Cheap Chinese Ignition?

[Cogsy]

In my quest for a low cost ignition for various low speed engines, I've come across cheap ignitions like these LINK but I don't know anything about them. Does anyone know if they can be put to use on our models, what voltage they require, possible to trigger with points etc.? I emailed the seller but they have no idea about the stuff they sell.

I was thinking about making up an ignition box which I could switch from engine to engine as required but if I can get a system for under $20 I can probably afford a dedicated system for each engine.

 

[raspii]

Hi Al,

From what i have read you would be able to use the coil from a setup like this with a little modification. I don't think the CDI's would be any help as they are very specific to the engine they are designed to plug into. (But i could be wrong)

If you check out this website as they have some great ignition stuff on it as well as a coilprimer.pdf which i think will answer all your questions.

http://www.model-engine-ignition.com/home/coils

Hope this helps,

From Pat

 

[raspii]

If you check out this page also it says their 12 volt coils operate ok at 6 volts for the kind of spark we want.

http://www.model-engine-ignition.com/home/coils/atv-red-coil

Hope that helps also,

From Pat

 

[vederstein]

Just one of these days I'd like to see something labeled as "Expensive Chinese" widget.

...Ved.

 

[BaronJ]

Hi Cogsy,

Have a wander around a car or motorbike scrappers, even a petrol lawn mower coil, though some of these have magnetos. Anything that has a spark plug will have one. Almost any ignition coil will work just fine. The one you linked to with the CDI unit will work. Essentialy an ignition coil is just a transformer with a very high turns ratio. Making one isn't difficult, just tedious putting all those turns of fine wire on.

Have a look at this link:
http://www.ratwell.com/mirror/users.mrbean.net.au/~rover/ketterin.htm

 

[XD351]

The blygo unit is cdi so uses a charge coil under the flywheel and a pick up sensor to trigger the cdi .
The voltage to the cdi from the charge coil could be 100 volts or more and from the cdi to the coil as much as 600 v depending on the turns ratio inside the ignition coil .
It may be difficult to locate any old points type coils from motorbikes or even lawn mowers as points went out of fashion in the late 70s early 80 s .
I usually keep a lookout on ebay for old victa , kirby or villiers mower coils .
You can buy new victa coils but you will need the stator plate to mount it on as it has the laminated core on it .
You can buy small single coils at supercheap , i think they fit some toyota or ford cars and the are the type that has the spark plug fitting on the end of the coil , they are around 50 mm dia and 75 mm long at a guess and run off 12v .
If you are running a boxer type engine using wasted spark the old V6 commodore coil does the job.
I use the high energy ignition kit from jaycar to drive these and fit a ballast resistor so the coil doesn't cop too much current or it will burn out .
The jaycar kit can use either points or hall effect to trigger it and has adjustable dwell so you can tune it to your coil for best the spark .
If you are using points you don't need the ignition unit but i feel it makes the coil work better .

 

[tornitore45]

I did exactly what you plan, build an ignition box able to accept points OR Hall Effect and switch around to every engine I build.
I used a cheap Chinese CDI for a scooter and a fairly small CDI coil.
I found one unexpected problem, easy to solve though.
The trigger input is designed to come from a winding in the generator that create 12V. The trigger input expects a bipolar signal: Strike the spark when crossing a positive threshold and re-arm the circuit crossing a negative threshold.
It work perfectly driven with a small 6V 60Hz transformer but did not work with a contact between GND and 12V like points or Hall Effect with a pull up Resistor.
I do not recall the model for Ignition Module or Coil.

A regular coil is not the same as a CDI transformer.
A regular coil must store energy that will be released at the secondary as soon as the circuit is open. It must have a certain value of inductance to build a current in a given time.
A CDI coil is actually a pulse transformer. There is no energy stored or at least it is not the little stored energy that deliver the spark.
The energy is stored in the Capacitor at 200-400V. At the right time the Cap is connected to the Transformer simply to elevate the voltage. In the process a fast rise voltage and an oscillatory discharge is created.
Attached are the notes and measures I took.

The ignition box in in the foreground

View attachment Wood-Ignition-Box_Scooter_CDI.xlsx

 

[mcostello]

The Chinese widgets that don't work or last a reasonable length of time are already "expensive Chinese widgets."

 

[Longboy]

This is what I use between engines. A 6V scooter coil from Ebay or Amazon with 6V AA battery box w/ built in on/off switch. Fits on a board or plate about 3x7 inchs. All my gas engines are points ignition. I'm using Interloop batteries, the best NiMH rechargers you can find!

 

[Vixen]

Hi tornitore45
You seem to have found the perfect solution for my project, a V8 engine with a single hall sensor and distributor. I discovered that these Chinese CDI units will not trigger from a Hall sensor and now you have explained why, thanks for that. You say the problem is easy to solve. Can you please explain how this is achieved. I tried to download the attached file but is was garbled. I assume you made a hall sensor interface. Please can you give details of how to build the interface PCB.
Thanks
Mike

 

[BaronJ]

Basically it requires a positive 12 volt signal to cause the capacitor to discharge into the coil.

 

[fuddy699]

hi , jeff here , i do not post here often , but there was a post here here awhile ago or it may have been on another site , but the chinese unit does not last and they ended up matching it with a unit from sss machine . i have four units from sss and they can not be beat . just my thoughts .

 

[tornitore45]

Vixen, I sent you a PM to mail back directly. I could not place an attachment on the PM.