This is an idea for the HT (+B) 410V supply:
Being class B, the current demand will fluctuate. Normal practice to either ignore this or to use a choke - input smoothing circuit. This is a variation on the latter, to allow use of a cheap “off the shelf” “control” transformer.
The transformer has a secondary of 415V. This is insufficient, and gives 350V (on full load). However, with a CLC filter using an 8u input cap we can get 460V. This range gives us possibilities for regulation if a controllable hybrid filter can be realised.
This is an attempt, which I will breadboard after making some “guestimates” for values.
The principle is to use use a pentode as a variable sink in series with the input cap. In fact it only conducts on half cycles, a diode clamps the other half cycle. In simulating this in PSUD2 I have assumed both cycles are controlled, so I expect some difference in practice. The pentode is driven on its screen by an inverter triode. Perhaps a triode-pentode of the ECL8X series will fit the bill. The current peaks are 50mA max.
I am interested to know if anyone has done this before.
Edit: grammar
Being class B, the current demand will fluctuate. Normal practice to either ignore this or to use a choke - input smoothing circuit. This is a variation on the latter, to allow use of a cheap “off the shelf” “control” transformer.
The transformer has a secondary of 415V. This is insufficient, and gives 350V (on full load). However, with a CLC filter using an 8u input cap we can get 460V. This range gives us possibilities for regulation if a controllable hybrid filter can be realised.
This is an attempt, which I will breadboard after making some “guestimates” for values.
The principle is to use use a pentode as a variable sink in series with the input cap. In fact it only conducts on half cycles, a diode clamps the other half cycle. In simulating this in PSUD2 I have assumed both cycles are controlled, so I expect some difference in practice. The pentode is driven on its screen by an inverter triode. Perhaps a triode-pentode of the ECL8X series will fit the bill. The current peaks are 50mA max.
I am interested to know if anyone has done this before.
Edit: grammar
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