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Re: DC TC
Tom, Gary,
Might be worth pointing out that using a transformer with
significant leakage inductance (equivalent to a separate external
inductor) like a neon can make this problem far worse.....
> > The next question is what is the best way to pulse a DC power supply
> > with out a tube? How about a DC power supply with an adjustable charge
> > rate for the capacitor bank. The discharge rate threw the spark gap
> > could be adjusted to find resonate frequency? The capacitors would have
> > to be sized correctly for the proper charge rate.
> >
>
> You can use a DC supply to power a Tesla coil, but you
> have to be very careful and make sure you use a diode or diode array that
> is capable of handling the full, worst-case reverse voltage. And
> believe me, it is higher than most people think! A 12KV transformer
> will charge the capacitor to about 16.8KV Peak. When the AC reverses
> polarity the voltage across the diode goes to 33.6KV. Stress factors
> like this represent the *minimum* that you should expect. These peak
> values will occur up to once each cycle of the main AC frequency (60Hz).
> Always multiply such values by at least 1.5 (and preferably by 2) to
> arrive at a decent safety margin. I would use a 50KV diode as a minimum
> rating for use with a 12KV transformer. In my saner moments I would
> want a rating of at least 66KV for the diode.
In some low powered DC coil expts I was able to use a boost choke to
hike a 6Volt supply to over 50Volts no problem at all at low rep
rates. A diode will keep the cap there too. This is how a flyback
inverter operates. I think Greg Leyh uses this to good effect in his
large coil power supply.
Malcolm