New cap test run

From:  Charles Brush [SMTP:cfbrush-at-interport-dot-net]
Sent:  Saturday, June 13, 1998 7:20 PM
To:  Tesla List
Subject:  Re: New cap test run

> Glad to hear that your coil is cranking out those big sparks again!   As
> you and I discussed last year, we have pretty similar systems.  Last Fall
> With a 6" form wound to 28" (#22 double formvar) I was up to 77".  Not up
> to the max you've achieved, but I'm still trying!  :-)  That coil has been
> in storage for the last seven months, so I'll have to see how it performs
> this summer with some tweaking.
> Zap!
> Charles Brush >>
>Sounds like we have about the same performance.  How much power were you
>inputting for 77" sparks?  What are you using for an inductive ballast?  Do
>you also use series resistance?
>Ed Sonderman


Well my best estimate would be somewhere between 3.5kW and 5kW.  The
ammeter usually stays around 13-20 amps, yet the coil can occasionally trip
a 35amp breaker when the ammeter is reading 20 amps or so (it's pulling
current in pulses after all, so it's hard to tell where the peaks are).
For current limiting I use a Miller 225amp welder with no added resistance.
This is a very basic setup consisting of a 28amp variac, welder, and two
sets of 200amp line filters on each leg.  I used to pop the breaker all the
time before I switched to a rotary gap, but now current draw is much more
even.  I was thinking of trying some resistance this summer to see if that
helped to further smooth things out.  This coil has also been rewound with
a double layer of #22 as an experiment, but I've noticed no difference in
performance.  Spark length was about the same when it was single wound.

Charles Brush

p.s. Ah what a great way to spend a rainy afternoon here in NYC...working
on a new small 6" coil in my apartment!