Good PSU for HT upt to 15mA??

karsten21 · 30th September 2010, 02:28 PM

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 · 30th September 2010, 02:33 PM

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

Merlinb · 30th September 2010, 05:41 PM

Quote:

Originally Posted by karsten21

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 · 30th September 2010, 08:26 PM

Quote:

Originally Posted by Merlinb

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

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

SY · 30th September 2010, 09:53 PM

Quote:

Originally Posted by Merlinb

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 · 30th September 2010, 11:11 PM

Salas simpler simplistic shunt reg.

karsten21 · 1st October 2010, 08:37 AM

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 · 1st October 2010, 12:27 PM

Quote:

Originally Posted by SY

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.

Quote:

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 · 1st October 2010, 01:09 PM

Quote:

Originally Posted by Merlinb

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 · 16th October 2010, 11:58 AM

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

30th September 2010, 02:28 PM	#1
karsten21 diyAudio Member Join Date: Jan 2010 Location: Germany	Good PSU for HT upt to 15mA?? 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

30th September 2010, 02:33 PM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	How about a Maida regulator? Good performance, simple, excellent reliability. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

30th September 2010, 11:11 PM	#6
mach1 diyAudio Member Join Date: Sep 2004 Location: Brisvegas	Salas simpler simplistic shunt reg. __________________ Au rutti wop-bop-a-loom-bop-a-boom-bam-boom - Richard Penniman

1st October 2010, 08:37 AM	#7
karsten21 diyAudio Member Join Date: Jan 2010 Location: Germany	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

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