more prone to arcing when you break the connection. Arcing slows down the collapse of the magnetic field which produces a weaker spark. It might actually work. 

Whats the depth of your enclosure?


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## stevehuckss396

The current enclosure has .625 from the cover to the board mounts. Back of the board to the cover = .625

I can cut down the mounts to give .750 if need be.


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## dsage

Steve:

A couple of things:

The output of those dual output coils is between the two high voltage leads - not from either lead to ground. The high voltage travels from one HV lead to the first spark plug, jumps the gap, travels through the engine block to the other spark plug, jumps that gap and returns to the coil through the other HV lead. 

Both spark plugs fire at the same time. The one plug fires when there is no compression so it's easy to jump that gap leaving all the energy for the other plug. It's called a waste spark ignition. Because the spark is sort of wasted on one cylinder at a time. Makes for a simple ignition though.


To test this simply - on the bench - put a spark plug on the one HV lead and use a clip lead to join the other HV lead to the threads of the plug.
I'll bet it works then.
The engine block is just a current path with this setup. It need not be grounded. (but it can be). It is not required.

As for your circuit the 680 ohms and 47k is fine on the input transistor but the other 680 ohm resistor on the power transistor is not sufficient to drive the power transistor with the coil you are using.

I didn't look up the actualy specs for the transistors you are using but generally speaking signal transistors and general purpose power transistors are similar.

The calculations go (roughly) like this.
For the input transistor:
12v/680 ohms = 17ma
The input transistor probably has a gain of about 150 so the transistor will be driven hard enough to supply 150 x 17ma = 2.6A but it will never need to do that nor could it. Suffice to say that that part of the circuit is fine.


For the power output transistor you still have the other 680ohms and 12V which is 17ma. The power transistor probably only has a gain of at best 50.
So 17ma x 50 = 0.85A.
Therefore the output transistor only has enough drive to supply 0.85A on its output collector.

Your coil you said was 0.8ohms so it will be trying to draw 12v. / 0.8 = 15amps. So you are way short of drive on that transistor.

You could substitute a darlington power transistor for the one you are using. A darlington will have a higher gain and will be able to drive the coil with the 680 ohm resistor. (if it is already then your fine)

If you need more help I can re-design the circuit for you.

As mentioned before an IGBT power transistor would be a better choice for all the reasons I mentioned previously and it would also work in the existing circuit.


BTW, you should not drive a coil directly across a 12V battery. In a car (back in the day) there was a ballast resistor of maybe .5 ohms to limit the current to the coil should the points stop in the closed condition.
I mentioned all of this before. It is possible for your engine to stop with the hall effect activated and therefore the coil will be stuck ON ans will likely burn out the coil and / or the transistor.
This is the one thing wrong with all the original TIM circuits.
Be careful!! or use my circuit. It's better in a lot of ways.

Sage
(Electronic Technologist - retired)


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## canadianhorsepower

> [/Look back at reply #34. I posted a pic with the coil readings. Keep in mind there is no connection between primary and secondary windings. QUOTE]





> Hi Steve, I did a few test and calls today and I have a few good answers.
> 1 even if it works you should fire your coil thrue ground and not live.
> thats an easy fix replace both transistor with the oposite ( from NPN to PNP)
> 2 the output trans your using is on the limit as far as suplying the need of this coil
> that is really more a "step up transformer" then an "inductor"
> 3 I called one of my buddy at BRP in Valcour reguarding the testting of these dual coil.
> His answer was pretty straight forward, "you have a sparks it's fine" reason beeing because
> it is fired simultaniously it has a vector effect on how mutch will go when. the fatter side will get
> it all and leaner side will get nothing. He told me that they took them out of the market for two reasons.
> Number one they were confusing to check and were very hard on the module.
> I hope it's of any help. BTW what CAD did you use for these drawingscratch.gif
> 
> cheers


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## stevehuckss396

The electronic circuits were drawn in paint. The distributor and board were done in Alibre.


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## canadianhorsepower

is this the BEST you can do:shrug:


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## stevehuckss396

So what you are saying is to connect the 2 ground straps and the circuit is complete.

Alot of info up there. I must have read it 5 times. 

I knew that both plugs fire at the same time. That is fine with me.

I know the gain is more like 300 not 50. Would that be acceptable?

I'm not worried about the coil being left on. The starter box I use has a switch on it. The motors get started and after they run I cut the power to shut them down. The ignition would never have power on it unless the motor is running.


I could always use more help. If you redesign the circuit do you think you could get this thing sparking or am I wasting my time with this thing? I know they are a pain but it looks so good on the motor.

Lakc is looking into a CDI circuit. Would the CDI circuit be a better driver for the coil and give a stronger spark? 


Well thanks for looking into this thing for me. I know how time consuming it can be diving into something like this.


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## stevehuckss396

canadianhorsepower said:


> is this the BEST you can do:shrug:



Whats wrong with paint? Makes good drawings and it's free.


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## dsage

Candianhorsepower:

You are completely wrong !!

You cannot correct Steves circuit by simply swapping NPN and PNP devices. It will NOT work.

Steve:

Sorry I didn't check your component PDF's first. Your output transistor is an excellent choice. It has a gain (hfe in the specs) of 300, so with the 680 ohm resistor should have enough drive to supply 5amps to the coil. This is more than enough (even though the coil will be trying to draw 15amps. It also has a high breakdown voltage so it won't be supressing the primary kickback. (That;s why it's designed for ignition circuits).

You need to make a couple of small changes to your circuit though...

1. Move the coil to be in the collector circuit - between the collector and 12V. The way it is it will be difficult for the drive to the output transistor to fully turn it on.

2. Ground the emitter (the one with the arrow - where the coil is in your diagram now).

3. Add a 1k resistor from the base of the power transistor (also where the 680 connects) to ground. This will ensure the transistor turns off properly.

4. For safety please also add a low value high wattage resistor in series with the coil. I'd say 1ohm 10watt wire wound ceramic part should do it. (like the old school cars had - ballast resistor)


Sorry I don't have the ability to redraw your circuit at the moment.

For the benefit of others please redraw it like I mention here. (so I can see and doule check it too)

Also go back a couple of posts and see my note about how the coil needs to be connected to the plug(s) and how to test it on the bench. 

Let me know if you need further help or don't understand my instructions.

Thanks


Sage


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## dsage

Steve:

Sorry I didn't see your post #53 asking about the plug wiring.

I'm pretty sure what you have is a dual output coil used for waste spark ignition. I hope I'm right on this and haven't wasted a lot of effort typing this.

There are no grounds necessary on the spark plug side of things.
I recommend you test it as suggested on the bench to be sure and so you can see the spark energy Sorry for the crude diagrams below.


With one plug connect like this:

HV --plug -------jumper wire-------HV

IF you want to test with two plugs:

HV --plug------jumper wire -----plug---HV

The jumper wire will need to be clipped to the threads of the two plugs and the HV leads connected as normal to the tops of the plugs.

In the engine, screw in the plugs into the heads and connect a HV lead to each. The plugs will be connected together because they are both screwed into the metal heads. The block / heads do not need to be grounded (although it won't hurt anything it is not necessary). 
The spark is looking for a path between the two HV leads. NOT to ground. What it sees is two spark plug gaps in series between the HV leads. The heads / block is just the connection between the plugs.
(obviously the heads must be electrically connected and not insulated by head gaskets - very unlikely as bolts will make the connection).

I know it sounds odd but you have to get your head around the fact that the heads / block are not supplying a ground for the spark, just an electrical connection between the two plugs.

Hope this helps.

If I missed answering anything let me know.

BTW. Now that I see the nice job you have done, (as usual) I would recommend continuing with what you have. If the coil is good, the arrangement will be fine. No sense starting over. Using a CDI unit with a conventional car coil will result in excessive HV which may cause you problems on a model sized engine. 7kv is plenty on our small plugs. 60kv on the other hand will be looking for all kinds of places to jump.


Sage


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## Lakc

stevehuckss396 said:


> So what you are saying is to connect the 2 ground straps and the circuit is complete.


As long as both plugs are screwed into the same motor your fine 



> Lakc is looking into a CDI circuit. Would the CDI circuit be a better driver for the coil and give a stronger spark?


I have one, needs some tweaking  I think we can even cram it into the space you have as well. I actually had originally programmed in a pinswap so it would fire a transistor instead of an SCR for the CDI. As to which is better, that debate is similar to the Apple-PC one and we wont go there


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## canadianhorsepower

stevehuckss396 said:


> Whats wrong with paint? Makes good drawings and it's free.


 Sorry I was trying to joke a little. it's funny  with all your knowledge and programs seeing you using paint really surprise me


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## canadianhorsepower

Sage, [QUOTE*]Candianhorsepower:

You are completely wrong !!

You cannot correct Steves circuit by simply swapping NPN and PNP devices. It will NOT work[/QUOTE*]

Hold on a minute before doing bold comments like this one. I know damm well that a "SIMPLE SWAP" would not work that's
what I teach. Instead of trying to look like a smart ass and add a full page of infor that are not neede at this time I pointed out
some change that could be done. If you read the complete post you would realize that even if it doesn't satify you it's a working circuit.
I'm trying to give Steve as many info as I possibly can and from there he can decide what to do.

_are you the same one that wrote on post #30 *I DIGRESS JUST ORDER ONE OF THE CDI AND BE DONE WITH ALL THAT TIM STUFF*_
_IT WOULD HAVE BEEN NICE IF YOU WOULD HAVE STICK TO YOUR WORDS INSTEAD OF BLASTING ME OFF FOR NO REASON_


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## stevehuckss396

canadianhorsepower said:


> Sorry I was trying to joke a little. it's funny  with all your knowledge and programs seeing you using paint really surprise me



I drew that circuit along time ago before I had access to any of the fancy drawing programs.


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## stevehuckss396

dsage said:


> Steve:
> 
> I'm pretty sure what you have is a dual output coil used for waste spark ignition. I hope I'm right on this and haven't wasted a lot of effort typing this.
> 
> I know it sounds odd but you have to get your head around the fact that the heads / block are not supplying a ground for the spark, just an electrical connection between the two plugs.
> 
> Using a CDI unit with a conventional car coil will result in excessive HV which may cause you problems on a model sized engine. 7kv is plenty on our small plugs. 60kv on the other hand will be looking for all kinds of places to jump.
> 
> 
> Sage



No you have not wasted your effort. It is in deed a wasted spark ignition. 

I am on board with how the circuit works. The engine is just acting as a jumper between the 2 ground straps on the plugs. I considered that when I was testing.

All my ignition components are full size. The plugs are NGK V-Power. I had a few spares from a hotrod that I no longer have. This engine is my old air compressor with 2.625 bore. It has 1.175 inch valves with full size plugs.

Again thanks. I am in the process of redrawing and should post it up real quick here.


----------



## stevehuckss396

Here is the new circuit ALA Dsage.

Now that it is redrawn I will need to make a new board. If I'm going to do that, should I lower the value of R3 to increase current flow in the coil primary?

Yes CHP! I did it in paint!Rof}Rof}Rof}


----------



## stevehuckss396

I have the new board layed out. I won't do anything with it until Lakc weighs in with the CDI circuit. I will most likely build and test both. If they both work I will go with the one with the most spark and keep the other for an emergency board. Nothing ever seems to go wrong until there is a crowd of people watching.


----------



## Les_S

Absolute newby to this forum and I certainly don't want to upset anybody but I beleive, after looking at your schematic, that you have your 2N3906 transistor upside down. Emitter should connect to power supply positive, not the collector.
Best regards,
Les


----------



## canadianhorsepower

Hi Steve, "the artist"
 I went to Princess to get a compressor head twin like the one posted
on the other blog that you opened. I started reading comp head specs and
then eek. The MAX RPM is 1900 RPM is it the same for you or is it pure
warning because of the flywheel size What's your opinion on this matter.

Did you mount your hall inside and using the shaft for the trigger


----------



## jack620

Les_S said:


> Absolute newby to this forum and I certainly don't want to upset anybody but I beleive, after looking at your schematic, that you have your 2N3906 transistor upside down. Emitter should connect to power supply positive, not the collector.
> Best regards,
> Les



I think so too.  But I don't think turning it the right way around will work either.  Shouldn't it be an NPN transistor?


