Re: Primary Resonance

>From: Graham Armitage <armitage-at-tiac-dot-net>
>To: Tesla List <tesla-at-poodle.pupman-dot-com>
>Subject: Re: Primary Resonance
>>I'm finding a resonant beat between the neon leakage inductance, the
>>primary cap, and the  mains line frequency. (I'm using my numbers, I
>>don't have yours)
>That's exactly what we thought it was. As the variac is turned up the core
>saturates and this changes the beat freq.
I am of two thoughts on this: 1) your variac is saturating or 2) your
variac is acting as a buffer/(loose coupling) from the mains which
allows the beat frequency to show through. On thought 2; given the Z
to the Variac at say 20%, the stiffness of the mains is reduced,
allowing the beat frequency current pulses to be felt in the Variac

Back when I was using a 15kV 60mA neon (~4months ago;) and before I'd
blown cap 1,2 and 4. I could feel this beat freq in the handle of my
variac at around 20%. It wasn't disturbing, just unusual.

I just check my files again, I should have plotted the primary
current, I'll bet it was high! I've since changed the circuit to try
to develop a real spark gap model and it's not working. I try in the
next couple of days.

>I measured the output (projected of course) to be about 130kV so your
>modelling is excellent. It is also very similar to what I saw on the scope
>when I was testing it. I have found a way around this although it is not the
>best. I have 4 15kV 30mA trannies which should require 20nF. If I overload
>it and put 30nF I don't get the beat and can crank up the variac to full
>power and get 40"-50" white hot discharge. I don't run it for very long
>becasue it's drawing a little too much current.
Of course given this level of model/operation there is no? spark
output. Once the output terminal breaks down the air, the secondary
will load the primary and greatly reduce it's voltage. If this did not
happen, every neon would blow as soon as power was applied!
>I built a nice air quenched static spark gap which has improved performance
Yes it does.  And thanks to Richard for the design.

>But anyway, thanks for the reply it was good to see that it's
>not just my bad circuit that's causing this!

Several months ago, this? list had a long discussion of "bumping at
20%" it seemed to be observed without regard to neon or pig, gap type,
or which loose nut was behind the controls;) Just another 1 of those
stray effects.