Re: RE- Secondary wire & insu (Hull Mag )
Subject: Re: RE- Secondary wire & insu (Hull Mag )
Date: Tue, 10 Jun 1997 23:58:14 -0400 (EDT)
From: richard hull <rhull-at-richmond.infi-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
>Sounds like your getting very good output for the power on that
>little magnifier! You've broken my old 300 watt per foot of spark
>rule for small coils! Could you supply some specs on that magnifier?
> \\ ~ ~ //
> ( -at- -at- )
> Alfred A. Skrocki
> .ooo0 0ooo.
> -----( )---( )-----
> \ ( ) /
> \_) (_/
Sure. The primary is 6 turns RG-214 coax (shield is active) 12.5" in
diameter tight wound cylinder with each turn laying on the other.
3" tall. Secondary is a 10.25 Inch diameter PVC pipe section 6.5" tall
wound with #20 enameled wire. This is topped with a 12X4 aluminum spun
toroid. Coupling is K=.58 measured. With just the driver and optimal
operation as a two coil system, I can get about 3.5-4" from the toroid
grounded rod. The magnifier resonator is not formally fixed yet but the
I used for the above tests was a 3"X7" coil wound with #32 wire. It
a 10X3 toroid. The transmission line was a piece of 10 guage solid wire
long. By attaching a variable cap to the line the system can be peaked
bit. (ala Lou Balint's original work.)
The tank cap is a .0068uf capacitor. A 4C35 hydrogen thyratron is used
the spark gap replacement and is pulsed to conduction with a variable
555 circuit poping an scr which dumps a charged .06uf cap into a pulse
transformer to supply the grid of the thyratron with the 50 ohm
drive and 350 volt positive pulse of 1.4 usec duration. The thing
automatically shuts itself off during tank current reversal and the
tank current pulse is 1.1usec long with a peak value of between 100 and
amps (depending on power supply setting. To round the whole thing out,
use a 0-5KV supply with heavy HV diode bridge, a 2ufd 12KV filter cap
can supply up to 100ma. I have a large HV choke of .5 henry in series
the supply as well as a 60k ohm 100 watt resistor to limited fault
The suppliy output is fully metered.
With just the driver running, The Q is through the roof due to the rapid
I count 50 ring down cycles (at 500khz) to 25% amplitude The entire
down to smooth trace is over 250usec! When I draw a spark, the ring
over in 10usec (~5cycles), thus following the common wisdom.
Maggey #12 is in its infancy yet and nowhere near working right or
for my tastes.
Richard Hull, TCBOR