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Re: power supply options



Original poster: "resonance" <resonance@xxxxxxxxxxxx>




A good ballast for MOTs can be easily constructed with some 2 inch ID PVC plumbing tubing --- stuff / fill with 1/8th inch dia steel rod and epoxy or silicone each end shut. Wind with 200-250 turns of #12 AWG wire. You want to set your turns so that with the MOT short circuited or running a small climbing arc the max current draw is 18 Amps. This also prevents your standard 20 Amp circuit breaker from tripping.

If using two MOTs, running a separate 20 Amp circuit to each MOT and use a separate power reactor on the pri of each MOT.

Dr. Resonance




Original poster: "Mark R Dunn" <teslamark@xxxxxxxxxxxxx>


Scott:

We have discussed this off-list already, but all indications are that you
are pulling excessive current and need additional ballast on the line side
of the MOT's.  As I recall, you have been unable to measure the current draw
of your power supply or inductance of your ballast.  Also, the performance
of your coil suggests that your KVA input is quite high in relation to
what's available on your line.

I've run MOT based coils for a number of years now and the only MOT's I have
burned up were being used as charging reactors on a DC based coil.  Of
course, I am closely monitoring current draw.

A single un-ballasted MOT(shorted secondary) can easily pull 30 to 50 amps
across the line (120VAC).  You do the math for (4) or (6).

Mark



-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Friday, April 27, 2007 10:56 PM
To: tesla@xxxxxxxxxx
Subject: Re: power supply options

Original poster: "Scott Bogard" <teslas-intern@xxxxxxxxxxx>

Ok,
     I sent a reply to this message, but never
received it in my inbox, so I'll resend it.  My
MOTs are dying, and I have no clue why.  I use
mineral oil, and I float the cores on the outer
MOTs (I have been using 6, but I had so many
problems, I backed off to 4, and that worked fine
until earlier tonight.  The too biggest problems
I think it might be, is insufficient filtering,
or the fact that the transformers are just a foot
and a half away from the primary coil (and may be
having feedback induced in them).  I have safety
gaps, which don't fire since I installed my SRSG,
and the filter consists of two 50 ohm ohmite
resistors, filled with welding rods to add
"inductance".  There are also 3 strings of
ceramic capacitors, 150pf from hot to hot (in
front of the resistors) and 300pf from hot to
ground (on both sides).  I don't know if it
actually does anything, and it may be the
culprit.  I don't know, but any input would be appreciated.
Scott Bogard


>From: "Tesla list" <tesla@xxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: Re: power supply options
>Date: Mon, 23 Apr 2007 13:26:43 -0600
>
>Original poster: "Jonathan Peakall" <jpeakall@xxxxxxxxxxxx>
>
>Scott,
>
>Why not attack the problem from a different angle? Why are your MOTs >dying?
>What can you do to stop it? Maybe you could tell us what you are doing >that
>kills MOTs and maybe the kind folks on this list can help you find a way >to
>use them in a manner that does what you want and doesn't wind up frying >the
>MOTs.
>
>Jonathan
>www.madlabs.info
>
>----------------------------------------------------------------------
>Some people are like a Slinky .. not really good for anything,
>but you still can't help but smile when you shove them down the stairs.
>----------------------------------------------------------------------
>----- Original Message -----
>From: "Tesla list" <tesla@xxxxxxxxxx>
>To: <tesla@xxxxxxxxxx>
>Sent: Sunday, April 22, 2007 7:32 PM
>Subject: power supply options
>
>
>Original poster: "Scott Bogard" <teslas-intern@xxxxxxxxxxx>
>
>Greetings all,
>      Ok, I am on a students budget, so for now, a
>pig is not an option (not even one of Dr.
>Resonance's $125 pigs, I am chronically poor,
>until I graduate, and get an engineering
>job).  Right now I am using MOTs, which are free
>(which is very good), and they put out lots of
>power (which is also good) but they do indeed
>occasionally burn out, and my supply is dwindling
>faster than it is growing.  Can anybody give me
>another (very cheap) option for a nice and beefy
>HV power supply, in case I run out of MOTs before
>I graduate in 2 yrs.  I suppose there probably is
>no easy answer, but maybe somebody out there can
>tell me something to look for (or where to look).
>Thank ye kindly.
>Scott Bogard.
>P.S.  I have considered building a transformer,
>but I think it is a little beyond my skill level
>(and patience, winding stuff by hand for hours on
>end drives me absolutely crazy).  Plus I don't
>believe there is any good scrap yards near me, so
>I would have to order wire and cores and stuff,
>which I think would end up not saving me any
>money in the long run.  Thanks again.
>
>_________________________________________________________________
>Don't quit your job - Take Classes Online and
>Earn your Degree in 1 year. Start Today!
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