finding transistors pin out with DMM?

Started by peps1, October 25, 2010, 07:30:53 PM

Previous topic - Next topic

peps1

Hi, got some philips OC75 transistors with no markings (paints chipped off so no red dot) , sure I knew how to find transistors pin out with DMM?!  :-[ 

petemoore

  hfe checker socket ?
  Stick 'em in the sockets !
  one side is PNP, the other side is NPN...each side has CBEC, by using the four socket pins and turning the transistor around all ways, a number like 87 or whatever the Hfe+ leakage is should turn up a 'ballpark' number.
  That number isn't good for ballparking Hfe of transistors without subtracting the leakage from the leakage+gain which a DMM measures.
  For finding pinout it'll show some 'reasonable' number in the readout...read the socket EBC markings...there's the pinout.
For gain minus leakage we turn to GEO and RG's transistor selector circuit.
  Another way [if the DMM has no Hfe checker] is to find the B/E diode, when in 'diode test' mode [also 'beep' mode] and the polarity of meter is in the right direction across the diode, a GE transistors GE diode will show 1 GE diode drop voltage [something like .7v IIRC, data sheet]. One pin left has to be collector.
Convention creates following, following creates convention.

brett

there are many explanations of how to do this on the www
here's a typical example:
http://www.kilowattclassroom.com/Archive/AN0007.pdf
Brett Robinson
Let a hundred flowers bloom, let a hundred schools of thought contend. (Mao Zedong)