I designed this power supply using two EL36 pass tubes, and a thyristor pre-regulator. This supply should give constant current and constant voltage capability at relatively low cost.
The thyristor chopper/pre regulator should keep the voltage over the triode mode EL36 at about 100V. EL36 cathode current is in excess of 220mA continuous, so it is possible to make a 200mA supply with a single tube.
The control is just a simple cascode of two LM317AHVT to give CC/CV capability.
Please tell me what you think, i have the PCB nearly done.
Tenative specs are 1.25-400V out with TYN812 thyristors and a 400VAC 500mA transformer for 250mA DC out.
The thyristor chopper/pre regulator should keep the voltage over the triode mode EL36 at about 100V. EL36 cathode current is in excess of 220mA continuous, so it is possible to make a 200mA supply with a single tube.
The control is just a simple cascode of two LM317AHVT to give CC/CV capability.
Please tell me what you think, i have the PCB nearly done.
Tenative specs are 1.25-400V out with TYN812 thyristors and a 400VAC 500mA transformer for 250mA DC out.
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Was there a specific power transformer you've targeted (ie a Hammond model etc)?
400Vac is obviously used quite a bit in industry but all the transformers tend to be step down.
Targeting something such as 380Vdc (common SMPS DC link), or rectified mains 110 or 240Vac may make it easier to source a transformer?
400Vac is obviously used quite a bit in industry but all the transformers tend to be step down.
Targeting something such as 380Vdc (common SMPS DC link), or rectified mains 110 or 240Vac may make it easier to source a transformer?
If it's changed to full wave instead of bridge, the Hammond 278CX would be fine. If you double the tube, you can get 500mA out of it.
Firing a thyristor over a capacitive filter isn't a good idea if safe operation is desirable, IMHO.