----------



## Les_S

A lot of work has gone into this design so again, I certainly don't wish to upset anybody. The circuit will work with the 3906 turned around. When the hall effect switch is turned on by the magnet, the 3906 will be forward biased which will pull the 3906 collector up to nearly 12 V which will in turn forward bias the BU941 and energize the coil building up a magnetic field. Spark will actually occur when the BU941 turns off and the field collapses.
Best regards,
Les


----------



## stevehuckss396

canadianhorsepower said:


> Hi Steve, "the artist"
> I went to Princess to get a compressor head twin like the one posted
> on the other blog that you opened. I started reading comp head specs and
> then eek. The MAX RPM is 1900 RPM is it the same for you or is it pure
> warning because of the flywheel size What's your opinion on this matter.
> 
> Did you mount your hall inside and using the shaft for the trigger



I believe the flywheel is the limiting factor. Because it is cast and real heavy it will come apart real easy. If it were billit and balanced I bet that number would increase to 6-8K

I have a disk on the tail of the camshaft that has the magnets in it. The sensor is mounted to the back of the junction box and the magnets fly in front of it. There are 2 magnets 135 degrees apart. Here is what it would look like if the jbox were see thru. You can see the circuit board and the disk behind it. The sensor gets glued to the back of the jbox behind the magnet disk.


----------



## stevehuckss396

Les_S said:


> Absolute newby to this forum and I certainly don't want to upset anybody but I beleive, after looking at your schematic, that you have your 2N3906 transistor upside down. Emitter should connect to power supply positive, not the collector.
> Best regards,
> Les



Are you sure? The data sheet shows all the test circuits with the collector positive.


----------



## Les_S

Hi Steve,
Let me first say that I really admire your work!

I am sure that the 3906 in your drawing is upside down but I can see how the datasheet can be confusing.

Note the waveform used for the delay and rise time test. The test signal starts @ +.5V at which time the transistor would be off. Then the test signal goes to -10.6V at which time the transistor would turn on because the emitter is setting @ 0V which is way more positive than -10.6V. Same situation with the duty cycle test. For a PNP transistor, the emitter has to be more positive than the base to turn on. For a NPN transistor the base has to be more positive than the emitter to turn on.

Hope that helps. The test circuits show a means of testing transistor operating characteristics. They are not application circuits.

Best regards and I can't wait to see your compressor run!

Les


----------



## stevehuckss396

How about this one? I also flipped it on the circuit board drawing.


----------



## Les_S

That will work. There are a lot of smart folks on this forum and I don't claim to be one of them but the electrons have had their way with me for many years so I'll be happy to help if I can.
Les


----------



## stevehuckss396

Les_S said:


> That will work. There are a lot of smart folks on this forum and I don't claim to be one of them but the electrons have had their way with me for many years so I'll be happy to help if I can.
> Les



Thank you very much. My original drawing was drawn correctly and somehow I turned it around on the new one.


----------



## dsage

Hi Steve:

The circuit in post #71 is almost correct. I would suggest a couple of more changes / corrections.

1. The 0.5 ohm resistor should be in series with the coil on the collector side and the emitter should be grounded....

BUT !!

After having another look at the spec sheet. The power transistor has about a 2 volt drop across it when turned on (Vce under certain conditions). Considering that, with the 0.5 ohm resistor in the circuit the coil may only see 6 volts. 
So on further consideration (and considering the fact that you will be diligent in turning off the ignition if the engine stalles etc. etc) let's remove the 0.5 ohm resistor from the circuit and ground the emitter.


2. As you mentioned the 680 ohm resistor could be reduced to say 470 ohms for a bit more drive to the transistor. There is a limit how low you can go here since the 2N3906 has a current limit as well.


It's difficult to get all the values correct just from spec sheets but I think you will be close. I would activate the circuit and take a few very quick voltage measurement. One being how much voltage is actually across the coil and across the transistor.

Did you try the coil / plug circuit testing on the bench to confirm the coil works as expected ??


Canadianhorsepower:

To clarify - What you wrote was

Quote:

"Hi Steve, I did a few test and calls today and I have a few good answers.
1 even if it works you should fire your coil thrue ground and not live.
thats an easy fix replace both transistor with the oposite ( from NPN to PNP) 

I'm not sure how you read the above but to me that says you can swap the type of transistors and your good to go. Which is not correct.
If there was more involved (which there is) then you should have explained further. You must keep in mind that you are giving instructions to people that know a lot less electronics than you (or me).

This is why I try my best to explain things thoroughly and burn up a lot of space and time doing so. (sorry for that).


Sage


----------



## stevehuckss396

Ok now you went and used the B word.  If the IGBT would be better what IGBT should I look at? If I do change to a IGBT what resistors will need to change and to what values? Remember I am starting from scratch so I would perfer to design this thing to the best it can be with the most current information. As long as I can fit it all into the box. I would have no objection to changing it up if the outcome will be a better design.

No I did not get a chance to do any testing. I did get some spark out of it when fooling with it before.


----------



## dsage

Steve:

I went back and looked at my IGBT spec and it has only marginally better voltage drop at high currents. So stick with what you have. (makes sense since the IGBT is also a bipolar transistor). 
The only thing significantly better in terms of voltage drop woud be a MOSFET but it wouldn't have the high breakdown voltage and would (like the plain old transistor in the original TIM5 circuit) supress the primary kickback and reduce the seconday output.

I think you'll be good with what you have. (as best I can tell without testing it).

I would strongly suggest you try it out on the bench even just "dead bug style" (a term used to describe cobbling it together without a circuit board) to be sure it works before you take the time to make a circuit board. Maybe you could borrow a proto board to wire it together.

Please re-draw the circuit (again) for the benefit of us all.

Thanks

Sage


----------



## canadianhorsepower

dsage said:


> Hi Steve:
> 
> The circuit in post #71 is almost correct. I would suggest a couple of more changes / corrections.
> 
> 1. The 0.5 ohm resistor should be in series with the coil on the collector side and the emitter should be grounded....
> 
> BUT !!
> 
> After having another look at the spec sheet. The power transistor has about a 2 volt drop across it when turned on (Vce under certain conditions). Considering that, with the 0.5 ohm resistor in the circuit the coil may only see 6 volts.
> So on further consideration (and considering the fact that you will be diligent in turning off the ignition if the engine stalles etc. etc) let's remove the 0.5 ohm resistor from the circuit and ground the emitter.
> 
> BTW this is another reason the IGBT transistor (I use in my circuit) would be better. It has almost no drop when properly turned on and so all the battery voltage would be available to the coil. But lets continue with your circuit.
> 
> 2. As you mentioned the 680 ohm resistor could be reduced to say 470 ohms for a bit more drive to the transistor. There is a limit how low you can go here since the 2N3906 has a current limit as well.
> 
> 
> It's difficult to get all the values correct just from spec sheets but I think you will be close. I would activate the circuit and take a few very quick voltage measurement. One being how much voltage is actually across the coil and across the transistor.
> 
> Did you try the coil / plug circuit testing on the bench to confirm the coil works as expected ??
> 
> 
> Canadianhorsepower:
> 
> To clarify - What you wrote was
> 
> Quote:
> 
> "Hi Steve, I did a few test and calls today and I have a few good answers.
> 1 even if it works you should fire your coil thrue ground and not live.
> thats an easy fix replace both transistor with the oposite ( from NPN to PNP)
> 
> I'm not sure how you read the above but to me that says you can swap the type of transistors and your good to go. Which is not correct.
> If there was more involved (which there is) then you should have explained further. You must keep in mind that you are giving instructions to people that know a lot less electronics than you (or me).
> 
> This is why I try my best to explain things thoroughly and burn up a lot of space and time doing so. (sorry for that).
> 
> 
> Sage


 
dont be sorry just don't be a smart ass or an ass hole what ever you prefer.
I NEVER MISSED LEAD SOMEONE, I WILL GIVE OPINIONS ,YOU NEED ADVICE ,THEN I WILL STEP UP AND BOW OR STAND FOR WHAT I'M TALKING ABOUT...................................YOU SHOULD TRY THIS 

I did mentionned before I don't put BS I'n my response to someone to look better then someone else. I hope you would realize that all the BS you did put so far only got THIS FORUM to a big pile of ****. Steve had a borderline 
working circuit "changing 1 resistor" would have work. Now he's starting almost from the start. Thank you:rant:
 Hope you have enought BALL'S to help ???????? Steve now that almost no one whan't to get involve in this forum:shrug:
When I whent with my cancer surgery they had special equipement to keep your scare together . maybe you should look for one that will keep your chest smaller./............. if it does not work try one for your head >>>>>>>>>>>>>>>>>


----------



## stevehuckss396

dsage said:


> Steve:
> 
> I went back and looked at my IGBT spec and it has only marginally better voltage drop at high currents. So stick with what you have. (makes sense since the IGBT is also a bipolar transistor).
> The only thing significantly better in terms of voltage drop woud be a MOSFET but it wouldn't have the high breakdown voltage and would (like the plain old transistor in the original TIM5 circuit) supress the primary kickback and reduce the seconday output.
> 
> I think you'll be good with what you have. (as best I can tell without testing it).
> 
> I would strongly suggest you try it out on the bench even just "dead bug style" (a term used to describe cobbling it together without a circuit board) to be sure it works before you take the time to make a circuit board. Maybe you could borrow a proto board to wire it together.
> 
> Please re-draw the circuit (again) for the benefit of us all.
> 
> Thanks
> 
> Sage




Give me about 30 minutes!


----------



## stevehuckss396

This is the latest.


----------



## stevehuckss396

I noticed that the IGBT is surface mount. How is the device heat sinked?  Does the board act as a heat sink?  If so it might be worth going that route rather than the remote mounted transistor. Would make things easier and in the end, cleaner looking.


----------



## canadianhorsepower

stevehuckss396 said:


> This is the latest.


 I admire your effort  and courage. if people would only stick there finger up ANY EMPTY HOLE they wouldn't side track someone asking for info:wall:


----------



## dsage

Looks good Steve:

Give it a try. Even with your oldschool car coil first just in case the coil you want to use is bad.

(I try to do my best despite the distractions )

Sage


----------



## stevehuckss396

dsage said:


> Looks good Steve:
> 
> Give it a try. Even with your old coil first just in case the coil you want to use is bad.
> 
> Sage



Okie Dokie!


----------



## canadianhorsepower

*simply want o apologize for some bad expression I have use. I guess some expression can be use in a shop but not on a public site*
Steve: If I can make any sugestion, simply purchasse a small dc motor (12volts) at radio shack and mount a small plastic plate
plate at the end then put a screw and a smal magnet 180 degree apart. You can control the speed with a small potentiometer
to simulate a distributor. I use this all the time to check circuit


----------



## dsage

Canadianhorsepower:

Good idea with the motor and magnet thing. This way you can use the actual magnet that will be used on the engine. (see below)
I've always triggered such circuits with a 555 timer oscillator but with that method you don't get the variablel dwell (circuit activation time) that you would get with the spinning magnet idea. I'll have to try that. Thanks.

On that note:
It was pointed out earlier (by someone else) that the TIM circuits with a hall sensor do not operate exactly like a conventional points type ignition. With the TIM circuit, the coil is normally de-energized, then energized for a short period of time while the magnet is in front of the sensor and then the circuit turns off again. 
The important point is that the spark occurs when the sensor is cleared not when it is activated. Therefore there will be a built in error in your spark timing by the width of your magnet. As long as you have adjustment in your timing (usually by turning the distributor) and you use a timing light this poses no problem.

The other thing is the magnet size becomes somewhat important in that at the highest RPM you wish to operate, the sensor (and the coil) must be activated for a reasonable amount of time to "charge up" properly. A couple of milliseconds should be enough and you can calculate that by observing how many degrees of rotation the magnet activates the hall sensor and figuring the activation time from deg per second at the maximum RPM. If you're a bit short just mount a slightly bigger magnet.

