Wide range discrete negative voltage regulator

[SK_Caterpilar_SK]

So I have been going arround the internet trying to find a negative voltage regulator but all that pops up is the 79xx stuff. I cant really fund a universal schematic I could use to achieve what I want. So here are the speciiffications I would like to achieve

Input voltage -130V
Output voltage : Variable between -20 and -100
Output current would be a few mA (10mA)

The purpose of this regulator is providing bias voltage for a vacuum tube amplifier.

If anyone can point me a to universal circuit I could modify to fit my needs then I would be gratefull for that too.

Many thanks

[MasterT]

https://www.eleccircuit.com/the-variable-high-voltage-power-supply-0-300v/
https://sound-au.com/project151.htm
https://www.homemade-circuits.com/0-300v-variable-voltage-current/
and
https://tubecad.com/2006/11/blog0087.htm

[SK_Caterpilar_SK]

https://www.eleccircuit.com/the-variable-high-voltage-power-supply-0-300v/
Positive voltage regulator : not what I need

https://sound-au.com/project151.htm
still a positive voltage regulator

https://www.homemade-circuits.com/0-300v-variable-voltage-current/
yet another positive voltage regulator

https://tubecad.com/2006/11/blog0087.htm
did you guess it? its a positive voltage regulator once again


I need a negative voltage regulator..one that can be scaled up. None of these are really any help to me

[aargee]

Not that I've looked for what you want, but is there any reason you can't use an isolated supply using one of the positive power supply circuits and reference positive to common/ground?

[SK_Caterpilar_SK]

Not that I've looked for what you want, but is there any reason you can't use an isolated supply using one of the positive power supply circuits and reference positive to common/ground?

Yes, its the way the power transformer is designed. its a 800VAC CT. On one side of the CT I have a 100VAC tap

[MasterT]

https://www.eleccircuit.com/the-variable-high-voltage-power-supply-0-300v/
Positive voltage regulator : not what I need

https://sound-au.com/project151.htm
still a positive voltage regulator

https://www.homemade-circuits.com/0-300v-variable-voltage-current/
yet another positive voltage regulator

https://tubecad.com/2006/11/blog0087.htm
did you guess it? its a positive voltage regulator once again


I need a negative voltage regulator..one that can be scaled up. None of these are really any help to me

Changing polarity is simple, N-MOSFET & NPN BJT replace with P-MOSFET and PNP BJT.  Turn over Zenner .