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Old 9th Jul 2020, 6:48 am   #39
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 1,006
Default Re: High voltage regulator circuit.

Originally Posted by Diabolical Artificer View Post
Thanks Dave. Is Q3/4 a current mirror? i'll try and find time to do some work on this but have a tfmr to rewind by hand today. I've noted all the IP, have a TL341 etc. Re pots across HV, the schematic I posted back in post #1 (re- posted here)uses a pot across 350v, a 470/500k. I've used two of these PSU's in a homebrew tester with no issues. i put two 10M from wiper to each end if I remember right.

Got you David, the Sussex PSU is essentially the same as the attached schematic, but uses a CCS, zener (avalanche) string to get a HV V ref then uses a potential divider instead of the pot. I only briefly tried it, saw how the zeners drifted, moved on.

Its only the early Sussex that used a chain of zeners.
"Version Nine, a daughter board (LR8 board) is mounted on main PCB which removes the series Zener Diodes, ie ZD1...ZD7 arrangement and uses a high-voltage, low-output current adjustable linear regulator (U1). to control two Power MOSFETs (TR2 & TR4) for the Anode and Screen grid voltages."
The Schematic is in this post

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