Need to regulate 450v --> 300v

[Ryssen]

I want to use one transistor (mosfet?)and zeners.
the currentvis about 20mA at the 300v.
How?

[Arnulf]

Replace BJT with a MOSFET in this schematic. Add a capacitor (100 uF or so) in parallel with the zener chain if you want a "soft start" for B+ on top of regulation.

[Ty_Bower]

Don't forget a small heatsink. You're burning three watts.

[Ryssen]

Ok,thanks.

[Tetrode]

Use a 6L6.

Look at the Grommes 260A for an example.

[Gordy]

Tetrode means this one: Schematic - Grommes 260-A Tube Amplifier @ AmpsLab.com

6L6 open loop voltage reduction located near output transformer on the schematic.

[Ryssen]

Use a 6L6

Hmm,yes that way I get the heat ontop of the chassie and I get softstart,yes maybee..

[jan.didden]

Originally Posted by Ryssen

Hmm,yes that way I get the heat ontop of the chassie and I get softstart,yes maybee..

Like this:

You can use EITHER the tube or the MOSFET, whatever is your preference.

[jan.didden]

.... or with a 6582 or 6080:

and get this performance:

http://www.linearaudio.nl/t-reg-1.htm

jd

[Ryssen]

I´will use a SS rectifier and a CLC filter,is it okay to use the 6L6 before the CLC?
I mean so the CLC get a soft start..or best to have it after?