# Coil



## Krown Kustoms (Aug 11, 2009)

Does anyone know of plans for a hand wound coil for a small engine.
I found one from browsing around one day, now I cant remember where it was.
I am working on a small 4 stroke with a custom plug (and yes I am documenting it for a series post)
It was pretty much a hand wound transformer.
thanx -B-


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## ghart3 (Aug 11, 2009)

Are you wanting to make your own coil winder and wind your own coil?

Then Bob Shores book is good place to start. http://www.bobshores.com/

Have built the coil winder and vacuum chamber for impregnating.  Wound 3 coils and probably won't wind another for standard ignition.  Maybe for a magneto.

Recommend you check out  http://www.cncengines.com/
Small ignition system and nice thing is you won't burn up a coil if your engine stops with the points are closed and you don't notice engine stopped.
Gary


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## Krown Kustoms (Aug 12, 2009)

I looked at the link and I think I figured out the windings.
I am going to assume that the core is a perminanent magnet.
It also said something about a model T those should be pretty simple to build.
I want to build every component on this build, and also use the coil as a test stand.
thanx -B-


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## Kermit (Aug 12, 2009)

The design and Construction of Induction coils. pub.1909 


http://www.megaupload.com/?d=W9WHGAFY


Lots of good info in there,
Kermit


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## Krown Kustoms (Aug 12, 2009)

Thanks Kermit that will come in handy.
I just have to dig out of it if an electromagnet or perminant magnet would be more suitable.
looks like I have plenty to read
-B-


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## DICKEYBIRD (Aug 12, 2009)

If it's a battery ignition system, the coil core is soft iron, no magnet needed. A magneto system would require a rotating flywheel magnet, yes?


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## Krown Kustoms (Aug 12, 2009)

Im not sure I follow, that sounds like a primary to a transformer.
I have read so many different things I think I have confused myself.
Do you have a schematic or an example?
thanx -B-


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## Noitoen (Aug 12, 2009)

Before piezzo lighters, I remember one with a 12v (remote control type) battery and a small high voltage transformer. It used a very small micro switch and a capacitor to create a spark. The transformer was about 10mmx12mmx12mm in size.


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## Kermit (Aug 12, 2009)

This is a coil designed with two coils, the high tension-(voltage) type. The older version is just a single coil that remains energized until you are ready to fire it; the breaking of a contact creates sparks. 

With two coils the breaking of current is still used but it creates a high voltage in the secondary coil that is directed to the plug.

I found a rather good description WITH a recommended amount and size of wire to use for the primary/secondary type of coil.

Check it:
For a coil to give a half to one inch spark in air the following notes and dimensions will give satisfactory results. The core, of a bundle of well-annealed soft iron wire, should be 7 inches long by 3/4 inch diameter. The wire must be in perfectly straight pieces, and No. 22 B.W.G. in thickness. The core is insulated with linen tape, wound on spirally in three layers, each layer well soaked in shellac varnish. The primary coil is wound directly on the insulated core, and should consist of two layers of No. 18 B.W.G. double cotton-covered wire, the length of this coil being about 6 inches, about half a pound of wire being required.

The insulation between the primary and secondary windings is of vital importance, and should take the form of a vulcanite, or fibre, tube, \ inch thick in the walls, and be a good close fit over the primary winding. At each end of the tube, hard wood, or vulcanite, cheeks are to be fitted to form a bobbin, upon which the secondary is wound. The quantity of wire to be employed for the secondary winding will depend on the length of spark desired. For a 1/2-inch spark, use half a pound; for a 3/4-inch spark, three-quarters of a pound; and for a 1-inch spark, one pound. The gauge will be the same in each case, i.e. No. 36 B.W.Gr. double silk-covered. The wire must be free from kinks, and be tested from time to time to make sure that it is continuous. When fully wound, the whole coil should be soaked in hot paraffin wax, to exclude air and damp, and improve the insulation.









Fig. 19.

An efficient condenser is required, and for the three sizes of coils mentioned above this may consist of fifty, seventy, or ninety pieces of tin foil, each measuring 7 inches by 4 inches. The condenser is to be connected in shunt across the primary contact-breaker terminals as in Figs. 19


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## Krown Kustoms (Aug 12, 2009)

ok now im back on track, all I needed was a picture.
thanks.
I work with so many different transformers at my job trying to do something simple gets all jumbled up.
-B-


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## ghart3 (Aug 12, 2009)

B, not sure we are talking the same type of coil.
Some notes I found from coils that I wound.

The core was soft steel from transformer.  Laminated section was 1/4" square.

	Page 127 of 2nd edition of "Ignition Coils and Magnetos in Miniature" by Bob Shores								
	To wind for 6 Volt Primary use 3 layers of #28 and for 4.5 volts use two layers of #26								
	Do not apply 12 volts to a 4.5 volt primary.							
	Page 99    SL will operate from 6 to 12 volts							
	   	360 turns of #28 on primary							
		12,500 turns of #44 on secondary		

	P189							
	Amp turns should be 600 to 1100 				
	More turns = less wattage
------------------------------------------------------------------

Below is specs that I used.  Interleaving of wax paper between each layer of the secondary. 
		Primary #28   3 layers			 236 turns
	Secondary #44		 	12,600 turns
	Layer	turns		12,600 divided by 236 =53


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## putputman (Aug 12, 2009)

B, give this site a try.
http://www.oldengine.org/members/durand/Otherstuff/LT Scope Pictures/LT Scope Pictures.html
There is a lot of good stuff on this site.


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## Krown Kustoms (Aug 12, 2009)

thanks everyone you have been a big help. 
I have a few old transformers, I am going to strip one for the core and break out the wire.
-B-


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