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Re: MOT info



Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>

I wouldn't worry about the difference cost wise between 30A and 60A draw. Assuming you run it for an hour a day at ~14 kW (plenty enough to annoy/scare the neighbors/police/swat team) over a month that's $84 vs. $42 for ~7kW. I seriously doubt you'll actually run it that much before spark gaps need replaced, ears need a rest, etc. I think it's always easier to use inductive ballasting and cheaper. With caps you'd need lots of them in parallel to handle the 30-60A and you'd need lots of uF (about 100uF for around 25A limiting off the top of my head). I haven't actually tried this myself, but seems like the caps would heat up like resistive ballasting. I personnly would just use the hardware store ballast, (2) 500' rolls of 10-12 awg for 26A limiting.

Mike
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, December 22, 2004 1:55 PM
Subject: Re: MOT info


Original poster: Rich Simpson <richcreations@xxxxxxxxx>

[sorry if this shows up twice, I used the wrong email account]

I have seen the circuit that uses two mots wired back to back, then a center taped mot stack, and I have seen the circuit that grounds the "center" mots, and disconnects HV lines from the cores on the outer ones. and I have seen greg's 4 mot stack that uses caps for ballast. as well as various variations

which of these seems to be the best, for a 6 or 8 mot stack?

what about ballasting, I would rather not pull 50amps, 20-30amps would be ok (I have a 240v/60a circuit to use, but at $0.20 per kw, I would like to limit the current draw. should I use caps as greg has done, or should I wind an inductor around some rebar or welding rods?

-Rich

On Dec 21, 2004, at 11:12 AM, Tesla list wrote:

Original poster: "Christoph Bohr" <cb@xxxxxxxxxxxxxxx>

Hello Rich.

I have build a 4 and a 6-MOT stack in the past and both
performed pretty well in respect to power handling capability.

I have the MOT's under transformer oil which keeps them cold and
aids isolation. Though I did not disconnect the cores from the inner end of
the
secondary winding I had no problems with arcovers during normal operation.
I experienced a primary to core flashover in one of the outer MOT's once,
but this was after exessive voltage rise while not using a safety gap, or in
other words
this was my own fault.

I did not remove the shunts but always wondered if I had better done that.
Maybe anyone else can advise on this.
Howerever, these things are powerfull and cheap to build, but can be a pita
to
carry around, but a pole-pig isn't a lightweight neither.

regards

Christoph