[zzz]

Kevin Gilmore's amp for electrostatic headphones (http://www.headwize.com/projects/sho...lmore2_prj.htm) requires a +580V, +-350V power supply and he provides the schematic for such PS. The problem is that I could not find one of the transistors he uses (2SA1968) anywere. And while I know what transformer does, what diode `loop` does, what these caps and zener diodes are for, I have no clue what the transistor/resistor blocks are supposed to be doing. And because of that, I have no idea what could serve as a sensible replacement for that 2SA1968...

Gurus, help

.

Another question: do you put zener diodes in series to get a zener with larger breakdown voltage? I guess this question is too basic to be even considered anywere (need to get 350V and have 200V and 150V)...

 

[Budgie]

The parts you mention are the pass transistors for the power regulation. You should be able to use a similer transistor without problems. Try cross referancing to find a new part. You could try e-mailing Kevin to see if he has a recommended replacement. You can stack zener diodes.

 

[zzz]

Thanks, man... There aren't any replacements really, there just aren't that many other 900V PNPs around. But apparently according to Kevin 2 paralleled 2SA1156 would do just fine. I guess it is the wattage that was more important here.

 

[jarthel]

Kevin is so helpful. It's so nice to build his amps.

Jayel