In my V8 the magnets are 3mm in the distributor (equiv of 6mm on the crank) so they don't need to be large. But worth some rough calculation to be sure you don't run out of spark at high RPM's.

Sage


----------



## canadianhorsepower

> [/With the TIM circuit, the coil is normally de-energized, then energized for a short period of time while the magnet is in front of the sensor and then the circuit turns off againQUOTE]
> 
> That's wright,but quick fix to this.:idea: I'm using a op amp (741) and use the input from the hall sensor and connect it to the inverting
> input pin (2) then my output (6) match the circuit. I also use a 4mm rare earth magnet . These are strong enought that i dont have to mount
> the sensor real close to the magnet.
> As for the timing marks I was turning my motor by hand and with a led where the coil goes I could see that the spark happen wright after
> the magnet pass the sensor and that work 100%


----------



## dsage

How did you arrange for the split +/- power supply for the 741 opamp?
Actually, I suppose it doesn't matter in this application that the output of the 741 won't swing all the way to zero volts when you operate it from a single supply. I guess it would work ok.

The big issue with inverting the logic so the coil is ON most of the time (instead of off) is that when it's ON it's drawing maybe 15amps. Your battery won't last long. And a lot of things get hot. It's more power efficient to have the circuit off most of the time especially on a two cylinder engine where it spends most of the time waiting for the next spark anyway. On an eight cylinder there becomes an issue at high RPM's not having enough time for the coil to "charge" up between sparks so it's just as well to leave it on.


Sage


----------



## canadianhorsepower

> How did you arrange for the split +/- power supply for the 741 opamp?


I don't understand this one???



> The big issue with inverting the logic so the coil is ON most of the time (instead of off) is that when it's ON it's drawing maybe 15amps.


your right about this one but your only going to generate a spark when you cut the magnetic field.
If we do the math for an 8 cyl at 4000 rpm = 16,000 pulse  per minutes time 60 for seconds and we geta frequency of96000 hz
I'd say that at that speed is has to be on some time to recharge


----------



## dsage

The 741 opamp requires a + supply (above ground) and a minus supply (below groound). So you'd need a minus supply for it to work properly. If you run it on a single supply (12v and ground) the opamp output will not go to zero volts. Instead it will only swing to (I've forgotten) but some low value above zero. As mentioned it probably makes little difference in this circuit. Although there are single supply opamps available and you could use one of those instead (forgot the part number).

But, a much simpler approach would be to add, yet another transistor and resistor to make an inverter on the front end. Much easier to lay out on a circuit board as well instead of that 8 pin DIP device.

Check your math. You have the 16,000 sparks per minute correct but that's only 16000/60 = 267 sparks per second, or one spark every 4ms.

As I mentioned it does become an issue for an 8 cylinder engine but for a 2 cylinder it's only 67 sparks per second or one every 15ms.

A two cylinder would not be in the same predicament until it reaches 16k RPM.

Sage


----------



## dsage

Steve:

Looking back a bit I see I missed your one liner asking about the IGBT transistor.
I goofed up my drawing part number (sort of)
The correct part number is an IRGB14C40LPBF not IRGS....
Same part but the IRGB is a TO220 tabbed variant capable of being screwed down.
I guess too many numbers and letters to get straight in my head.

Having said that for a low power application the tab(less) device would probably run cool enough to survive right on the board.

I updated the drawing in the previous post.

Thanks

Sage


----------



## canadianhorsepower

Come on [*QUOTE]The 741 opamp requires a + supply (above ground) and a minus supply (below groound). So you'd need a minus supply for it to work properly. If you run it on a single supply (12v and ground) the opamp output will not go to zero volts[/QUOTE]*
If you dont have the below ground it will go to zero but not  below ground. I can show you a picture from the scope to show it.

[*QUOTE]But, a much simpler approach would be to add, yet another transistor and resistor to make an inverter on the front end. Much easier to lay out on a circuit board as well instead of that 8 pin DIP device[/QUOTE]*
it's your choice, but single transistor are a bit old school the trend now is op amp. I'm not using 741 cause  the opamp I'm using is a 4 channel for my injection system and I'm also using it in a comparator mode

*



			Check your math. You have the 16,000 sparks per minute correct but that's only 16000/60 = 267 sparks per second, or one spark every 4ms.
		
Click to expand...

*_no no no my math are fine Revolution Per Minute will always be 60 time less then revolution per seconds_
_their is 3600 seconds in one hour so take your RPM multiply it by 60 to get Hz  so 16k Multiply by 60 will be 96khz_


----------



## stevehuckss396

dsage said:


> Steve:
> 
> Looking back a bit I see I missed your one liner asking about the IGBT transistor.
> I goofed up my drawing part number (sort of)
> The correct part number is an IRGB14C40LPBF not IRGS....
> Same part but the IRGB is a TO220 tabbed variant capable of being screwed down.
> I guess too many numbers and letters to get straight in my head.
> 
> Having said that for a low power application the tab(less) device would probably run cool enough to survive right on the board.
> 
> I updated the drawing in the previous post.
> 
> Thanks
> 
> Sage





Roger That!

I am going to build the version 2.1 circuit with the device I have on hand. I am hoping to get the board done Sunday and do some testing. Should have some news Sunday night if I dont have to work.


----------



## dsage

>>> _their is 3600 seconds in one hour so take your RPM multiply it by 60 to get Hz so 16k Multiply by 60 will be 96khz_ 

Not sure how HOURS started figuring into it. We were talking about revolutions PER MINUTE and sparks per MINUTE and Hz - sparks per second.

If you have 16,000 sparks in a minute you have 1/60th that many in a second (there are 60 seconds in a minute)

Do you actually think the engine puts out 96,000 sparks per second ?? Think about it. (the definition of Hz is per second)

16,000 sparks per minute / 60 seconds in one mnute = 16,000 / 60 = 267 sparks per second.

Figure it backwards.

267 sparks per second x 60 seconds per minute = 267 x 60 = 16,000 sparks in one minute.


Let's look at it yet another way
The engine is rotating at 4000 RPM that's 67 revolutions per second
By your calculation - where's the engine going to get rid of 96000 sparks in 67 revolutions.

Sage


----------



## dsage

Ok Steve:

Let me know if something doesn't look right. I'll be glad to help you work through it.

Sage


----------



## Mosey

stevehuckss396 said:


> Roger That!
> 
> I am going to build the version 2.1 circuit with the device I have on hand. I am hoping to get the board done Sunday and do some testing. Should have some news Sunday night if I dont have to work.



Of course you are building an extra for me aren't you?

Hang int here, Buddy, you're doing great!

Mosey
(Got my TIM-6 today)


----------



## cfellows

Really interesting thread.  Steve, have you calculated how much the parts, excluding circuit board, will cost for this?

Also, would be interested in knowing the maximum current this circuit can supply to the coil.

Finally, would this circuit work with points or a micro switch instead of a hall effect device?

Thx...
Chuck


----------



## stevehuckss396

Hello Chuck!

The components cost me $11.81 excluding the board. $14.31 including the board. Because the resistors come in a 5 pack, if you make 5 of them it would be $7.04 each or $8.54 with the board. The board is a blank 4 X 6 inch that I had to cut on the mill with an engraving bit.

The output transistor is rated 15 amps with the proper heat sink.

I believe it would work with a switch from the output to the negitive. If we can get Dsage or CHP to verify that I will redraw the circuit with the switch in it for future reference.


----------



## canadianhorsepower

*



			I believe it would work with a switch from the output to the negitive. If we can get Dsage or CHP to verify that I will redraw the circuit with the switch in it for future reference
		
Click to expand...

* 
Hi Steve, 
sure it will work but I'm a little bit confuse  why add points condensor and wires, or switch and wires when all you need is a magnet
now one question about your project why are your magnet spread 135 apart???????????


----------



## canadianhorsepower

can someon tell me how to remove to yellow question marks that keep showing on


----------



## stevehuckss396

canadianhorsepower said:


> Hi Steve,
> sure it will work but I'm a little bit confuse  why add points condensor and wires, or switch and wires when all you need is a magnet
> now one question about your project why are your magnet spread 135 apart???????????



Some folks might already have a model with points in it and want to go to an electronic ignition. It would be an option for repairing or replacing an existing ignition.

The magnets are 135 degrees apart because the combustion cycle of the engine is 270 degrees apart.

Pop - 270 - pop - 450 - pop - 270 - pop


----------



## stevehuckss396

canadianhorsepower said:


> can someon tell me how to remove to yellow question marks that keep showing on




Can't help you there.


----------



## dsage

Chuck:

Yes. A set of points or a switch connected to ground from the point labeled "OUT" now from the hall sensor would work just fine. No condenser (capacitor) or other parts required.

Perhaps Steve can draw that option for us.

Sage


----------



## stevehuckss396

dsage said:


> Chuck:
> 
> 
> Perhaps Steve can draw that option for us.
> 
> Sage




Perhaps!


----------



## stevehuckss396

cfellows said:


> Really interesting thread.  Steve, have you calculated how much the parts, excluding circuit board, will cost for this?
> 
> Also, would be interested in knowing the maximum current this circuit can supply to the coil.
> 
> Finally, would this circuit work with points or a micro switch instead of a hall effect device?
> 
> Thx...
> Chuck




Chuck!

I did not consider the terminal blocks in that post. The only reason I put terminals on the board is so I will be able to change it out easily if it fails at one of the 2 shows I display at. If it's going to fail, that's where it will happen.


----------



## canadianhorsepower

dsage said:


> Chuck:
> 
> Yes. A set of points or a switch connected to ground from the point labeled "OUT" now from the hall sensor would work just fine. *No condenser (capacitor) or other parts required.*
> 
> Perhaps Steve can draw that option for us.
> 
> Sage


 
Hi I don't know if it's because it makes you feel better or if your just enjoying
contradicting what I'm saying, but the end result is unfair to post readers.

I think that your bright enought to know that 6 inch of twisted pairs of wire will make noise in a circuit, a mechanical switch is even worst. I think that you also know that debouncing circuit ( to eliminate noise from a switch)is very popular, that using a matching capacitor is a common practice, then why not playing it safe with your buddy and tell them the truth.

I know and You know that a small capacitor across the switch or the point
wont affect the circuit. But you also know that if one was needed and was not install then problem will happen.

Steve, a small cap .01uf is like 4 cents put one in it's like inssurance to a good working circuit


----------



## Mosey

canadianhorsepower said:


> Hi I don't know if it's because it makes you feel better or if your just enjoying
> contradicting what I'm saying, but the end result is unfair to post readers.
> 
> I think that your bright enought to know that 6 inch of twisted pairs of wire will make noise in a circuit, a mechanical switch is even worst. I think that you also know that debouncing circuit ( to eliminate noise from a switch)is very popular, that using a matching capacitor is a common practice, then why not playing it safe with your buddy and tell them the truth.
> 
> I know and You know that a small capacitor across the switch or the point
> wont affect the circuit. But you also know that if one was needed and was not install then problem will happen.
> 
> Steve, a small cap .01uf is like 4 cents put one in it's like inssurance to a good working circuit


I for one, enjoy the polite and respectful tone of this forum. Please eliminate the harsh and possibly antagonistic aspects of your posts, so the wisdom and knowledge can stand on their own. Thanks,
Mosey


----------



## canadianhorsepower

> I for one, enjoy the polite and respectful tone of this forum. Please eliminate the harsh and possibly antagonistic aspects of your posts, so the wisdom and knowledge can stand on their own. Thanks,
> Mosey


 
Mosey, sorry to desapoint you I dont see any thing beeing impolite or disrespectful. I'm only describing what's going on and thats it.
I think that if someone is asking for help it is mostly because of a lack of knowledge and should not be side track for any reason.

cheers


----------



## Les_S

Hi Steve,
I hope your experimentation is going well. I agree with Luc and Sage that spinning some magnets would be an ideal test whether you use a small electric motor or spin a disc with a variable speed drill or whatever might be handy for you. I would try to keep the magnet spacing diameter the same as it will be on your engine and use the same magnets you intend to use.

