I managed to combine productive work with anachronistic play this evening.
I'm doing just a little bit of testing for a customer, that requires an RF source. The only RF signal generator that I have is this really high- tech thing from Heathkit -- I know it's high tech because it uses miniature tubes, instead of octal-based metal ones.
At any rate, the thing suffered from terrible 60Hz hum problems. I've been meaning to make a voltage regulator for the thing for years -- decades, actually. So today I went over the top, sketched the thing out on paper, and built it.
I had played with this before using an LM723, but always got stymied on the current needs of the regulator, the BIG dropping resistor I'd need, voltage shifting, and all the rest.
So this time around I realized that my solution laid in being, well, weird.
Here's the schematic, less the output cap:
+165V o-----o---------------------o-------. | | | | 33k | | | ___ | |< | .---|___|---)-----| | | | |\ .-. | | | 180k | | | | o----------o +135V | | | | | '-' | | .-. | | | | | | | | | | 150k | | | '-' | | | | | |/ \| | o-------| |-----o | |>