A-class Preamp PSU

VR 1k must be replaced with 4k7 for BF245A, and regulation output voltage will be from +/12V to +/-24V.

Friends, good morning,

I built this PSU, and I have a problem, turning the trimmer (from 4k7), both positive and negative, the voltage increase is adjusted to 11volt, then suddenly switches to 20V just tap to get to 38V full scale. I used the bf245a. and 'too sensitive !!? I have to change trimmer?
20161210.jpg
 
Friends, good morning,

I built this PSU, and I have a problem, turning the trimmer (from 4k7), both positive and negative, the voltage increase is adjusted to 11volt, then suddenly switches to 20V just tap to get to 38V full scale. I used the bf245a. and 'too sensitive !!? I have to change trimmer?
20161210.jpg


... But, if I replace instead of 4k7 trimmer a calculated resistor for voltage +/- 24V .. ??
 
This looks like a great next step after a 317/337 supply. Higher current than the super-shunt regs and easy adjustability :D.

However, I can't find any stock of BF245A in any of the shops here, but I do have BF245B and C on hand. The original schematic, in post #1, simply specifies "BF245". I've reattached it here for simplicity.

Does the suffix not matter in this version? Or do I need to keep looking for the A variant?

Many thanks!
 

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This looks like a great next step after a 317/337 supply. Higher current than the super-shunt regs and easy adjustability :D.

However, I can't find any stock of BF245A in any of the shops here, but I do have BF245B and C on hand. The original schematic, in post #1, simply specifies "BF245". I've reattached it here for simplicity.

Does the suffix not matter in this version? Or do I need to keep looking for the A variant?

Many thanks!

....here sell Banzai Music GmbH the bf245a