10-06-2024, 05:41 PM
(This post was last modified: 10-06-2024, 05:46 PM by Mike Watterson.)
Next I'll find a box and mount the scary raw HT parts in it.
Then
1. The op-amp HT current supply side sense to give 1V out for 10mA series current through 10 or 100 ohms. Also to translate 0 to -100V to 0 to +10V
2. Put all that and pots, switches etc on / in box with leakage flash neon and second mini-LCD meter to show breakdown voltage. Add 5V supply for meters and 12V supply for FET bias. I might derive a regulated -12V or -15V as an addition or alternative to the -95 V nominal.
3. Maybe a variable + Bias supply using an LM317 (testing HV FETs, or valves with very low HT).
4. Add lamps and FETs on heatsinks
5. Final test and changes.
Note if you feed the FET gate bias pot from a scope X timebase ramp you can have a simple curve tracer. Put the 1V drive for current meters to scope Y1 and HT of Anode or g2/screen to Y2. Or whatever. Or have a ramp generator at 50Hz and feed scope X with HT.
Maybe want to add varying the -HT that supplies grid. That's slightly more complicated. A neon and capacitor would be a simple ramp generator and could be offset.
So maybe need more switches and conectors. Use 4mm wander sockets or BNC?
Not decided yet if I'll add another +HT breakdown/Leakage multipler stage. Any opinions..
Then
1. The op-amp HT current supply side sense to give 1V out for 10mA series current through 10 or 100 ohms. Also to translate 0 to -100V to 0 to +10V
2. Put all that and pots, switches etc on / in box with leakage flash neon and second mini-LCD meter to show breakdown voltage. Add 5V supply for meters and 12V supply for FET bias. I might derive a regulated -12V or -15V as an addition or alternative to the -95 V nominal.
3. Maybe a variable + Bias supply using an LM317 (testing HV FETs, or valves with very low HT).
4. Add lamps and FETs on heatsinks
5. Final test and changes.
Note if you feed the FET gate bias pot from a scope X timebase ramp you can have a simple curve tracer. Put the 1V drive for current meters to scope Y1 and HT of Anode or g2/screen to Y2. Or whatever. Or have a ramp generator at 50Hz and feed scope X with HT.
Maybe want to add varying the -HT that supplies grid. That's slightly more complicated. A neon and capacitor would be a simple ramp generator and could be offset.
So maybe need more switches and conectors. Use 4mm wander sockets or BNC?
Not decided yet if I'll add another +HT breakdown/Leakage multipler stage. Any opinions..