Sorry this post is so long winded but maybe it might be beneficial to some folks. If you choose to ignore this post I certainly understand.

I have built on your schematic a little and offer a couple of suggestions for experimentation. Your circuit is coming along nicely and I think it will work as is so take my ideas for just what they are. A possible way to improve your circuit.

Both Q1 and Q2 in your circuit will be used as switches. Therefore, there is no need to bias either transistor as you would if you were building an amplifier. That means that the only purpose for R1 and R4 are to keep the transistor base from floating when the transistor is off. If neither R1 or R4 were present then there is a chance the transistor could be turned on from transient current surges with enough amplitude to forward bias the transistor. Rule of thumb is R1 and R4 should be 10x R2 and R3 respectively which I have shown in the drawing. The actual value for R1 and R4 doesn't really matter so much as long as it keeps the base of the transistor pinned close to the supply rail when the transistor is off (12V for Q3 and ground for Q4). The problem with making R1 and R4 too small is that the resistors will rob part of the current that you want to drive the transistor base to drive your coil. For instance, as drawn originally, R4 is 1000 ohms. Q2 is a darlington transistor so the turn on voltage is going to be approximately 1.5V. At 1000 ohms the current through R4 will be 1.5 mA. Max current through R3 will be (12V - approx .7V for 2N3906 emmiter diode - 1.5V for BU941 darlington emitter pair) = 9.8V / 470 ohms = 20.8 mA. Subtract the 1.5 mA in parallel with Q2's base and you have about 19.4 mA. Multiply that by 300, which is approximately the gain of Q2 and you have a maximum of about 5.82A to drive your coil. Using a value of 4.7k for R4 would result in a current through R4 of approx 0.3 mA which would result in approx 20.5 mA hitting the base of Q2 or 6.15A through your coil. Not a huge difference (+5.4% increase) but illustrates the point.

I am also suggesting the use of D1 (1N914 or 1N4148) between the output of the SS441A and ground as shown. I couldn't find any data for the output transistor in the SS441A data sheet but your BU941 output transistor has an internal protection diode that will provide a current path when the ignition coil collapses and creates a spark. That current path will result in a short duration voltage surge (on the order of a few hundred volts) of opposite polarity that could quite possibly wipe out the SS441A output transistor. The diode will prevent that.

I am also suggesting the use of a filtering capacitor (C1) placed as close as possible to the power terminals of the SS441A. The SS441A has an internal voltage regulator and the capacitor will help remove any surges from the power supply. My preference would be a tantalum capacitor but an electrolytic (around 100uf) and a ceramic disk (around .1 uf) in parallel would probably work equally as well.

Luc and Sage both have correctly said that inverting the signal so the magnetic pulse discharges instead of charges the coil may work well for your motor considering you will be using a "wasted spark" setup for your motor. Your circuit lends itself well to inversion because your output transistor is a darlington and will require 1.5 volts or so to turn it on. The output transistor of your SS441A will saturate @ about .4 volts which will definitely turn the BU941 off. The benefit is that your coil will have more than enough time to charge up. The downside, as Luc and Sage have both pointed out is:

1) reduced battery life
2) your coil may run hot
3) your output transistor will definitely run hotter

Best regards,
Les


----------



## stevehuckss396

Thanks Les, Dsage, CHP, but it looks as if i'm moving on to plan B. The coil would not fire. I could see the voltage changing at the primary side but no spark. I am going to figure out another way. Even if the circuit didn't work for me, at least there is a good circuit that came out of it. I am sure it will help someone here. I'm sorry all your hard work added up to nothing but i'm sure if it were a standard coil the circuit would have worked just fine.


----------



## canadianhorsepower

stevehuckss396 said:


> Thanks Les, Dsage, CHP, but it looks as if i'm moving on to plan B. The coil would not fire. I could see the voltage changing at the primary side but no spark. I am going to figure out another way. Even if the circuit didn't work for me, at least there is a good circuit that came out of it. I am sure it will help someone here. I'm sorry all your hard work added up to nothing but i'm sure if it were a standard coil the circuit would have worked just fine.


 
Hey Steve,   
I'll buy them I have a serious problem when a piece of wire
put together by a human beeing won't respond:wall: if (when) I'll suceed
if you wont them back no problemo  you'll get them back like you mentioned before they belong
to that comp/engine project

What's your plan B???

I don't know how much electronic you do, but if you send me a pm I will email you this book

good luck, the_ "Paint artist"Rof}Rof}Rof}_


----------



## cfellows

Steve, have you tried the coil with a standard auto condenser and points or some other kind of make / break?  I know a regular auto ignition system with points and a coil won't work without the condenser.  

Chuck


----------



## cfellows

Here are some schematics to Ignition Circuits that might be useful...

http://www.5bears.com/tim4.htm

Chuck


----------



## canadianhorsepower

I think that with all what Steve heard about with ignition :rant::wall:???:shrug:stickpokescratch.gif:-[th_rulze*club*:redface2:*discussion*
The next project will be a DIESEL engine Rof}Rof}Rof}Rof}Rof}


----------



## stevehuckss396

cfellows said:


> Steve, have you tried the coil with a standard auto condenser and points or some other kind of make / break?  I know a regular auto ignition system with points and a coil won't work without the condenser.
> 
> Chuck




Hello Chuck!

It will fire a standard coil. It's the duel coil that doesn't want to work.


----------



## stevehuckss396

canadianhorsepower said:


> Hey Steve,
> 
> What's your plan B???



I don't have one yet. Need to take a step back and figure out what I want to do.


----------



## Lakc

stevehuckss396 said:


> I don't have one yet. Need to take a step back and figure out what I want to do.


I have been working on plan B all along.  Taking a break now, as I am tired of debugging a/d and interrupt code. Good news is I managed to create very scary voltages across large capacitors. Bad news is I smoked the two Pic16F690's I was using for development. :rant:
But the spark that did it was glorious


----------



## dsage

Les:

All good suggestions. I'm not sure where the original circuits were coming from. My efforts were simply to eliminate some of the more obvious issues with the circuit(s) as presented. 
I agree that all of your suggestings would improve / protect the circuit beyond the original basic design presented. Having said that, the circuit should (and apparently does) work as it has evolved. Adding any of your suggestions would certainly make it more robust.
If I had the luxury of starting over I'd design the IGBT circuit I presented way back in post 17. I guess it's probably not perfect either but we are always trying to balance complexity with benefits / cost.

Re: the other circuit:
Although having the coil energized all of the time would give you a spark right away (when the transistor is triggered off) it might lead to more problems than benefits. The transistor would be dissipating 6A x 1.5 volts = 9 watts almost contunuously. Also, most guys are using batteries of about 7Ah (at a 20hour rate). With 6A continuous the battery might not last long. Of course this is how car ignitions operate but then there is an alternator as backup.

I'm sure Steve is frustrated at the moment. He says it fires a standard coil so I'll have to assume the dual output coil has problems. I'll think about it a bit and suggest a test.

Canadianhorsepower:

The input impedane of the circuit with the switch actvating the transistor directly is more or less about 680 ohms. It is unlikely there would be any "noise" on the switch leads large enough to bias the transistor on (requiring at least 10ma of current). But, like you said, small capacitors are cheap and a small .01uf wouldn't hurt.
(Now don't anyone criticize that statement because at some point the capacitor will slow down the transistor switching off time, but we won't go there).
There are lots of things that "could" be added to any circuit and most times you need to test these things on the bench, see where you have problems, and fix those problems.
Unfortunate that you chose to accuse me of lying to everyone that the capacitor IS need and I was somehow CHOOSING to not tell them about it.

Sage


----------



## canadianhorsepower

> Canadianhorsepower:
> 
> The input impedane of the circuit with the switch actvating the transistor directly is more or less about 680 ohms. It is unlikely there would be any "noise" on the switch leads large enough to bias the transistor on (requiring at least 10ma of current). But, like you said, small capacitors are cheap and a small .01uf wouldn't hurt.
> (Now don't anyone criticize that statement because at some point the capacitor will slow down the transistor switching off time, but we won't go there).
> There are lots of things that "could" be added to any circuit and most times you need to test these things on the bench, see where you have problems, and fix those problems.
> Unfortunate that you chose to accuse me of lying to everyone that the capacitor IS need and I was somehow CHOOSING to not tell them about it.
> 
> Sage


 

:bow::bow::bow:Rof}Rof}Rof}:bow::bow::bow:
does that make youre ego better


----------



## dsage

Steve:

Sorry to bug you.
I'd just like to close the loop on a few things suggested earlier.

Did you (or could you) try the dual output coil by:

Use a spark plug in free air (not in the engine)
Connect a clip lead from one HV lead to the tower of the plug
Take a second clip lead from the other HV lead to the threads of the plug. Use no grounds on the plug.

I'm sure you probably tried this but I didn't see the results of this test.

I think you responded that the circuit will fire your old school coil - right? If not I /we can suggest a few circuit troubleshooting ideas.

One right off the top:
Arrange a voltmeter across the primary of the dual output coil (+/- leads), preferrably with clip leads so your hands are free. 
With the magnet NOT activating the hall sensor you should measure zero volts.
Activate the hall sensor with a magnet JUST LONG ENOUGH to take a stable measurement on the meter.
What do you see?

I think you said the resistance of the coil primary was 0.8 ohms?
Did you take into consideration the resistance of your meter leads? Short your leads together and take that measurement and subtract it from your coil measurement. Why? because the meter leads might measure as much as 0.2 ohms themselves.

What do you get?

It's difficult to tell what "normal" would be for any coil. You might compare it to your "good" coil. I have an old-school coil here and it measures 0.2 ohms. (Not sure where I'm going with this one).

Sage


----------



## stevehuckss396

Lakc said:


> I have been working on plan B all along.  Taking a break now, as I am tired of debugging a/d and interrupt code. Good news is I managed to create very scary voltages across large capacitors. Bad news is I smoked the two Pic16F690's I was using for development. :rant:
> But the spark that did it was glorious



Did you want me to bring this coil to you? I can drop it off anytime this week. I have a brand new one still in the box.


----------



## stevehuckss396

dsage said:


> Steve:
> 
> Did you (or could you) try the dual output coil by:
> 
> Use a spark plug in free air (not in the engine)
> Connect a clip lead from one HV lead to the tower of the plug
> Take a second clip lead from the other HV lead to the threads of the plug. Use no grounds on the plug.




Yep, did that


----------



## Lakc

stevehuckss396 said:


> Did you want me to bring this coil to you? I can drop it off anytime this week. I have a brand new one still in the box.


Not necessary at the moment, but if you have an itch to see if that coil will spark my mk1 ignition seems to make sparks outside of the combustion chamber all day long. Your welcome anytime.


----------



## Les_S

Steve,
I hope you get the ignition going. I know you are close. I wish I had your coil to play with because that is the greatest unknown at this time for me anyways. 

Sage, I think you are nuts on with all of your comments. I like your idea of an IGBT but it looks like to me that Steve made a good choice for an output transistor. I just can't tell what might be going on.

Luc, You are a very smart man and I appreciate your input. I haven't thought about a 741 op amp forever  I'm sure there is a thing or two I could learn from you.

Gentlemen, I have learned much from everybody involved. I think it best that I bow out now and wish Steve the best. You are close my friend, make some sparks


----------



## stevehuckss396

dsage said:


> Steve:
> 
> Arrange a voltmeter across the primary of the dual output coil (+/- leads), preferrably with clip leads so your hands are free.
> With the magnet NOT activating the hall sensor you should measure zero volts.
> Activate the hall sensor with a magnet JUST LONG ENOUGH to take a stable measurement on the meter.
> What do you see?
> 
> I think you said the resistance of the coil primary was 0.8 ohms?
> Did you take into consideration the resistance of your meter leads? Short your leads together and take that measurement and subtract it from your coil measurement. Why? because the meter leads might measure as much as 0.2 ohms themselves.




I don't remember. I was getting voltage one way and not the other but I cant remember if the voltage would rise on magnet presence or fall. I also checked the hall sensor output. It measured 12 volt until magnet presence and then fell to almost zero.

