Simplistic MosFET HV Shunt Regs

[Salas]

Can there be some solder bridge or flux residue on the PCB?

 

[poty]

Merlin, is it possible to sum your actions. It's not a blog, it's a forum.

 

[merlin el mago]

Q5 gone

 

[merlin el mago]

Can there be some solder bridge or flux residue on the PCB?

I will clean.

 

[merlin el mago]

Salas to test the CCS alone it's only necessary to take off R7 and connect F+ & F0 to a 100-220R dummy load?

 

[merlin el mago]

It seems CCS works well with LV, attached pics

 

[Salas]

Salas to test the CCS alone it's only necessary to take off R7 and connect F+ & F0 to a 100-220R dummy load?

To only short F+ with F0 is enough

 

[merlin el mago]

It seems CCS works well with LV, attached pics, dummy load 220R.

 

[merlin el mago]

What's the next step?

 

[Salas]

Can put 4.7k across each 68k, feed 30V input from lab supply and see if the output can adjust to 22V on 2200R dummy. That would be a full LV test. If successful remove the 4.7k resistors and set the reg for its HV duty.

 

[merlin el mago]

OK thank you.

 

[merlin el mago]

4k7 1/4W is enough?
2K2 1W is enough?

 

[Stixx]

Ohm's law is your friend.

 

[merlin el mago]

It works!!!!

 

[merlin el mago]

Ohm's law is your friend.

Thanks to reminding me.

 

[Tubenstein]

Slave Regulator vs SSHV2

Dear Salas,
Assume the master regulator retain in the power supply, what would happen if replacing the slave regulator (the one close to signal path) with your SSHV2?

What the differences between slave regulator and your SSHV2 for this application?

Thanks!

 

[merlin el mago]

With 4K7 dummy load, CCS max reach 23,6mA and reg Vout max reach 109.5V

 

[merlin el mago]

Min, Vout 89.7V

 

[merlin el mago]

CCS works OK with low voltage and dummy load 220R, max 34mA min 19mA

 

[Salas]

Its little CCS range for Q1 & Q2 nonetheless. They usually go up to about 100mA in this arrangement. Measure R5. Is it 10R indeed? If no and its higher by mistake restore to 10R. If yes its 10R, weird CCS result if so, try 1R (1mV=1mA TP). Also check if R4 trimmer & R3 resistor are good.