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Re: [TCML] MOT shunts
Hi Greg,
Thanks for the reply. I don't want more current. I thought that taking out
the shunts would prevent saturation or at least cause it to happen at a
higher line voltage. Also, instead of the high voltage flat-topping at 80
volts or so, since the magnetic flux without passing through the shunts as
well as the remainder of the core, it would all pass through the coils
thereby allowing the secondary voltage to rise a bit higher. I now have to
MOT's which yield 1600 and 1800 volts respectively, and I would like to get
a couple of hundred each more. I'm also curious as to how you determined
the required cap values. I don't think I have to worry about resonance like
when using an NST.
Dan
----- Original Message -----
From: "G Hunter" <dogbrain_39560@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Sunday, February 14, 2010 6:49 PM
Subject: Re: [TCML] MOT shunts
Hi Dan,
Subject: [TCML] MOT shunts
> Re MOT's, will removing the shunts increase the output
voltage as well as allowing more output current? The
I don't know. I've knocked the shunts out of a MOT or two, but I never
bothered with before & after measurements. I understand why you want more
voltage, but why do you want more current? MOTs provide more than enough
current already.
units I have will saturate the cores at about 85 volts, and
increasing the primary input merely increases the power
consumption while the output voltage ceases to
increase. Aside from possibly more heating, what is
the downside of driving a TC with lower voltage plus higher
You'll need a narrow gap with aggressive cooling to deal with the low
voltage, high current power supply. I've gotten good results with an
all-copper sucker gap mounted on an old vacuum cleaner motor--very noisy,
but cheap & effective. Other MOT coilers have gotten good results using
asynchronous rotary spark gaps.
You'll also need a bigger tank capacitor. A 15/30 NST needs a tank cap of
only 5 to 10nF. With a twin MOT 12KVDC supply, I use 50nF.
current. I killed my 15 kv/30ma even with a Terry
Filter in place, and can't afford $250 for a new one!
Yes, even used NSTs can get spendy due to the high shipping cost. Likewise,
most e-bayers don't know how to pack NSTs properly, and they often arrive
with broken HV bushings. Over the past 10 years or so, I've accumulated
roughly 35 MOTs--all for free. There's something very liberating about
using free junk to build an effective power supply. This is my latest
effort:
http://myweb.cableone.net/grcarhunter/stimulus_MOT.html
Best spark so far is 50" from my 4.5" x 24" coil to a garage door rail.
Thank you Dan
>
Doing it without NSTs in MS,
Greg
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