I just double checked. The leads shorted was 0.2 ohms and across the coil was 1.0.


----------



## dsage

Lakc:

 LOL

I've been there done that. I designed a really nice CDI ignition module and after getting it to produce (as you say) "glorius sparks" I also blew it up quite gloriously. Changing the PS switching transistors in my (crammed) board layout was a real pain.

It was at that point I figured out that I would quit trying to impress myself with big long sparks and that big long sparks are a BAD thing . 
I added a "protection gap" on the HV lead to ground about maybe three times the gap of a typical plug to limit the spark voltage in case the plug(s) go bad or the HV lead falls off. (You could also damage the coil with internal carbon traces between windings)
(not that you don't already know any of that)

In this case bigger (longer) is not better. 

I now listen for nasty sounding and really hot looking sparks at a standard spark plug gap. Especially impressive at high frequencies.

I'd really be interested in your design. Mine did not include a uProc.
Are you using the uproc in the power supply or the input side?

You're a brave man designing anything with HV or high frequencies which includes a uProc. It can be a real nighmare chasing down noise issues. If you're having success my hat is off to you. Good board layout is a science and a must (as you've obviously figure out ).

Although working really well, I set mine aside on the bench for further development. It was a bit large for a model engine use. But much smaller than a typical MSD unit. I need to scale the PS section down a quite a bit. More power than necessary - takes up too much space.

Having said all of that, if Steve's coil is FooBar even a CDI is not going to help. Or are you figuring something else about the coil??

Sage


----------



## stevehuckss396

dsage said:


> Having said all of that, if Steve's coil is FooBar even a CDI is not going to help.
> Sage




I have another new one. It is brand new in the box. If Lakc can get it sparking, i can just terminate the ends and put the boots on. If Lakc blows it up I could care less. There's always plan C


----------



## dsage

What !!! - you have another coil 
Why don't you try the new coil on your circuit. Maybe you just got a dud (understandable from Ebay me thinks)
I can't imagine how the circuit could be damaging the coils since the worst you can do is put the coil right across 12V and that's what's it's designed for. (Hmm - it is a 12v coil isn't it?)
It would have damaged the old-school coil.

If you have no HV boots, temporarily use short clip leads on the HV leads to the plug (be careful, don't leave them open circuit).

I think you're on the right track using this type of coil since you've done a lot of work to arrange for it and it looks great.

I wish I had more suggestions.


Sage


----------



## RamTurret602

Hello Everyone,

           I am new here. I assume that you folks are talking about ignition for model engines? If so anyone using CDI?


----------



## Lakc

dsage said:


> Lakc:
> 
> LOL
> 
> I've been there done that. I designed a really nice CDI ignition module and after getting it to produce (as you say) "glorius sparks" I also blew it up quite gloriously. Changing the PS switching transistors in my (crammed) board layout was a real pain.



Still on the proto board right now, only 2x the noise issues like that.



> I'd really be interested in your design. Mine did not include a uProc.
> Are you using the uproc in the power supply or the input side?



This version runs the whole shebang, generates the pwm for the flyback coil, measures the high voltage for cutoff and hold, watches the trigger and fires the scr. The previous version used another controller chip to handle charging the capacitors.



> You're a brave man designing anything with HV or high frequencies which includes a uProc. It can be a real nighmare chasing down noise issues. If you're having success my hat is off to you. Good board layout is a science and a must (as you've obviously figure out ).



 Ignorance is often equated for bravery.  I came into electronics backwards, as an auto tech and then a Ham. I know enough to get myself into trouble, and still have a hard time thinking of 30khz as high frequency. 



> Having said all of that, if Steve's coil is FooBar even a CDI is not going to help. Or are you figuring something else about the coil??
> 
> Sage



Steve has two new coils, I dont think they both are bad. His trouble with the resistance readings make me wonder if they have an internal clamping diode. Although I have never seen that done, it does not seem out of the realm of possibility.


----------



## canadianhorsepower

Les_s: thanks for your comment

Steve: I have two more sugestion for you
#1 would be to simply replace your coil with a led and a 470 ohm resistor in series and slowly turn  your motor
by hand. this would tell you how long your charge time is. the led should be off only when the magnet is in front
of your hall sensor .
#2 this is the method _*"if in doubt use C4"Rof}*_ use a variac and increase the input voltage and use a 120 volt house swithc
to control your pulse. In crease the voltage more and more and look what the outcome is. I know for a fack that some miniature coil
need 200 volt on the input to work could be you case

And if plan C doesn't work.... so what their is 23 other letter in the alphabet  Thm:


----------



## Lakc

RamTurret602 said:


> Hello Everyone,
> 
> I am new here. I assume that you folks are talking about ignition for model engines? If so anyone using CDI?



Welcome aboard!
This thread has been mostly about one particular engine and application. I dont recall a lot of CDI discussion around here. I do have one under development.


----------



## Lakc

canadianhorsepower said:


> Les_s: thanks for your comment
> #2 this is the method _*"if in doubt use C4"Rof}*_ use a variac and increase the input
> And if plan C doesn't work.... so what their is 23 other letter in the alphabet  Thm:



Plan D is "*if in doubt use a 3-500z*"


----------



## dsage

It sounds like all of you are thinking that maybe the coil was originally designed for CDI activation. Good thinking. Canadianhorsepower may have a good idea there in so far as applying an AC waveform to the primary - even if it's from say a 12VAC transformer - if a variac is not available. I think what he's suggesting is that if you had a scope (or a meter depending on the voltage produced) on the output you could measure the output and determine the turns ratio. Treating the coil more as a transformer not as a high voltage generator just for investigation purposes. Not a bad approach since the coil does seem to be odd.
I would assume a coil designed for a high voltage input would have a low turns ratio. Of course I'd only be guessing what a typical coil turns ratio would be - maybe 100? You may have to do the same thing with the old-school coil and compare them.

Are there any identifying numbers on the coils that can be traced to a particular manufacturer. Which might lead to what they were used on and further what they were firing it with?

Probably grasping at straws with all of this but certainly it seems the coil is somehow different than a typical one.

I guess success or failure using the CDI will tell it all.


BTW - what's a 3-500Z ?

Sage


----------



## Lakc




----------



## Mosey

Duh,
Here's an idea called "I don't know nutthin".

Dump that coil and try one you know to be good. I'll let you know where to send the check later.

Mosey


----------



## dsage

Lakc:

Transmitter tube - right? 
I guess if you had the plate voltage for that baby you wouldn't need the coil. Just big relay. I'm not sure how long the sparkplug contacts would last though.

I think you said you had your CDI working (sort of) on the bench with a regular coil - am I right?
Maybe you should just hook up Steve's coil in place of yours and see what you get. The CDI circuit need not be finished if it proves the point and gives some sort of spark. Especially if Steve gets diddly.


Mosey:
Apparently Steve has a couple of more coils he could try. It's possible the one he's been trying is a dud but considering that they are all from the same batch they are probably all in the same boat (good or bad). It's likely we're missing something about driving it properly. 
He has tried a conventional coil and apparently it works. 

Sage


----------



## canadianhorsepower

> The magnets are 135 degrees apart because the combustion cycle of the engine is 270 degrees apart.
> 
> Pop - 270 - pop - 450 - pop - 270 - pop


 
Steve, I'm totaly lost where does that 450 comes from. I must assume that your crank is like a V-TWIN motorcycle

BTW are you trigging that hall sensor with a south pole and with ground are you using to check your spark your primaty
or your case ground


----------



## Lakc

dsage said:


> Lakc:
> 
> Transmitter tube - right?
> I guess if you had the plate voltage for that baby you wouldn't need the coil. Just big relay. I'm not sure how long the sparkplug contacts would last though.


Yes, good for a kilowatt or so. Make the inductance of the piston mistune a rf circuit and it oughtta spark on its own right. 


> I think you said you had your CDI working (sort of) on the bench with a regular coil - am I right?
> Maybe you should just hook up Steve's coil in place of yours and see what you get. The CDI circuit need not be finished if it proves the point and gives some sort of spark. Especially if Steve gets diddly.


Indeed, if Steve wants to make the trip, the offer is open. 
If all goes well, version 2 of my CDI is only a few hours from working itself. Of course, two hours of "going well" can sometimes take weeks...


----------



## modelman1838

Hi 
Last week I decided to give my old Wyvern IC engine which has been gathering dust a makeover and give it a run. The original coil and buzz circuit that I had used was now used on another engine so I had to look elsewhere. Not wishing to spend much money since I would only run it once, I purchased a " Masterclass" electric gas lighter for £7-69p from ebay. I took it apart and removed the switch part and connected the microswitch which was used for the contact points in its place, attached the spark wire which was`nt even HT to the plug terminal gave the engine a flip and off she went a treat. Not a bad complete ignition circuit for 
£7-69p I think.
Hugh


----------



## Mosey

dsage said:


> Lakc:
> 
> Transmitter tube - right?
> I guess if you had the plate voltage for that baby you wouldn't need the coil. Just big relay. I'm not sure how long the sparkplug contacts would last though.
> 
> I think you said you had your CDI working (sort of) on the bench with a regular coil - am I right?
> Maybe you should just hook up Steve's coil in place of yours and see what you get. The CDI circuit need not be finished if it proves the point and gives some sort of spark. Especially if Steve gets diddly.
> 
> 
> Mosey:
> Apparently Steve has a couple of more coils he could try. It's possible the one he's been trying is a dud but considering that they are all from the same batch they are probably all in the same boat (good or bad). It's likely we're missing something about driving it properly.
> He has tried a conventional coil and apparently it works.
> 
> Sage


I don't mean to butt in with smartypants comments, especially in an area where I know next to nothing, but what I do mean is to put a brake on the experimentation by using a conventional device. It's about the engine, and getting it to run. Unless Steve is happy putting in tons of time.
Mosey


----------



## dsage

Mosey:

No problem here. I didn't interpret it as a "smatypants" remark.  

 If you mean he should bite the bullet and buy a new coil, as I understand it these coils are hard to find and the design of the engine (so far) requires this type of coil. I was wondering if maybe he could get someone who stocks the coils interested in what's he's doing enough to borrow a known good coil to try.
It's pretty simple like it is. I hope he can get it working.


Not sure if you're coming into this late but the engine is a little different arrangement than most. Ignore below if you know what's going on.

For the benefit of others:

 Correct me if I'm wrong Steve:
The engine has no distributor (shaft or otherwise) - only a container that looks like one. Inside there is the circuit to drive the coil. The coil is a bit different in that it can fire both cylinders at once. The coil drive circuit is fired by a hall sensor and magnets. In order to use a conventional coil he'd have to add a distributor and drive shaft from the camshaft  or use two coils and two circuits. 

Sage


----------



## dsage

Modelman1838:

Brilliant idea. I think I have one of those on my barbeque. It has batteries right? I also have one of the other push buttton "snappy types".
Do you know how that electric one works?

I have seen engines using a mechanical piezo ignitor with a  cam to snap the button like you would by hand. But not using the electric kind. Cool.

I'm wondering if it would have trouble with higher compression. Any idea what the compression is on your engine. I'm not familiar with that engine.

I'll have to remember that trick. Ignitions are always a pain.

Thanks

Sage


----------



## stevehuckss396

Lakc said:


> Steve has two new coils, I dont think they both are bad.




One of them is now. I ripped the HV wires out of it to try another experiment. I do have another one brand new in the box.


----------



## stevehuckss396

dsage said:


> What !!! - you have another coil
> Why don't you try the new coil on your circuit.



I might have already smoked the first coil, I didn't want to try the same thing and smoke the other one.


----------



## stevehuckss396

canadianhorsepower said:


> Les_s: thanks for your comment
> 
> Steve: I have two more sugestion for you
> #1 would be to simply replace your coil with a led and a 470 ohm resistor in series and slowly turn  your motor
> by hand. this would tell you how long your charge time is. the led should be off only when the magnet is in front
> of your hall sensor .
> #2 this is the method _*"if in doubt use C4"Rof}*_ use a variac and increase the input voltage and use a 120 volt house swithc
> to control your pulse. In crease the voltage more and more and look what the outcome is. I know for a fack that some miniature coil
> need 200 volt on the input to work could be you case
> 
> And if plan C doesn't work.... so what their is 23 other letter in the alphabet  Thm:





#1 - Yeah I can try that. I might have some time this weekend to do some more testing.

