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Re: power supply options



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

Eric,
I will try removing the filter, and increasing the ballast. I'll of course put a simple low pass filter in my control box to try and prevent voltage spikes in my breaker box (the FCC requires a filter of some kind). My spark gap was just a synchronous rotary (spacing set at about 1/16 inch each side), but now it is a rotary with a static in series (the static was set at about 1/4 in.). The reason I switched, is because I just recently put a heavier gauge wire in my tank circuit, and I started having quenching problems. I turned it on, and almost immediately my outer 2 mots died, the spacing was obviously way too big (lousy arcs while it lasted, for like a second) (it was also very, very humid, so that probably did not help). As I am starting to run really, really low on MOTs I am taking a stab at fixing these. I removed the carbon trails with a toothbrush and some turpentine, and I put a thick coat of polyurethane all over, especially in the cracks (more coats to follow! I did not use epoxy, as polyurethane is much cheaper, and it will flow better into the cracks (methinks).). My tank capacitor is rated to 40 kV DC (tested to 45 kV), so I could (in theory) put 28.28 kV into it (MOTs can't do that easily). I'll let you guys know how it goes.
Scott


From: "Tesla list" <tesla@xxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: power supply options
Date: Sat, 28 Apr 2007 16:45:14 -0600

Original poster: "Hydrogen18" <hydrogen18@xxxxxxxxxxxxx>

I don't run mine with any filter whatsoever. If you keep killing them, I suggest trying to run it without it. Out of curiosity what spark gap lengths are you using(if you are using a static gap) for the 6 pack and 4 pack setup? I've never used much over 2/10ths of an inch total. I think the switching to 4 pack was a good idea since it should be more reliable, still have enough voltage to reliably fire a gap, and will stress the outer MOTs less. The only advantage to the 6 pack would be if you had a very high voltage rated primary cap and had similiarly designed small conductor for the primary.

Eric
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Friday, April 27, 2007 9:55 PM
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

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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.
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----- 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.

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