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Re: [TCML] mot questions
I'm not going to comment on table top designs, cos I've only built tiny coils, except from my latest which has an NST. But as to resistive dimmers, I used to use them a lot in theatres, the smallest rated at 500W, were big beasts (18inches long and about 4 inches square, the bigger ones up to 2kW were 2 ft long and about 10inches sqare) I don't think this is the way to go!
resonance <resonance@xxxxxxxxxxxx> wrote:
If you really do want a table top, portable TC, stick with a 12/30 nst as a
power source. The MOTs are heavy, usually two required, and two ballasts
also required. Nothing light or simple about this setup. A 12/30 with
spike filter is a reasonable weight for a light tabletop unit.
JAVATC will allow you to experiment with all coil parameters so you get it
absolutely right on the very first try. Amazing program, and it's free.
Dr. Resonance
Resonance Research Corp.
www.resonanceresearch.com
----- Original Message -----
From: "Neal Namowicz"
To: "Tesla Coil Mailing List"
Sent: Friday, November 30, 2007 7:19 PM
Subject: Re: [TCML] mot questions
> Let me explain why I've asked these things. I guess I'm kind of working
> backwards, in a way. I've already made a couple of "medium" sized coils
> using nst's, and those worked out fairly well for me. (Gotta do a little
> more work to improve my toploads) Now I want to down-size and make a nice,
> small relatively simple table top model. I want to keep it simple and as
> "silicon-free" as possible. That, and I have lots a mots piling up, just
> begging to be utilized somehow :) And, I want something with a decent
> current for jacob's ladders. With that in mind, let me ask a couple more
> questions-
>
> Is it logical to assume that if I use a larger mot to ballast a smaller
> one, I'll have better current limiting?
>
> Ignoring the weight/size factor, could I use 2 mots to limit one? If so,
> do I go series or parallel?
>
> I didn't realize that dimmers are solid state devices. If I can dig up an
> older one, were those simple rheostats, hence eliminating the choppy
> waveforms?
>
> These days I tend to ask more questions and/or research something as best
> as possible, rather than forge blindly ahead like some years ago when I
> first got my hands on a mot. I set up a spark gap, hooked up a fairly
> large cap, and connected it straight to line voltage. "WOW, look at the
> great sparks! Oops, why'd the lights go out? Is smoke supposed to come out
> of the transformer?" True story. Live and learn. I'm putting more emphasis
> on the live part now. Thanks again for your help and answers,
>
> Neal.
>
>
>
>>A shorted MOT ballast draws a ton of current. I have
>> a small one with a shorted secondary that draws 17A
>> and runs hot as pistol. It is barely usable. Most
>> other MOTs I've tried draw too much current for a
>> 15-20A household circuit breaker. I once used a
>> matched pair of kilowatt-class MOTs as a 240vac
>> ballast for a pole pig. With both secondaries
>> shorted, they drew 20A from my 40A garage outlet and
>> powered up my 5kva pole transformer pretty
>> efficiently.
>
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