#2 - Yeah I cant do that. I don't have the means or equipment to do that.


----------



## Lakc

stevehuckss396 said:


> I might have already smoked the first coil, I didn't want to try the same thing and smoke the other one.


Istr all the Dodge Neon's used a pair of single coils with dual output. At the expense of remaking a bracket, you wont be sol if you need to go to another design.


----------



## Lakc

stevehuckss396 said:


> #1 - Yeah I can try that. I might have some time this weekend to do some more testing.
> 
> #2 - Yeah I cant do that. I don't have the means or equipment to do that.


I have my whole house torn up looking for my variac right now. I had intended on making an induction heater as my next project when all this ignition stuff started to come up. Now the place is an unbelievable mess.


----------



## stevehuckss396

canadianhorsepower said:


> Steve, I'm totaly lost where does that 450 comes from. I must assume that your crank is like a V-TWIN motorcycle
> 
> BTW are you trigging that hall sensor with a south pole and with ground are you using to check your spark your primaty
> or your case ground




It's a 90 degree v so it pops coasts 270 and pops again. Then the motor has to coast 450 degrees back to TDC #1.

270 + 450 = 720 degrees. two 360 degree rotations for a 4 stroker.

I trigger the hall sensor with what ever side makes it turn on and off. It isn't marked so I have no idea what pole that is.

I check the spark by putting one HV lead to the sparkplug cap and the other HV lead to the threads of the sparkplug.


----------



## stevehuckss396

Lakc said:


> Yes, good for a kilowatt or so. Make the inductance of the piston mistune a rf circuit and it oughtta spark on its own right.
> 
> Indeed, if Steve wants to make the trip, the offer is open.
> If all goes well, version 2 of my CDI is only a few hours from working itself. Of course, two hours of "going well" can sometimes take weeks...




Thanks Jeff for the offer but I will wait until you feel you are ready. When you think it is the best it can be drop me a note and i'll bring the coil over and you can work your electronic magic on it.


----------



## stevehuckss396

Mosey said:


> I don't mean to butt in with smartypants comments, especially in an area where I know next to nothing, but what I do mean is to put a brake on the experimentation by using a conventional device. It's about the engine, and getting it to run. Unless Steve is happy putting in tons of time.
> Mosey




Hey smartypants!!  How you doing. 

There are a couple things that keep me from going conventional. To go the distributor route I would need to make another camshaft because the current cam does not have a long enough tail to attach the rotor. I had to keep it short so it would clear the circuit board. I could make the parts and get it going. I guess I'm not ready to give up on this thing yet. If we get it running with the current setup it will be like no other and look real nice. I have 2 that run on the distributor. I guess I want something different. Who knows how many people this might help in the future. Everything you have ever seen on this site was an experiment at one time.

We'll get er Mosey. And don't worry about posting in a thread where you know next to nothing. I have been doing it all along!!


----------



## canadianhorsepower

> It's a 90 degree v so it pops coasts 270 and pops again. Then the motor has to coast 450 degrees back to TDC #1.
> 
> 270 + 450 = 720 degrees. two 360 degree rotations for a 4 stroker.
> 
> I trigger the hall sensor with what ever side makes it turn on and off. It isn't marked so I have no idea what pole that is.
> 
> I check the spark by putting one HV lead to the sparkplug cap and the other HV lead to the threads of the sparkplug.


 
Thank for the explanation, now i get it
as for your ign sys your hall is a unipolar and it will only trigger with south pole
as I mentione before thats not realy a coil but a step up transformer to check your spark you have to go
with (of course) the HT output but the ground must be the laminated steel of your coil itself


----------



## canadianhorsepower

> #1 - Yeah I can try that. I might have some time this weekend to do some more testing.
> 
> #2 - Yeah I cant do that. I don't have the means or equipment to do that.


 
for #2 you can put 4     60 watt bulb in serie acting as a voltage devider you would have 30 60 90 120 volt ac output


----------



## Les_S

Hi Steve,

I said I was bowing out but couldn't resist. Do you happen to have a part number for your coil or know what the original application was? (forgive me if it was posted earlier). I've been reading up on some of the wasted spark systems and it appears that most coils don't like to have either HT lead grounded which sounds like the method you were using to test with one spark plug. Also, it appears that some of the control modules that run these coils actually use a PCM signal which would make the coil act more like a transformer and produce multiple sparks per hit instead of a single spark each time one of the two plugs is supposed to fire. If I can get my hands on a coil the same or very similar to yours I'll pick one up and see if I can have my way with it.

Best Regards,
Les


----------



## canadianhorsepower

Gentelmens we have a problem:hDe:

I waited a few days before posting this, I did duplicate all the versions that was offered 
to Steve ALL of them are working with a regular coil, none with a waiste typeth_confused0052
my next step being a GM Grand Master Tech I have some small advantage.
I will have a new crank sensor ign module and coils to do all the testing I want to.
Dont try a variac I have a variable AC power supply and i was tripping 10 amp reset
cheers


----------



## Lakc

canadianhorsepower said:


> Gentelmens we have a problem:hDe:
> 
> I waited a few days before posting this, I did duplicate all the versions that was offered
> to Steve ALL of them are working with a regular coil, none with a waiste typeth_confused0052
> my next step being a GM Grand Master Tech I have some small advantage.
> I will have a new crank sensor ign module and coils to do all the testing I want to.
> Dont try a variac I have a variable AC power supply and i was tripping 10 amp reset
> cheers



I would not expect anything exotic for a reason, like the secondary center tapped to ground. Did you simulate the spark passing through a ground in common with the primary?
In automotive use, these coils are driven rather hard. So hard, that they crack and fail if the driver circuit is not functioning correctly. These are not like the old oil filled coils that can tolerate full voltage constantly. 
While I am unhappy with the spark from my MKI version of my CDI, it does spark.


----------



## stevehuckss396

Les_S said:


> Hi Steve,
> 
> I said I was bowing out but couldn't resist. Do you happen to have a part number for your coil or know what the original application was? (forgive me if it was posted earlier). I've been reading up on some of the wasted spark systems and it appears that most coils don't like to have either HT lead grounded which sounds like the method you were using to test with one spark plug. Also, it appears that some of the control modules that run these coils actually use a PCM signal which would make the coil act more like a transformer and produce multiple sparks per hit instead of a single spark each time one of the two plugs is supposed to fire. If I can get my hands on a coil the same or very similar to yours I'll pick one up and see if I can have my way with it.
> 
> Best Regards,
> Les



I don't have a part number or even a manufacturer. It was for a 90's snomobile or seadoo. 

I did not ground either HV lead. Just simply connected one to the top and one to the threads of the sparkplug while it layed on a rag on the bench.


----------



## canadianhorsepower

beeing a Grand Master Certification I can assure you that these areThis posting whent with more testing
than no one can think of. I should have a new module tomorrow with 3 other coils to check what is realy comming out
of those wires getting this coil to work. 
it's going to need aaaalllooottt of power with my ac ps I was blowing 20 amp fuses


----------



## Lakc

Pardon the messy bench.





[ame]http://youtu.be/M3_7SiNVw08[/ame]

Yes thats 537 volts showing on the old Fluke. If it aint somehow dangerous it aint fun. 
Not finished yet, few things still left to work out, but the first few pops always make you feel better.


----------



## Les_S

Thanks Steve,
I misunderstood how you had your coil hooked up.

Luc, it will be interesting to see what you come up with for the GM coils.

Jeff, that is some serious looking breadboarding there! be careful


----------



## dsage

Lakc:

Messy ??

Looks like the place blew up 

Looks like you're on your way.

Can you activate the circuit with a pulse generator (555) or I guess since you have the uP you could have it activate itself. 

Sometimes (most often) things go bad fast when you generate a lot of sparks in a hurry. RFI EMI power supply failure....

It's really satisfying to hear (and see) the circuit generate sparks at engine frequencies. (he says biting his tongue )


Sage


----------



## Lakc

dsage said:


> Lakc:
> 
> Messy ??
> 
> Looks like the place blew up
> 
> Looks like you're on your way.
> 
> Can you activate the circuit with a pulse generator (555) or I guess since you have the uP you could have it activate itself.
> 
> Sometimes (most often) things go bad fast when you generate a lot of sparks in a hurry. RFI EMI power supply failure....
> 
> It's really satisfying to hear (and see) the circuit generate sparks at engine frequencies. (he says biting his tongue )
> 
> 
> Sage


It would actually be easier to grab another pic and make that trigger the circuit, but thats in future testing.  The flyback transformer is still in "safe mode", choked on the feed side and a 12ohm resistor on the drive side just to avoid any thermal issues until I get the duty cycle and control circuit proofed. Currently its at ~30khz and only around 20% duty cycle. There are plans to eventually have it vary its own duty cycle based on load. I also have temperature feedback provisions for the driving mosfet to add in. So many of these self destruct or blow out their own hall sensors, I wanted to build a bulletproof one.


----------



## canadianhorsepower

Well well well. Another day of trying and calling and email. With some deffinite answers.
On a GM I was abble to get a 6cyl ignition module for a DIS. I wanage to simulate it with the all sensor
worked fine. When I notice this I whent ahead remove one coil and simply put a 120 60 watt bulb 
across the coil terminal then I decide to turn on my motor that buld simply exploded. All I had left
was a socketth_wtf1 happend here. I remove the light socket and decide to use a multimeter on Very 
high scale DAMN it peeking 480 volts:fan: no wonder it did "electrocute my 120 vbulb"Rof}Rof}
that was one input 480 volts. Then i did a voltage divider with a potentiometer, hook it up to the scope

and guess what it's pulsing at 6hz. Then I decide to try a single Gm module the one with 4 wires:wall:

no it didn't work I fried the module.   That was enought experimenting for today. I called my freind at BRP

trying to get a module and diagram they were using in the 80. on anything with twin cyl and one coil:shrug: waiting for him


----------



## canadianhorsepower

These can be another avenue
http://www.ebay.com/itm/KAWASAKI-75..._Watercraft_Parts&hash=item43b8f083f2&vxp=mtr


----------



## canadianhorsepower

http://www.autotap.com/techlibrary/understanding_multi-coil_ignition_systems.asp

bed table reading


----------



## stevehuckss396

canadianhorsepower said:


> These can be another avenue
> http://www.ebay.com/itm/KAWASAKI-75..._Watercraft_Parts&hash=item43b8f083f2&vxp=mtr



Those are the same avenue. That looks like what I have. Could be the exact same coil.


----------



## Lakc

canadianhorsepower said:


> Well well well. Another day of trying and calling and email. With some deffinite answers.
> On a GM I was abble to get a 6cyl ignition module for a DIS. I wanage to simulate it with the all sensor
> worked fine. When I notice this I whent ahead remove one coil and simply put a 120 60 watt bulb
> across the coil terminal then I decide to turn on my motor that buld simply exploded. All I had left
> was a socketth_wtf1 happend here. I remove the light socket and decide to use a multimeter on Very
> high scale DAMN it peeking 480 volts:fan: no wonder it did "electrocute my 120 vbulb"Rof}Rof}
> that was one input 480 volts. Then i did a voltage divider with a potentiometer, hook it up to the scope
> 
> and guess what it's pulsing at 6hz. Then I decide to try a single Gm module the one with 4 wires:wall:
> 
> no it didn't work I fried the module.   That was enought experimenting for today. I called my freind at BRP
> 
> trying to get a module and diagram they were using in the 80. on anything with twin cyl and one coil:shrug: waiting for him


Rule of thumb is that with any automotive coil you expect a 450v primary kick.
 Just like with fuel injectors, some of the newer OBD systems use Zener diodes to actively check the coil status. Although 75v is what you usually get from an injector.


