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What are some of your favourite circuit for this voltage?
Has anyone used the Linear Regs like the Supertex inc. LR8?

Comments

Boswell Tue, 04/06/2010 - 10:00

"Favourite" is stretching things a bit - I don't like precision regulating at this voltage unless I really have to. The LR8 does a good job up to 10mA of output current, which is enough for the V+ in most double-triode circuits, but not enough for a power stage. One thing I have done is to float a medium-voltage regulator up to a high potential, but you have to be very careful to surround it with diodes so it does not get overvoltage under startup/shutdown or fault conditions.

Apart from valve (tube) HT supplies, the majority of designs I have done at this voltage have been in the input end of direct off-line switching power supplies. In these cases, you are dealing in phase-controlled high frequency FET switching, for which there are reference designs and a whole raft of available devices for the purpose.

rmburrow Sun, 01/05/2014 - 19:47

Preamp regulator: Look in the UTC transformer catalog; there are schematics of tube type regulated power supplies for tube gear. For low current "cheap and dirty" using gas filled regulator tubes, two 0D3 and a 0C3, all in series, will regulate 20 ma or so at 405 v....a series resistance from unregulated HT to the VR-tube string is required. The value of the series resistor depends on the unregulated DC supply voltage, and the sum of the maximum VR-tube current and the load.

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