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H-Bridge Rotary. Was Last Erg.
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From: Andrew Chin [SMTP:chinny-at-ozemail-dot-com.au]
Sent: Tuesday, June 09, 1998 12:08 PM
To: 'Tesla List'
Subject: RE: H-Bridge Rotary. Was Last Erg.
What you are kind of describing is like a power supply I once built, using PWM (Pulse Width Modulation). I gather this is what you are trying to do to limit the current through your pole pig. You are trying to limit the average current by keeping the voltage bursts to the pig short.
Well I don't know about pigs, but when I built a PWM power supply to run directly of mains, so I could have a variable supply from 0-240VDC, I kept blowing the household fuse, until I put resistance in series with the output. It is highly likely that you will still need some ballasting with your pig.
On the other hand, I may not understand your description completely and a circuit diagram of your setup might help clarify things.
Andrew Chin chinny-at-ozemail-dot-com.au
P.S. Forgive me if this message doesn't appear to be formatted correctly.
-----Original Message-----
From: Tesla List [SMTP:tesla-at-pupman-dot-com]
Sent: Tuesday, 9 June 1998 11:34 AM
To: 'Tesla List'
Subject: H-Bridge Rotary. Was Last Erg.
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From: L.Robertson [SMTP:LWRobertson-at-email.msn-dot-com]
Sent: Monday, June 08, 1998 1:11 PM
To: Tesla Builders
Subject: H-Bridge Rotary. Was Last Erg.
Bert and all ...
Let me try to explain why I think I won't need ballasting,
even with a pig. Of course the last laugh has been on
me before, but this time I think I have an airtight case.
A short description of my setup - it has been some
time since the last go round [:-)
A variac feeds the HV transformers, as we still need
voltage control to keep things from getting out of hand.
HV AC goes straight to a diode bridge, then through an
RF filter to a storage cap, 1.8uF -at- 60 kV. The primary
resonance cap is alternately pulse charged positive and
negative repetitively by the rotary gap. This primary cap
is now 0.012 uF, so each bang takes about 1% of the
energy in the storage cap.
There is never any short across the transformer output
as there is when the gap fires on an AC coil. The faster
the rotary turns, the more times per second the small
cap is charged; and the more current is necessary to
keep the storage cap full, but the transformer never sees
intermittent low impedance loads, and thus, I say, doesn't
need a current limiter.
Except in case of component failure, where I'm hoping
a circuit breaker will do.
Cheers ...
LR