Advancing the spark timing in a CDI Ignition system

Thread Starter

solmillin

Joined Aug 18, 2016
22
Wow ! Some real live information. Thanks a lot ! Much appreciated.

Pardon my potential ignorance, but wouldn't the magento coil be on the left of the circuit diagram above, and the hi tension spark coil and spark gap be on the right ?

Also, I've assembled sufficient stuff to test the magneto coil voltages now, so I'll be able to confirm a/c voltages.
 

Thread Starter

solmillin

Joined Aug 18, 2016
22
Here are a few photo's of my engine and magneto. Hope it helps. There are definitely only TWO wires going from the magneto to the 'CDI'. The third (white) wire is clearly marked as a 6v feed for a light if required.
 

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debe

Joined Sep 21, 2010
1,389
It depends on how you draw the circuit. I have used a circuit that replaces ignition points & condencer. This type of circuit is usualy built in to the ignition module & theres only 2 wires like yours, & is used on a lot of small engines. They usualy build the circuit in the coil then mount it on the outside of the flywheel.Using a magnet embedded in the flywheel. I am surprised that this is not how your motor was built. I don't see an easy way of making a variable ign timing with that system. Some people have been trying to build a Digital Programable CDI ignition for 2 stroke engines, in Electronic projects on electronicspoint.com Forum for some time now. Theres 154 replies & 8 pages, & its still not working. I doubt that yours is CDI ign, sounds like Chinese marketing to me.
 

tcmtech

Joined Nov 4, 2013
2,867
Wow ! Some real live information. Thanks a lot ! Much appreciated.
And? o_O

All it shows is a basic conceptual schematic of what your systems most likely designed around of which as shown has near zero practical application or adaptability in any way for doing you are wanting to do. :rolleyes:
 

ian field

Joined Oct 27, 2012
6,536
We are realy guessing as to what you have, until you provide more info such as pictures of whats driving this on the engine. This is what a solidstate ignition looks like being driven from windings under the coil.View attachment 111266 View attachment 111267 View attachment 111268
Most I've seen have a high voltage winding on the stator, the rest of the circuit is pretty much the same as a transistorised CDI.

The pick up coil is invariably separate from the generator winding and is usually excited by a "pip" on the outer circumference of the flywheel/rotor.

Its unlikely that a circuit with 0.47uF across the base of the driver transistor, would switch fast enough for the "energy transfer" style of ignition circuit.
 

debe

Joined Sep 21, 2010
1,389
I agree with you Ian about a CDI ignition system, that's why I don't think that his is. Also that circuit I posted does actualy work as I have built several of them. Its a reverse engineered circuit of an Atom ignition module to replece points & condencer on magneto ignition systems on small engines. The reason for reverse engineering is that these modules were good little units & they are no longer produced since 2005 & are very hard to find now & people still want to use them. Cost to build one $5, if you can find one $35. I don't know if enough are interested here, as ive posted step by step instructions to build on an outboard site, & some have built them. (Remove the .47uf cap & theres no spark).IGN MODULE ATOM.jpg MOD.0 CIRC.jpg MOD.14.JPG
 
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Thread Starter

solmillin

Joined Aug 18, 2016
22
I agree with you Ian about a CDI ignition system, that's why I don't think that his is. Also that circuit I posted does actualy work as I have built several of them. Its a reverse engineered circuit of an Atom ignition module to replece points & condencer on magneto ignition systems on small engines. The reason for reverse engineering is that these modules were good little units & they are no longer produced since 2005 & are very hard to find now & people still want to use them. Cost to build one $5, if you can find one $35. I don't know if enough are interested here, as ive posted step by step instructions to build on an outboard site, & some have built them. (Remove the .47uf cap & theres no spark).View attachment 111318 View attachment 111319 View attachment 111321
I for one am VERY interested in any further information. Much appreciated.
 

Thread Starter

solmillin

Joined Aug 18, 2016
22
I agree with you Ian about a CDI ignition system, that's why I don't think that his is. Also that circuit I posted does actualy work as I have built several of them. Its a reverse engineered circuit of an Atom ignition module to replece points & condencer on magneto ignition systems on small engines. The reason for reverse engineering is that these modules were good little units & they are no longer produced since 2005 & are very hard to find now & people still want to use them. Cost to build one $5, if you can find one $35. I don't know if enough are interested here, as ive posted step by step instructions to build on an outboard site, & some have built them. (Remove the .47uf cap & theres no spark).View attachment 111318 View attachment 111319 View attachment 111321
Where do the TWO wires (blue and black) from my Chinese 80cc motor magneto connect into this circuit. With my limited electronics knowledge the circuit appears 'back to front', ie. The spark and the ignition coil are on the 'In' side (left side) of the circuit. I would have expected them on the 'out' (right side) of the circuit. I'd very much appreciate an explanation of the amazingly 'simple' circuit.
 

debe

Joined Sep 21, 2010
1,389
If you realy want to know whats in your module, purchase one on Ebay as they are only $9 ea. That's what I would do if I was that interested. To work out what the component values in the Red Atom module I had to sacrifice a $35 module. My problem was the circuit was on a US patent but no values. The patent on this Atom module with a description on how it works. US4163437 Aug7 1979. & US4911126 March27 1990.
 
Here are a few photo's of my engine and magneto. Hope it helps. There are definitely only TWO wires going from the magneto to the 'CDI'. The third (white) wire is clearly marked as a 6v feed for a light if required.
Hi Solmillin
Single coil CDI..jpg
Circuit your opinion?
Resistance(P1) to change the ignition timing.
Your test circuit.

Regards nyemi
Hungary
 
I agree with you Ian about a CDI ignition system, that's why I don't think that his is. Also that circuit I posted does actualy work as I have built several of them. Its a reverse engineered circuit of an Atom ignition module to replece points & condencer on magneto ignition systems on small engines. The reason for reverse engineering is that these modules were good little units & they are no longer produced since 2005 & are very hard to find now & people still want to use them. Cost to build one $5, if you can find one $35. I don't know if enough are interested here, as ive posted step by step instructions to build on an outboard site, & some have built them. (Remove the .47uf cap & theres no spark).View attachment 111318 View attachment 111319 View attachment 111321
Hi debe
Can be used MJE5742 type transistor circuit?
Thank you in advance for your reply.

Regards nyemi
 

debe

Joined Sep 21, 2010
1,389
Posibly not as that circuit requires the transistor to have a Hfe gain of 500 minimum. Where the MJE5742 hfe is only 50-100.
 
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