After revisiting the ongoing project of a crude home made thermionic valve or triode vacuum tube, I decided to dispense with the old Variac-controlled adjustable 60Hz power supplies. I made a new high voltage supply using a simple flyback converter topology, followed by a high voltage linear voltage regulator made from discrete components.
The low voltage supply is still 60Hz, but it is also followed with an adjustable regulator, in this case a LM350, a 3 amp device.
The high voltage is run through a Bogen T725, with a rotary switch selecting an output tap for audio output. This can be seen in the upper left corner. The low and high voltage supplies each have their own electrical cord so I don't have to use both at the same time. I suppose switches would have worked, too.
The power supplies got their first workout in an experiment to see if I could use a silicone rubber gasket in place of the usual RTV for sealing the glass envelope of the triode. It did not work well, but that is in part due to the irregular shape of the sealing surfaces. The filament's life was short and smoky, and I was unable to receive any signals. I completely rebuilt the regenerative radio set for these experiments, so I do hope I didn't miss-wire something. It could also be the fact that I'm attempting to use grid-leak biasing this time around, whereas in the old setup I used a separate variable bias supply for the grid (+/- 17Vdc IIRC).
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