----------



## Lakc

stevehuckss396 said:


> Those are the same avenue. That looks like what I have. Could be the exact same coil.


Thats yoru problem, they are jetski coils, they only work underwater


----------



## stevehuckss396

Lakc said:


> Thats yoru problem, they are jetski coils, they only work underwater



Snowmobile and Jet ski coil. So it should work under water and in the snow.


----------



## Lakc

If this is what it looks like installed, which makes sense as there were no spark plug boots or terminals, and assuming this outfit isnt putting their own ignition system in it, that box looks like it says CDI... Never heard of a CDI "only" coil before, but its beginning to look like a possibility.


----------



## canadianhorsepower

> [/QUORule of thumb is that with any automotive coil you expect a 450v primary kick.
> Just like with fuel injectors, some of the newer OBD systems use Zener diodes to actively check the coil status. Although 75v is what you usually get from an injector.
> __________________
> TE] all other system from Gm works on 12 volts


----------



## canadianhorsepower

stevehuckss396 said:


> Snowmobile and Jet ski coil. So it should work under water and in the snow.


 
Steve I agree with you ,a coil is a coil it dosn't know what turn it on

just like men, a men is a men and no one know's what turn them on
brunette or blondyRof}Rof}


----------



## Lakc

canadianhorsepower said:


> Rule of thumb is that with any automotive coil you expect a 450v primary kick.
> Just like with fuel injectors, some of the newer OBD systems use Zener diodes to actively check the coil status. Although 75v is what you usually get from an injector.
> __________________
> 
> 
> 
> all other system from Gm works on 12 volts
Click to expand...


It all works on 12 (14.7) volts. But to be emissions compliant they use the backward kick from the coils to tell the ECU that it fired correctly. Usually a zener diode breaking down which charges a small cap to allow a digital input pin to register the event took place properly.

Steve, if this is a special coil for a CDI system, the circuit your working might not be able to fire it. There are a bunch of transistorized automotive coils that could take its place, or hopefully my planB will be ready soon. My mkI system should fire it, and your welcome to try that this weekend if you like. MkII is firing, and I straightened out the cap charge in software tonight, but its not ready for prime time yet.


----------



## Lakc

http://www.sportdevices.com/rpm_readings/CDI_and_TCI.htm

Well, at least according to that site, they do make special coils for CDI. I have a nice museum piece General Radio induction meter, will be interesting to see exactly what that coil is made of.


----------



## canadianhorsepower

Lakc said:


> http://www.sportdevices.com/rpm_readings/CDI_and_TCI.htm
> 
> Well, at least according to that site, they do make special coils for CDI. I have a nice museum piece General Radio induction meter, will be interesting to see exactly what that coil is made of.


 
My GM coil have .6 ohms


----------



## stevehuckss396

This weekend is bad. Have to cut over a UPS system at a data center and it will be a "late night when computer traffic is low" kind of thing.


----------



## canadianhorsepower

stevehuckss396 said:


> This weekend is bad. Have to cut over a UPS system at a data center and it will be a "late night when computer traffic is low" kind of thing.


 

burk,   Steve . why dont you try soldering or making a why of ht wires
and run a regular coil and see what happen. After all that nasty coil beside
being a CDI unit its plain coil with 2 out. And theory should make it spark where teir is gas and air not only air


----------



## dsage

CHP:

Maybe I mis-understood what you wrote but:
If you fire both plugs with a HV Wye connection from one coil, the spark will occur in the cylinder with no compression, leaving nothing for the one that requires the spark.
 Path of lease resistance. Firing a plug under compression not to mention with a fuel mixture, takes many times the voltage to fire than a plug at atmospheric pressure.
 The dual output coil expects the plug(s) to be connected between the HV leads (like a common transformer). It does not fire to ground. If you have two plugs, they are effectively in series when screwed into the same block. Being a series circuit the one with no compression fires easily passing the voltage (current) on to the other plug.

Sage


----------



## Lakc

stevehuckss396 said:


> This weekend is bad. Have to cut over a UPS system at a data center and it will be a "late night when computer traffic is low" kind of thing.


One of those "plenty of coffee nights", yeech. 
I wasnt happy with my MkI but it might just be the trick for a real CDI coil. (Or maybe your coil would be the trick for my engine?) We just need to get it working first, we can make whatever fit later.


----------



## canadianhorsepower

> If you fire both plugs with a HV Wye connection from one coil, the spark will occur in the cylinder with no compression, leaving nothing for the one that requires the spark.


 
What is the best insulation air gap, It will jump where its easier.
I agree with you If one cylinder is under compression no gas mix and the other one no pressure
and no gas mix it would take that path
gas and mix are an explosive all they are waiting for is a spark and it does not have to be big


----------



## stevehuckss396

canadianhorsepower said:


> What is the best insulation air gap, It will jump where its easier.
> I agree with you If one cylinder is under compression no gas mix and the other one no pressure
> and no gas mix it would take that path
> gas and mix are an explosive all they are waiting for is a spark and it does not have to be big




I have heard the same thing Sage has presented. I have to believe that if the Y cable worked like you say, there would be engines out there with Y cables on them. Putting the plugs in series forces the spark in the compressed cylinder.


----------



## dsage

In addition,  a fouled plug (shorted) would take the hit every time and the engine would stop instead of running on one cylinder.

Sage


----------



## canadianhorsepower

> I have heard the same thing Sage has presented. I have to believe that if the Y cable worked like you say, there would be engines out there with Y cables on them. Putting the plugs in series forces the spark in the compressed cylinder


 
What do you think your coil is doing??????????????? it does not look lyke a why but you can't judge Santa Claus because of it's suit



> In addition, a fouled plug (shorted) would take the hit every time and the engine would stop instead of running on one cylinder.


 
your write with this quote you should see what happen when a coil like Steve goes wild backfire all over the place

It sound's like off topic .............................. simply check glow plug operation on a twin.... it doesn't shut off
simply nothing to burn


----------



## canadianhorsepower

damn I hate that when those clown with question mark shows off


----------



## canadianhorsepower

I hope you realize that this is the type of plugs I was talking about


----------



## stevehuckss396

I have been looking at coils for plan E. There are dual coils that are 1.5 to 5 ohm and some of them say "for points" Should I just eat this coil and get a 3 or 4 ohm coil? That might solve the entire problem other than the mounting of the coil. I could try this circuit or maybe build the circuit Les posted and see what happens. They are about 55 bucks. Seems reasonable.


----------



## dsage

I think you already proved that the circuit you have will drive a coil that is "normal" so there seems no need to re-build what you have as a driver at least to get you going. If I remember correctly Les' circuit was not significantly different, just possibly more fault tolerant. None of the circuits are going to blow a coil meant for 12v (unless you leave it on for a long time).
 Where are you looking up the coils? Seems reasonable that if it says "for points" then it's a more conventional coil and it might work.
Are they available from places like Autozone etc?
You could buy, try and return if unsuccessful. (Check the return policy though). Not sure about what resistance would be good. Two ohms would be reasonable. The circuit as-is should drive 6 amps ok.

Maybe give Lakc's CDI unit a try on the bench. That'll tell you more about the coil you have.

(Yah I know not much help)

Sage


----------



## canadianhorsepower

stevehuckss396 said:


> I have been looking at coils for plan E. There are dual coils that are 1.5 to 5 ohm and some of them say "for points" Should I just eat this coil and get a 3 or 4 ohm coil? That might solve the entire problem other than the mounting of the coil. I could try this circuit or maybe build the circuit Les posted and see what happens. They are about 55 bucks. Seems reasonable.


 

yes  yes  yes 
and the rest of it, put in a BIG book of experience or grey hair:hDe:


----------



## stevehuckss396

I am going to wait for Lakc but if what he has wont drive this coil because this coil is'nt meant for a 12 volt primary I am going to need a plan B or C or maybe D?  Just looking ahead a little bit.


----------



## dsage

Always good to be looking ahead. You have nothing to lose. Buy the coil if you think it will work. You build enough engines that you'll use what's left over at a later date.

Sage


----------



## GailInNM

Steve,
If you get down as far as plan G, take a look at the CDI unit from CNCengines that you have used on another engine in the past.  The early ones from them had  both ends of the  high voltage winding available.  A couple of years ago they grounded one of them internally in the coil so only 3 terminals are available on the coil instead of the 4 that were available on the early ones.

If yours has all 4 terminals available on the coil, just lift the ground connection that is on one end of the high voltage winding and run it to your second plug.  I looked at my coil and both ends are insulated equally so lifting the second end above ground will cause no problems. 

Last night I modified one on one of my single cylinder engines and set up a dummy second spark plug with an adjustable gap to check it out. Engine runs same as before as I varied the adjustable gap from zero (shorted) up to 1/4 inch which was the maximum I could set the adjustable gap to.  Nice lively second spark in the dummy plug gap all the time.

The last ignitions I got from Roy all had the 3 terminal coils. That was about 1-1/2 years ago.  I presume the current crop also does.I was going to check with Roy, but he is currently having problems with Google thinking his website is infected with  some malware.  All his internal checks say it is OK but Google persists and won't let Firefox browsers (and others) onto his site.  I am not going to bug his about my little problems until he gets his problems resolved.

I, as I suspect, the current coils only have 3 terminal, he may have some of the old coils there as replacements as he did sell them on his site in the past.  Only a few minute job to change out a coil if he does.  Of course if your old system has one of the 4 terminal coils you could use it and replace it with a new system.
Gail


----------



## Lakc

If you want to get together tomorrow afternoon just drop me a line. I work till 5ish at 12/Haggerty


----------



## stevehuckss396

I was just looking at my stash box a few days ago and I do have a coil in the box so I can do that. I will wait to see what Jeff comes up with as I really want this thing to run off the dual coil. Looks more like a v-twin with the current coil.


----------



## stevehuckss396

Lakc said:


> If you want to get together tomorrow afternoon just drop me a line. I work till 5ish at 12/Haggerty



This week is going to be bad. I am displaying at the Detroit Autorama and I have some things I have to do to get ready.


----------



## Lakc

No problem, whenever you get a chance.
I must be getting old, I remember Autorama being on Daytona weekend.


----------



## canadianhorsepower

Detroit is the 8-10 isn't ???


----------



## stevehuckss396

canadianhorsepower said:


> Detroit is the 8-10 isn't ???




What do you mean 8-10?


----------



## canadianhorsepower

stevehuckss396 said:


> What do you mean 8-10?


 the 8th and 10th of March


----------



## stevehuckss396

canadianhorsepower said:


> the 8th and 10th of March




You mean the Autorama dates!  Yes it is the 8th - 10th. I will most likely go down Saturday the 9th.


----------



## canadianhorsepower

stevehuckss396 said:


> This week is going to be bad. I am displaying at the Detroit Autorama and I have some things I have to do to get ready.


 
I was under ste impression that you were going their this weekend


----------



## stevehuckss396

Nope.  Working this weekend


----------



## Lakc

The weekend before Autorama is the busy time. A good friend of mine has a sheet metal shop, and gets a significant amount of last minute business up until Wed night for move in.. Of course, he got more of it when we were building his cars to that same deadline. 
Lest I digress too much about old racing days, which are much better conversations to have in person over an adult beverage, tonight's goal is to have MkII soldered together on a pair of circuit boards. Debugging is basically done and board design for emf protection is next.
MkI is still available for trials if you have an itch. Sat afternoon I have an engagement but remainder of weekend is for getting things accomplished. 96/Inkster.


