Voltage Tripler Questions - V Regs R1,R2 and Ripple

Harpo · Nov 28, 2008

Maybe missing something, but the ground loop might come from your J4.1 to J3.4 connection.

guavatone · Nov 28, 2008

I guess I just need to try it out and see. But the way you set it up, my PS caps, HT Regulator and PWR transformer CT must go all the way through the Relay/Phantom to get to chassis. I was trying to keep HT ground closest to chassis star.

hmmm. My brain hurts from making excel sheets for load lines and grid stoppers. ???

guavatone · Nov 28, 2008

I disconnected the 20V transformer from Chassis and the Circuit works fine and heat is gone. I think it was the chassis connection.

Seems quieter than my Demeter pre, so I think it's good now.

Thanks for the Tips.

I'm close to throwing this in the BM. Not for the PS, but the tube pre.

guavatone · Jan 21, 2009

Back to the drawing board. I can't track down why I am getting only 30V doubled from a 20V CT transformer. I read 24VAC on secondary. I omitted C14 and tried 470uF caps for C11 and C12. I also tried 2 variations for Doublers. Right now, the top section is not installed and the question is just the 48V parts. Also the tripler gave me a wopping 90V....

abbey road d enfer · Jan 21, 2009

guavatone said:
Thanks Harpo, I missed the obvious. Now I have a proper calculator for adj regs. I them played with new values and came up with R5=240R giving under 1/4W. Ideally I think I want VR2 to have a series 8k2 and 1-2k trimmer.

As far as the servo mechanism, would the new RC filter help? Can I just bypass C14 with a 100n poly to help?

new mod

BTW, on the 317 datasheets they say they are using a 240R R1 and the schems have 120R :?

FWIW, I've used the TLM783 with 1k between adj and out and 39k from adj to ground, with 47uF across, on large (32+ channels) mic splitters. I had additional post filtering with 1000uF at the output, 47R and another 1000uF.
Since your transformer delivers 20Vac, a simple doubler should deliver ca. 56V unreg. That should be enough for 48v output.