Simplistic MosFET HV Shunt Regs

[merlin el mago]

I get off the battery, now I use 470R as cathode resistor, CCS set to 12.5mA but there is a big difference between the anode voltage of each tube: left triode 125V & right triode 141.4V, it's normal or have I to use other tube with close anode voltage between triodes?

 

[merlin el mago]

Finally got to have both triodes with the same anode voltage lowering the CCS load to 12mA & 470R as cathode resistor.

 

[Salas]

Tubes don't usually directly match if not selected

 

[merlin el mago]

Só it's normal these differences between the double triodes of the same tube?

 

[merlin el mago]

Ok understood.

 

[Salas]

Só it's normal these differences between the double triodes of the same tube?

Yes, you may even see measured and matched tube pairs on offer with still different enough gm & Ip noted for each section.

 

[merlin el mago]

What's lp?

 

[merlin el mago]

Gotcha Ip = plate current.

 

[Salas]

Yes, plate current.

 

[merlin el mago]

I misread lp instead Ip, thanks Salas.

 

[Salas]

I misread lp instead Ip, thanks Salas.

But you play your LP records through Valve Itch which has Ip so you have both

 

[merlin el mago]

Yes I have both.

 

[merlin el mago]

R8 still burns, I changed R9-10 for 68K & changed Q4 for a new one, can be IRF840 damaged? SSHV2 CCS works OK.

 

[Salas]

Inspect the Vgs across R8. A healthy IRF should not show more than 4V there.

 

[merlin el mago]

Ok

 

[Salas]

See about Vbe of Q4 Q5 also

 

[merlin el mago]

IRF840 burned, soldered a new one and now is working OK.

 

[merlin el mago]

Salas will be nice to know the voltages in each position to know when is faulty, and better in the schematic (if you don't have time let me know & I do it for you and post here so you can move later to the 1st post).

 

[merlin el mago]

Just finished a new one ready to sing. Q3 still not mounted because I'm not sure if will fit on board.

 

[Salas]

Salas will be nice to know the voltages in each position to know when is faulty, and better in the schematic (if you don't have time let me know & I do it for you and post here so you can move later to the 1st post).

It should be showing this kind of rough voltage points for a 350V input 300V output classic example. See if your example follows the voltage distances.