[Prev][Next][Index][Thread]
Re: MOT Madness
In a message dated 5/26/00 7:38:25 AM Pacific Daylight Time, tesla-at-pupman-dot-com
writes:
<<
I just tried running two unballasted series MOTs at 4800vac with a .096uF
MMC tank cap on my 4" coil, and it was a dismal failure. It made great
sparks--for about 5 seconds. Then the spark gap formed a power arc and the
output shrank to nothing. The 1/4" copper tube primary and 6AWG wire
connections got too hot to touch. The solder actually melted on my
aligator clip tap. I think the tank current was a bit out of hand!
I had hoped that a bigger 96nF (instead of 47nF) MMC would give bigger
sparks, but they weren't much longer--maybe up to 40" (about 1 meter) max.
I got a few curved hits to the ceiling, which is about 36" above the
toroid. Can 4800vac fire a coil? Sure, but it needs more current limiting
than just the MOT shunts or the spark gap will turn into an arc welder
after a few seconds.
I'm discouraged but not defeated. I'm going to try this again with a
series inductive ballast--perhaps a MOT with the secondary shorted. I was
hoping to avoid external ballasting because I'm trying to keep it simple.
However, the tank current is simply too high.
BTW, my earlier MOT estimate of 2400vac-at-385ma is way off. I got the
voltage right, but the short-circuit current is closer to 750ma. MOTs
really aren't shunted worth a hoot.
Best Regards,
Greg Hunter
www.angelfire-dot-com/ga3/tesla
>>
Greg,
With that much seconday current available, there is a good chance your gaps
will not be able to quench. You may need to go to a forced air gap or a
rotary.
Ed Sonderman