by Doug Coulter » Tue Mar 08, 2011 10:21 pm
I used a volt doubler and lower volt input to the CCFL as they are more efficient that way. Quiescent current goes up with volts, usually about 40 ma at 12v, down to about 10 ma at 3v.
Don't forget you need a high R in series no matter which side you take output off. That's for tube turnoff protection, and one meg is none too much, all the old circuits use 5 meg and up, some even bootstrapping that with a vacuum tube to absolutely ensure the tube won't stay lit like a neon bulb. Remember the extra capacity to ground from the larger outer electrode can also store enough energy to hurt things. No one does it that way anymore, and for good reasons. Of course, you use shielded cable for the signal side, as you can pick up lots of noise across a meg.
Some of the really old, non self quenching tubes used a design like in John Strong's book with a vacuum tube bootstrap to force the geiger tube off, those did use the cathode as part of the active circuit. You can't get one of those these days unless you make it (not hard, BTW).
If you use a volt divider -- make sure the parallel R is still over a meg (for a modern tube). Really, it's just better to mess with that on the HV supply input instead, and keep the HV-side stuff as simple and minimal as you can. More stuff at volts means more electro-statically attracted dust and other issues. Do use a large size (like 1/2 watt) so no way it can arc across the current limit resistor.
I got all those hours because those blue block caps have near to zero leakage, ditto the diodes and coupling cap. The tube was just counting my background (maybe one/second) for that, so it wasn't drawing much either.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.