[Prev][Next][Index][Thread]
Re: Coil update
From: FutureT-at-aol-dot-com[SMTP:FutureT-at-aol-dot-com]
Sent: Sunday, November 23, 1997 5:56 AM
To: tesla-at-pupman-dot-com
Subject: Re: Coil update
In a message dated 97-11-23 02:43:02 EST, you write:
<< >> Made a few changes and now getting occasional 64" sparks using
> > 1560 watts from wallplug (1750VA). I'm using a .0148uF cap,
> > 4 1/4" x 23" sec. wound with #28 wire, and a 6 1/2" x 26" toroid,
> > 20 pri. turns, potential tranny, sync gap, etc. This is my best
> > results so far at this power level.
> >
> > John Freau
> John,
> Congratulations! I need well over 3000VA to see the same sparklength.
> BTW, what are you using for a ballast?
> -- Bert -- >>
Bert,
Thanks. I use a homemade ballast that I bought from an ex-coiler.
It has about 150 turns of #12 pvc ins. wire wound on a 3" dia. PVC
form about 15" tall or so. It originally was filled with 1/2" threaded
steel rods and welding rods, but I replaced them with transformer
"I"s from old neon trannies in an attempt to reduce losses. I did
seem to save about 20 watts when using the new neon "I" lamination
core. However, I noticed that I get some thumping in the ballast at
higher powers now, I assume it's because of the higher Q that
results from using the new less-lossy core. I tried 2.5 ohms of
resistance in series with the ballast, but this didn't help. I didn't
try parallel resistance. I did find that if I just stick a pack of welding
rods on top of the neon "I" core, (the neon core doesn't reach the
top of the ballast; about 5" remain un-cored) this does a lot to
stop the thumping. I don't know if this amount of welding rods is
de-Q'ing the ballast, or if it's simply acting more as a physical
weight and holding the neon "I"s in place (they're not physically
restrained otherwise).
There's a rotary selector switch on the front of the ballast that
selects a desired number of turns, and adjusts the inductance.
If I remember correctly, the system works best at about 6 mH
of ballast inductance.
Regards,
John Freau