Re: How do Atom Computer Ignition modules work?

[legendre]

I’m not Debe, but..

quote mercuryman:

DEBE, What is the minimum voltage rating for the . 47 uf capacitor. I want to keep it small.

That cap is fed from a 4:1 voltage divider, which is connected across the coil primary winding. So, the highest voltage the cap will see would be 25% of the maximum voltage developed across the primary during the flyback phase. An educated guess would put that voltage at ~400V, so the cap needs to withstand 100V +20% safety margin – call it 120V.

However, he’s also using that transient suppressor diode across the primary, which IIRC clamps at 275V – so it +may+ be that the max. primary voltage is.. ~275V. In this case, the cap could be ~70V +20% margin, or ~83V.

So you should be safe with 120V in any case, and as low as 83V with a 275V clamping diode.