Re: TC's power supply

• To: tesla-at-pupman-dot-com
• Subject: Re: TC's power supply
• From: dixie-at-icenet.fi
• Date: Wed, 1 Jan 1997 17:02:01 +0000
• Subscriber: dixie-at-icenet.fi Wed Jan 1 21:16:42 1997

> 	Comment on the use of transistor switches for automotive
> ignition coils.  LOOK OUT FOR THE PEAK VOLTAGE ACROSS THE TRANSISTOR!
> I have found it can readily rise above 600 volts, without a number
> of precautions, taking out the switch transistor almost instantly
> through second breakdown.
> 	Suggestions:
> 1. Use a "snubber" capacitor across the coil primary.  It should
> start with a large value and then be reduced until it doesn't
> affect the spark output any more, watching the peak voltage all
> the time on a scope.
> 2. Always use a scope when adjusting the driver for the first
> time, keeping the voltage ratings of the switch in mind.
> 3. Always use a fuse in the circuit to avoid complete smoke
> and fire.

If transistor's voltage handling capacity is 400V, maybe I can place 
400V zener diode from transistor's collector to ground. I think it 
saves my darlington.

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