wrote:
I have a 12volt home made power supply similar to Astron models. I was
told it could handle 30A. The pass transistors are missing and I have
some 50 amp NPN darlington transistors on hand I was considering using
for replacements. Can you think of any reason these could/should not
be used.

Jimmie

Tons, but all of them start with 'maybe'.

The biggest one is 'maybe your power supply was designed for straight
transistors' -- if it seems to have hefty current drive to the pass
transistor bases, then that would be the case.

Otherwise, go ahead and put in your pass transistors and see what happens.

Keep in mind that those pass transistors may be missing for a reason,
and the reason may be that the power supply never worked well in the
first place -- so if what you have doesn't work, it may be the design or
execution of your circuit, not the transistors themselves.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html