Re: low vs high frequency tesla coils?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Peter Lawrence by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Peter.Lawrence-at-Eng.Sun-dot-com>

	Hi Ralph, Dunckx
	I got the idea to put the two 3kv 20mil amp transformers in series from the 
	poptronics july article where they use four 4kv 30mA transformers to get 8kv 
	at 60mA.for a tesla coil.
	I am using open core France transformers with a plastic nameplate that 
	snapps off and has a date stamped on it.  I tried them in series with 
	alligator clips. there was no corona that I could see on the windings.
	Fortunately I have not seen a transformer fail. What do I have to look out 
	for. I don't want to fry my trannys but it is tempting to get the higer 
	voltage.   Could I place them in mineral oil to better insulate the 
	windings?
	joseph


Joseph,
       if your tranny's outputs are one-end-grouned and one-end-high-voltage
then yes you can series them by connecting the grounds in common and the
two high voltage ends are your supply. 

You have to connect the primaries of the trannys in parallel not series, and 
may need to swap the connections to one (just one) so that the two outputs 
are opposite polarity.

This is exactly how a 12 or 15 Kv NST is made (even 9 and some 7.5 Kv also), 
internally there are two separate secondary windings that are in series and
with a common ground.

With this configuration it is not the trannys that will blow, rather your
capacitor, if it is not up to the voltage.

ALWAYS USE A SAFETY GAP (or you WILL blow something).

-Pete Lawrence.