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RE: MOT Ballast for Pole Xfmr


Your next discovery will be that an adjustable inductive ballast will allow
you to adjust to the sweet spot for your coil (been there, done that)...

Brian B.

-----Original Message-----
From: Tesla List [mailto:tesla-at-pupman-dot-com]
Sent: Monday, June 12, 2000 9:45 PM
To: tesla-at-pupman-dot-com
Subject: MOT Ballast for Pole Xfmr

Original Poster: "Gregory R. Hunter" <ghunter-at-accucomm-dot-net> 

Dear List,

I've just tried a simple experiment using a pair of MOTs to ballast my
11KV/5KVA pole transformer, and results were most gratifying.  I used my
230VAC twin MOT supply and removed the voltage doublers.  I shorted the HV
output lugs of the MOTs together, and placed the two series MOTs in series
with one leg of the 230VAC going to my pole xfmr.  This setup pulls only
about 20 Amps from the mains, but spark output was the best ever--truly

Instead of 36 to 48 inch sparks with a rare 5 footer, I'm getting steady 60
inch streamers from my little 4" x 24" junk box coil.  Hits to the floor
and attic are continuous, so I must limit my runs to a few seconds to avoid
setting the ceiling on fire.

Overall performance is much better than my bulky, water cooled ballast with
9KW of immersion heaters.  Many coilers heft a 20 pound MOT in one hand,
compare it to their 300 Lb pole pig and say, "It's not big enough."  I did
a couple of months ago, and I wasted my time and money assembling a huge
resistive ballast.  Two MOTs in a package the size of a shoe box yields
much longer, brighter spark output with half the current draw of my giant
resistor.  I'm a convert.  Inductive ballasts rule.  Resistive ballasts are

I know, I know, I'm about the 300th guy on this list to discover this, and
I've read and re-read all the archived wisdom about reactive ballasts.
However, there simply is no substitute for "hands on" discovery.  The
sparks were so insane, I had to tell somebody.

Best Regards,