Good PSU for HT upt to 15mA??

[karsten21]

Dear folks,

I search for a solid state based PSU schematic for stabilized HT of +250V with max 15mA load. Input is ~325V. It should be "silent" means high ripple rejection as possible and as best safe against shorts on output. I want to use this for a small projet to supply only one tube ( ECC82 ) in a small case. As transformers I want to use two EI 38/16 connected against each other. The "middle" voltage of both transformers I want to use to supply the filament.

First unchecked choice was an TL 783 based one. But after reading some threats about this quite old knob I rejected this. I found a few schematic using MOSFET as a linear regulator but this need lot of external parts for a good ripple rejection and stability. The "dream" is to get something like an µa78XX for 250V 🙂

Does someone of you good fellows know an schematic which fulfil my requests?

Thanks a lot!

Karsten

 

[SY]

How about a Maida regulator? Good performance, simple, excellent reliability.

 

[Merlinb]

The "dream" is to get something like an µa78XX for 250V 🙂

Somebody already dreamed it...
http://www.supertex.com/pdf/datasheets/LR8.pdf

 

[Tom Bavis]

Somebody already dreamed it...
http://www.supertex.com/pdf/datasheets/LR8.pdf

Internal current limit is 10-30 mA - use one per stage?

 

[SY]

Somebody already dreamed it...
http://www.supertex.com/pdf/datasheets/LR8.pdf

Convenient!

The datasheet is VERY incomplete- for example, there's no line noise/ripple rejection versus frequency data. And load regulation is pretty mediocre. I'll bet their next generation of regs will be just what tube guys need.

 

[mach1]

Salas simpler simplistic shunt reg.

 

[karsten21]

maida regulator

Hey SY,

THATS it!
I never heard about this name before which might be the reason why I do not find the appropiate threads here...

Thanks a lot! The tasks for this weekend are now save 😀

Best regards
Karsten

 

[Merlinb]

Convenient!
The datasheet is VERY incomplete- for example, there's no line noise/ripple rejection versus frequency data.

Given that it is limited to <20mA applications, the input ripple can be made puny even before the reg.

I'll bet their next generation of regs will be just what tube guys need.

Yeah, cuz tube amps are soooo low noise and precise

 

[SY]

Given that it is limited to <20mA applications, the input ripple can be made puny even before the reg.

Actually, one simple application would be for use as a pre-regulator before an RC network. I'd still be inclined to use a Maida, but for apps where the current draw is low, this could save a couple parts.

MY amps are low noise and precise. Reasonably so, anyway.😀

 

[karsten21]

Picture

Hey folks, hey SY

Thanks a lot again for the help to find a HT PSU. Attached a picture of the result of your tips. Works fine at Uout 230V@5mA. I can´t measre any ripple 😀

Best regards
Karsten

 

[Mr_Zenith]

As we say here in some parts of the US, "Good gooboolymoobully!!!"

...or in other words, nice work! 😀