Multimeter and Testing Random Transistors

[Joe Hart]

I have a bunch of cool looking transistors (harvested from various 60's-70's radios and the like) and had a few questions.  First, any suggestions on a cheap multimeter to test hfe? I found this on Amazon:

http://www.amazon.com/gp/product/B000BSHHKW/ref=pd_cp_hi_2?pf_rd_p=277661601&pf_rd_s=center-41&pf_rd_t=201&pf_rd_i=B00066ZZO4&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1ZAHR064DT8NQJAWBJ8D

Also, once I have a device to measure them, can the transistors be destroyed by putting them in incorrectly? Some of them have no markings on the cases, some do but I cannot find anything online about them, and I have no idea if they are Ge or Si. You may say, just buy what you want to use, but these are neat looking and I do like the idea of using stuff out of some radios that have some sentimental value (like the first real "boom box" that I ever had and that I used to learn how to play guitar off of -- it had a variable tape speed function).

Basically, can I just pop them in randomly until I get a "correct" hfe range reading or will I be frying 80 percent of them?

Thanks.
-Joe Hart

[petemoore]

  I've never fried a transistor in a DMM's hfe meter, everybody sticks transistors in there every way possible, N/P's.
  And that's good for finding the pinout and getting some 'relative' gain ideas, but throw them out the window for testing.
  See GEO technology of the Fuzz Face and the related Ge transistor Hfe/gain/leakage testing circuit.
  These DMM's don't factor out leakage, a big part of the 'actual gain' equation, and one good way to pick transistors for Germanium effects. The other way is to stick 'em in the circuit and see what the actual gain/leakage sounds like...look for good sound, amplification vs. noise.
  The Hfe meters work good for most bipolar transistors...useful for measuring gain of Si transistors [being low leakage].

[frank_p]

This topic also:
R.G. Explain how to find pinout with a conventional DVM.

http://www.diystompboxes.com/smfforum/index.php?topic=66097.msg524661#msg524661

[JOHNO]

That multimeter looks fine for use with stomp boxes joe. It may not be the best but it will be fine. I had a really nice fluke and i left it in my car and the heat from the sun melted it and it was ruined so i just bought a crappy 16 dollar one and its ok. While probally not as accurate as a fluke its does the job. A neat trick i use to measure transistors from old electronics equipment is to use a row of 3 sockets with solid wire soldered onto them and poke that into the meter and poke the transistors it to the socket. Because you will find that the legs on the transistors are to short to make contact when you stick them into the meter.

[rnfr]

or you can just use sockets if the leads on them are long enough.  MUCH easier than trying to jam the tranistor into those stupid holes!