----------



## jgedde

dsage said:


> The circuit you posted is a poor variation of the "old school" TIM circuit. A hall sensor in theory will activate it but the resistor values on the front end are pretty low value and depending on the sensor it might not be able to drive the circuit and/or may damage the sensor. The problem with all of the original TIM circuits is the output transistor breakdown voltage. In order for a coil to work properly you must not supress the kickback voltage generate on the primary side of the coil when the "points" open. When you use conventional points there is no problem since the points gap is quite large.
> In the case of the TIM circuit the transistor breakdown voltage is perhaps (unchecked for the particular transistor) 150volts at most. This will limit the seconday Hi voltage to 150v x the turns ratio of the coil. Typical turns ratios are about 100:1 therefore the secondary will only get to 15kv. That's probably more than enough for a model engine but you can do better.
> 
> Try my circuit below. It has the following improvements:
> 1. The front end is designed for a Hall sensor.
> 2. The first stage does not sit around consuming a lot of power when the engine is not running. The circuit you presented consumes considerable power just sitting there doing nothing.
> 3. A big problem with all of the TIM circuits was that it was possible for the engine to stop with the ignition activated which could (usually did) burn out the coil and or transistor or both. This circuit will not do that.
> 4. Most important is, this circuit uses a proper IGBT transistor to drive the coil. One that is made specifically for this purpose for automotive ignition systems. It has a very high breakdown voltage.
> 5. A little extra benefit is the LED which blinks when the Hall sensor is activated so you can tell if there is activity.
> 6. The input circuit can be run on the same 12v as the rest of the circuit but need not be. Just be sure the ground is common to both supplies.
> 7. And the best part - the IGBT is a logic level input device so, if you are so inclined you can elminate the front end altogether and drive the IGBT base with a microprocessor or logic chips.
> 
> Note that the symbol for the IGBT transistor is not precise. It's drawn like it is to make if familiar to the original circuit. The IGBT is a TO220 device so you'll need to consult the spec sheet to get lead orientation.
> 
> With a little ingenuity you should be able to use your existing circuit board by leaving out components and perhaps cutting traces and adding jumpers.
> 
> 
> [EDIT Feb. 22 2013]
> Updated drawing. I had the wrong part number variant for the IGBT transistor. Sorry. All is correct now.
> 
> Sage


 
Sage,

I didn't appreciate how good your circuit was until I sat down to design my own.  When I first looked at it (and commented - incorrectly) I didn't notice that you were using an IGBT (since it's drawn as a BJT).  That would've grabbed my attention for sure! 

I then I forgot all about it!  Including my remark about AC coupling the input to prevent the battery from being drained (and coil potentially cooked) if the engine stopped with the coil stuck on.  Ugh.  My short term memory is cooked...  I could have saved myself quite a few hours of design time.

Now that I have my circuit under my belt, I am surprised how close my input circuit is to yours.  Then again, there are only so many ways to skin a cat.

I think the only advantage my circuit has is reduced power consumption.  My design doesn't need to draw current to keep the output IGBT off.  

My circuit is posted here: http://www.homemodelenginemachinist.com/f31/new-ignition-circuit-20415/index2.html#post214570

Cheers!
John


----------



## dsage

Great  minds think alike I guess.
 I posted a couple of comments / questions on your other thread.

Sage


----------



## jgedde

dsage said:


> Great  minds think alike I guess.
> I posted a couple of comments / questions on your other thread.
> 
> Sage


 
I don't see any posts from you in that thread.  I'm curious what your comments and questions are...

Bear in mind the circuit hasn't been built yet.  Still waiting for parts from Digikey.  While it simulates fine in PSPICE, I learned that PSPICE often lies!

My main concern (that may be too strong a word)  is the values of the resistors in the input network.  I'm not 100% convinced PSPICE is modeling the Hfe of Q1 correctly for saturation.  I don't have my old Motorola databook here at home which has all of the related info (overdrive factor, hfe vs Vce etc) - stuff that's no longer part of datasheets today.  Why, I don't know....

Thanks!
John


----------



## dsage

Things are fast an furious over there. My comments were quickly buried by others.
http://www.homemodelenginemachinist.com/f31/new-ignition-circuit-20415/index2.html#post214570

 Post #19

Sage


----------



## jgedde

I found that old appnote from TI.  Here is is:  http://www.ti.com/lit/ml/slup169/slup169.pdf

It's and oldie but a goodie and well worth the read.  IGBT gate drive is much the same as MOSFET gate drive.

John


----------



## dsage

Check out the TC4426 /27 /28 from Microchip. It's a dual high power (1.5A) MOSFET gate driver. I've used those. They work really well. Does away with all the discrete stuff.  But then that's another 8 pin DIP component to add to the design.

Sage


----------



## jgedde

dsage said:


> Check out the TC4426 /27 /28 from Microchip. It's a dual high power (1.5A) MOSFET gate driver. I've used those. They work really well. Does away with all the discrete stuff.  But then that's another 8 pin DIP component to add to the design.
> 
> Sage


 
Those a great IC's.  I've used them a lot!  Also the 4424 and 4425 drivers.  The nice thing more me is that Intersil makes them radiation hardened for space electronics.  

The other IC I like to use is the International Rectifier IR2113 dual high/low gate driver IC.  That bugger allows you to use identical N-channel MOSFETs in a totem pole.

John


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## Lakc

stevehuckss396 said:


> OK here is the deal


Still trying to figure this out, those dimensions dont quite add up. Whats the bolt circle diameter and size?


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## canadianhorsepower

1.850 +.250 = 2.100


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## stevehuckss396

Yes!  2.100


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## Lakc

I think I can squeeze it in, but its gonna be tight. A 1uf cap at 450v is not a smd component, and neither is the 1.25&quot; toroid I am using at present.  The depth is almost certainly going to be a violation. I will see if I can get a board made today or tomorrow.


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## canadianhorsepower

Lakc said:


> I think I can squeeze it in, but its gonna be tight. A 1uf cap at 450v is not a smd component, and neither is the 1.25&quot; toroid I am using at present.  The depth is almost certainly going to be a violation. I will see if I can get a board made today or tomorrow.


 
Will you post the circuit on here or make it availlable to member


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## Lakc

canadianhorsepower said:


> Will you post the circuit on here or make it availlable to member


If I ever get the design down to a science instead of a "black art" its possible I might sell them. Flyback transformers at this voltage level are pretty touchy, and parasitic capacitance effects make it unlikely to be an easy project to complete as published.


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## stevehuckss396

Before you get too carried away did you want me to drop off the coil and other components so you can test everything before you spend alot of time making boards.


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## Lakc

I have another coil here, 1 of a 3 pack for GM distributorless ignitions. It gives a hell of a spark and should be an easy replacement on your engine if need be. I dont have any real doubt that you have a CDI style coil, and this should spark it just fine.


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## stevehuckss396

Sounds good!  Let me know if there is something I can do to help.


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## Lakc

Finally, not too shabby. My first attempt at a genuine photoresist board. Bought the boards two years ago as emergency stock, my guess is the chemicals were at least good enough. Ran out of toner, had to ebay that, and some transparencies as well, and had to wait all week for them to arrive. Mcmaster provided a yellow darkroom bulb, a nice piece of 1/4 thick glass to hold everything flat, and the local home depot provided a grow lamp bulb for the exposure. Then, a last minute dash to Meijer for a container of lye to use for developer, cut the bottom off the board and made an exposure test strip. 13 minutes later I settled on a 6.5 min exposure time, and for what seemed like hours rocking the thing back and forth in FeCl I have this!



Tomorrow morning we drill, populate, and test it out.


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## canadianhorsepower

Nice board Thm: 
there is a much easier way and the outcome is even better
instead of using transparencies simply use real photo paper in a lazer
printer then a few minutes under the iron  to transfer your drawing and you etch
the results are crystal cleer and you dont have to worry about day light


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## stevehuckss396

Hello Jeff!

Do you have the gerber file for the board? I was just asking because CamBam can now handle them and I would like to have a file to play with.


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## canadianhorsepower

> Do you have the gerber file for the board


 
Steve, what  do you call a "gerber file"


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## stevehuckss396

Gerber files are the files that circuit board layout programs create.

http://en.wikipedia.org/wiki/Gerber_format


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## Lakc

Steve:
I think I can generate one, but never tried. I am using the free version of Eagle.

Luc:
I have three failed attempts at toner transfer here, the main problem being that I was too low on toner to get good thick coverage. Comparing the two methods, I have gotten much better resolution with the photoresist. My test strip was two PIC programming boards for SS and SSOP, and under magnification the pads and 10mil traces were unbelievably sharp. The time and effort put into soaking the paper off made photoresist much faster too. Its well worth the $1 or so extra for resist coated boards


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## canadianhorsepower

stevehuckss396 said:


> Gerber files are the files that circuit board layout programs create.
> 
> http://en.wikipedia.org/wiki/Gerber_format


 
thanks for the info, it's kind of strange I have 3 different programs
to make PCB board and none of them call it GERBER file


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## jgedde

canadianhorsepower said:


> Nice board Thm:
> there is a much easier way and the outcome is even better
> instead of using transparencies simply use real photo paper in a lazer
> printer then a few minutes under the iron  to transfer your drawing and you etch
> the results are crystal cleer and you dont have to worry about day light


 
Luc,  I've tried that myself with mixed results.  The iron never seemed to have enough pressure to get the transfer to occur.  I suspect flatness was an issue.  Any ideas?

Also, the specific printer used made a lot of difference.  The LaserJet 2035 at my desk didn't work well at all.  Then I tried it using a color LaserJet printing in black.  That worked MUCH better.  

The whole concept _really_ worked well if I passed the board and transfer paper through a laminator!  But, the thickness really taxes the laminator.

That said, Laser toner seems to work very well as a resist if you can successfully get it to transfer over to the copper.  What I do know for sure is cleanliness of the copper is of prime importance for decent results.

John


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## jgedde

canadianhorsepower said:


> thanks for the info, it's kind of strange I have 3 different programs
> to make PCB board and none of them call it GERBER file


 
A Gerber file (also known as RS-274X files) is usually generated by the layout program as a separate operation.  Since Gerber files don't know anything about the netlist or footprint information, PCB software saves the board project in its own native file.  There is one Gerber file for each layer in your board.

The downside is that a lot of freebie packages use a proprietary format that only allows you to deal with the manufacturer associated with the software.  That being the case, there is no GERBER file generator.  ExpressPCB comes to mind as an example.

So, in order to generate GERBER files, you usually have to configure the output, then command the software to generate the files as a separate operation.  I've seen it in several different programs and all manage it diffrent: 
File | Export | Gerbers, 
File | Generate Fabrication Drawings
Tools | Create Gerber Files

There doesn't seem to be any standard file extension for Gerber files.  Most PCB layout software generates a report file or a readme document that specifies what Gerber file corresponds to what feature on the board.  For example, top layer, solder side layer, intermediate layers, solder mask, silkscreen, etc.

All that said, it's up to you to specify to the board manufacturer the layer stack-up order, thicknesses of copper and prepreg, finished thickness, whether you want to cap vias, etc.  See some examples below from boards I did...  A scanned hand sketch is fine too.  Having this information zipped up with your gerbers, will save a day getting the boards fabricated since they won't have to figure it out themselves, or call you for support.

John


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## canadianhorsepower

> Luc, I've tried that myself with mixed results. The iron never seemed to have enough pressure to get the transfer to occur. I suspect flatness was an issue. Any ideas?


 
Yes ,maybe I should have mention that to:hDe: for the iron I did purchace a small soldering iron from the hobby shop. The one use to shrink the plastic on air planes wing and other stuff. It's 1/4 the size of a regular one with a nice small tip on it. Usualy I will iron for about 5 min minimum

The main reason why I prefer kodac paper is that you can use the sheet to
it's fullest , Transfer paper once it's used it's over kodac paper trans fer your circuit put it back in the printer select the area you whant to print and there you go. my 2cents of experience and love it. When I'm only trying something
I use an etch resist marker draw my circuit manualy on the copper and it,s done there's many way to kill a cat :fan:


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## Kodel

dsage said:


> 3. A big problem with all of the TIM circuits was that it was possible for the engine to stop with the ignition activated which could (usually did) burn out the coil and or transistor or both. This circuit will not do that.


6 years later and I'm rebuilding your circuit for a full scale motorcycle. The polarity of C1 has got me puzzled: isn't C1 reverse biased when the points or hall effect are open? It gets discharged through R4, R1 and U1, but it also supplies current to the base resistor of U2 through R1, sending a current through C1 that will build up a reverse voltage.
Or maybe it didn't cause a problrm in your application, feeding the circuit with 6V instead of the 14.4V that I will be feeding it.


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