30KV spark voltage.
Noise on +12 DC supply can’t be avoided. This was caused by charging on CDI Charging Capacitor which was also in series with the ignition coil. I thought 0.5V noise was caused by intermittent turning on or delay of turning off of the 2 switching mosfet on h-drive circuit. (
GonzoEngineer mentioned about mosfet fast turning on and off ) I able to isolate that h-drive and mosfet circuit was working properly. I disconnect the ignition coil from charging capacitor and scope signal on mosfet. Signals were very clean.
Noise on +dc can’t be avoided due to charging of Charging Capacitor.. But this +12V was supplying transistor collector and base of trigger transistor which affect triggering of H-drive circuit.
I remember the reply post of
*steve* that use a zener diode to input of LM7805. So, I placed a 7.5V zener before the base resistor of trigger transistor. This is to clip off 0.5 volt noise riding on the trigger signal. This solved the false triggering or not triggering of H-drive circuit.
But I don’t know if 0.5V noise on +12V DC supply will cause problem in my car radio or other electronics add on project into my car. I’m still looking for the filter choke that I removed from the +12V DC circuit of my CDI. This might help reduce the “ 0.5V noise”.
Here's the picture of 0.5V noise on dc supply at high rpm. There were 4 going low pulse created by multiple firing of CDI at high rpm. Initially there were 6 trigger pulse at 800 rpm.