Re: purpose of a variac?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Christoph Bohr" <cb@xxxxxxxxxxxxxxx>

Hello Q.


> well. The voltage across the capacitors can never exceed the supply
> voltage
Thats not quite the way things work. The gap will fire, even at lower
variac setting ( though in most cases not really down to just above 
zero volts ).
The voltage on the cap/gap will still rise over some cycles of the supply
frequency, this has not neccessarily something to do with resonant rise.
This beheaviour is pretty good described on Richie Burnetts website.
Basically you will notice a lower breakrate at lower supply voltage with
a static gap. With a RSG the bangsize will vary if the electrodes are
build to have minimum clearance when alligned.
However, with the input voltage set to a very low value, nothing will
happen. But depending on your configuration there might still be
charge left in tha tank cap.

best regards

Christoph