"Clifford Heath"

However, HOTs are very strange devices. If you just do the basic
two-diode test, you'll probably consider that a good one has failed.
That's what I did ... something to keep in mind.


** You need a " Power Transistor Tester" - published as a full construction
article in EA magazine back in May of 1988 by me. Altronics and Jaycar had
kits for it at one time.

It will reasonably accurately test the beta (or Hfe) of any power transistor
OR power Darlington pair OR horizontal deflection transistor. Very cheap
to make - uses only a few passives, a couple of red LEDs and a WW pot.

No PCB was used as it take only minutes to wire up the bits once they are
all fitted into a small jiffy box.

It will also allow close matching ( ie Vbe match) of groups of power
transistors that must operate in parallel.

Requires an external 12 volt DC source.

I would post the schem on ABSE, but like so many others I no longer have
access to the site.




..... Phil