How do Atom Computer Ignition modules work?

[debe]

Very neat looking.

[weedlessdrive]

quote debe:

If you go to Photo bucket debe5 there is a video of my home made module on a running Victa 2stroke lawn mower. Also pictures of my outboard with the module on to see if they worked & they do. If you want to go in to the theory of how they work, read the US patent refered to in a previous post. It has taken me over 2 years to find a suitable transistor (2SD1071) that would work in this circuit. I found on some Ignition systems the transistor would break down. To over come this I added the 15KE200A to reduce the high voltage spikes. This then made the module reliable.

How is 15KE200A soldered in? I can’t tell where the leads go to on it?
Thanks
Marty

[debe]

The white band end goes to the Collector of the transistor & the other end goes to the Emitter.

[legendre]

quote WeedlessDrive:

Garry this is Ken W’s module. I would like to see how it’s done though. He obviously has some great skills.

It looks to be built on a piece of generic proto board with plated-through holes. The letters along the edge are probably part of a longer alphabetic sequence, used to aid the builder in laying out and documenting the circuit. It may also have had a sequence of numbers printed along the other edge of the complete board.

Incidentally, the high-voltage Darlington transistors have arrived, ten pieces total. If anyone is interested in building a module, go ahead and PM me, and I’ll ship you a couple for my cost.

ETA: I have the 1N6303A / 15KE200A diodes on order, and would be happy to include them in a packet, for anyone interested in building up one or more of these modules.

[ken-w]

The proto board was found on eBay, I cut into holes16x16. Awaiting for the big diode so the layout will change a little. Still have not tested so this package might not work, still trying to figure out to mount this baby.

[debe]

What I use to test a module before seting it in resin, is I use a test unit which is an old Seagull engine with out the barrel & piston clamped in a vice. Usualy just pull it over with a starting cord is all that’s needed. When I was checking for higher speed reliability on the bench, used an electric drill to drive it. The ultimate test was the video of using it on a lawnmower for over an hour cutting grass on a hot day.

[legendre]

I went ahead and ordered 10 pcs. of the 1N6303A / 15KE200A diodes, as they are also key to the design. These should show up sometime in the next week.

Again my offer is open – if anyone wants to experiment with building module(s), I’ll be happy to send these parts out at my own cost – no markup.

[weedlessdrive]

I’m having a hard time finding the .47uf capacitor that looks like the one in the picture.

[debe]

Doesn’t matter if it doesn’t look the same, so long as its .47uf 50v should be ok. I used 100v as they were physicaly quite small.

[legendre]

Hey debe (or anyone who knows),

The batch of 2SD1071s I received are measuring with a β of around 20 on my automagic component tester. The data sheet gives one spec for β, and it’s a +minimum+ of 500.

Is this tester artifact? Perhaps something caused by the internal diodes, one of which is a Zener, tripping up the tester? The error is a factor of 25…

[Author]

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