H&R trannies and 4' sparks!
From: Steve Falco [SMTP:sfalco-at-worldnet.att-dot-net]
Sent: Sunday, April 05, 1998 11:41 AM
Subject: H&R trannies and 4' sparks!
It has taken me longer than expected to build my 0.08uf capacitor to go
with the H&R trannies I bought, so yesterday, John Freau generously
voluntered to bring over a collection of capacitors, rotary gaps, and a
6x26 toroid. The trannies are used without the resonating capacitors
and put out about 2500 volts apiece in this mode. I have two in series.
We first tried just adding a primary cap of 0.075uf with my static gap.
Nice, but no where near the desired behavior. Then we added John's
syncronous gap with two gaps at 120 bps and the large toroid. WOW.
Racing sparks and lots of bad behavior from being over-coupled. Time to
stuff some scraps of LDPE here and there around the secondary. After
some careful tuning, we were getting about 4' sparks while pulling about
13 amps from the 120v line. I don't have a watt-meter so I'll just call
it 1500 VA.
The transformers are submerged in oil, with part of the original
insulation removed, and strips of 0.093 LDPE added for extra insulation
around the HV terminations. I am running series 500 ohm resistors and
air wound chokes (about 18 mH) for protection. I also have a ferite
choke on the primary of the transformers, and am plugged in through a
computer-style surge protector.
Even with all the protection, my solid-state doorbell was triggering
from the RF (My wife only answered the door once before realizing what
was causing it). Also, the building alarm system went nuts. I guess I
am going to need to relocate or put some Al window screening up in the
lab for shielding. We did put some AL foil up on the ceiling to keep
from hitting the romex building wiring, at least.
Anyway, it was awesome. Thanks to all on the list for your suggestions
in getting me this far, and thanks especially to John for bringing over
all the goodies to play with. Now I am more motivated than ever to
finish the caps, and move on to building a synchronous rotary gap.