Simplistic MosFET HV Shunt Regs

[Salas]

Then these are the regulators I should use?

What about the update for the protection you made on the MOSFETs? Should I use it?

Yes, but you should scale down your R3 and R4 as I wrote, those are real HV example values shown. R3 15K 2W and R4 33K 1W should do for your 60V target. For R1, I don't know your current needs, but leave 25mA extra per reg on top of your max load demand. ICCS=(Vleds-Vgs)/R1. ~2V/R1 usually with green leds. No protection Zeners are needed at your voltage levels, delete them.

 

[tpark]

I hope this has not already been asked as I have tried to read through this thread and your NJFET Phono amp, have you tried replacing the led's with either an LM336-5 or LM 329DZ. If you have are they quieter and less temperature dependent than the led's.

 

[Salas]

No I haven't bcs I don't have any.

 

[merlin el mago]

Why don't work the HV shunt with this phono Puresound P10

Just curious, the manufacturer said that works with tube shunt regulators

Thanks for help

 

[Salas]

What do you mean it does not work with it? I see a normal common cathode with resistive anode load 2 stage circuit. Can't imagine what would exclude any regulator feeding it. Just assemble your circuit as it is drawn and use PSU voltage values exactly as written on it.

 

[merlin el mago]

So I have to adjust the HV reg to 260V & to reduce till 220V I have to put a 48K resistor?

 

[Salas]

Wait, I will show you.

 

[Salas]

That will drop 40V to first stage. Use any 260V PSU you like.

 

[merlin el mago]

You are the best.

 

[Salas]

No, considering the real engineers that are members here we are just absolute beginners...

 

[merlin el mago]

I'm a pre-absolute beginners.

 

[Salas]

So correctly you decided to make a pre-amplifier.

 

[merlin el mago]

I will say "try" instead "make"

 

[merlin el mago]

I used your schematic so I added 68K & 4.7uF instead 3.3uF to drop till 220V but the voltages measurements are:

CCS 260V both channels

ECC83
between 120K & 68K must be 220V and I have
L 206V
R 206V
between 120K & C10 must be 150V and I have
L 129V
R 133V

ECC88
between 39K & C2 must be 80V and I have
L 100V
R 102V

Of course I don't have sound so don't works.

N.B. post duplicated in Puresound P10 RIAA thread

 

[TonyTecson]

did you wire that point to point?

measure your plate voltage, reading from plate to cathode....

 

[merlin el mago]

Yes wired point to point, plate-cathode measurements:

ECC88
L 99V
R 101V

ECC83
L 139V
R 143V

Thanks for help

 

[TonyTecson]

your tube sections seems to be even.....you should have sound, maybe a break in connections somewhere...please recheck your wiring's and/or have someone look at your work, sometimes he will see soemthing you might have missed...

 

[merlin el mago]

Thanks Tony

 

[Salas]

I used your schematic so I added 68K & 4.7uF instead 3.3uF to drop till 220V but the voltages measurements are:

CCS 260V both channels

ECC83
between 120K & 68K must be 220V and I have
L 206V
R 206V
between 120K & C10 must be 150V and I have
L 129V
R 133V

ECC88
between 39K & C2 must be 80V and I have
L 100V
R 102V

Of course I don't have sound so don't works.

N.B. post duplicated in Puresound P10 RIAA thread

Beyond that the noted currents are not exact, leading to different DC drops, biasing looks like working.

 

[merlin el mago]

Sorry for my ignorance, wich pin heater is the positive & negative for ECC83 because original Puresound as soldered togheter pin 4 & 5 to one heater & pin 9 to the other heater, I mind positive heater is 4 & 5 togheter?