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Ignition coil to charge HV capacitors?

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Vermok

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Hello,

I just tried pulsing high voltage out of an automotive ignition coil into a capacitor (350v/3300mf), thinking it would charge it however it did not. Should it work? Why didn't it?
 
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The coil is outputting an alternating current, so it's alternately charging and discharging the capacitor. You'll need a diode (a high-voltage one) to rectify the output of the coil in order to charge a cap with it.
 
Oh thanks kpatz,

I have a 1N4004 (1A/400v) diode here so I will try that. Since the coil is outputing a higher voltage then that will it present problems?

I also have 1N4007 (1A/1000v) if thats a better choice.

Failing that what about if i pull apart my microwave, will the ~9kv diode work?
 
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What's the voltage you're getting out of the coil? If it's more than 350V, you're going to kill your capacitor.

The amount of current you'd be getting will be pretty low though, so that's why charging a big cap with the coil is taking a while.

What kind of waveform are you feeding into the coil?
 
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Sorry for slow reply.

I dont know a lot so bare with me, its being pulsed from a 12v battery through a pulse width modulator, this I guess that makes it square wave? And as for the voltage well I cant measure it but I assume its in the kilovolts.

It was my (electronically ignorant) belief that I could charge the capacitor to its listed voltage (even with a higher voltage source) without trouble as long as I didn't go over?

Anyway I just put the diode in line with the positive lead (placed in the negative lead it was giving the cap a negative charge :/). Should I have used a diode bridge?

I'm just reading about all this stuff now Diode bridge - Wikipedia, the free encyclopedia.

The actual plan was to charge a 2.5kw/1uf cap with this but I'm practicing on crappier caps I have laying around.
 
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