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DIY Stompboxes => Building your own stompbox => Topic started by: Chris Goodson on March 23, 2004, 11:23:32 AM

Title: How can I determine a GE transistors pinout w/ a multimeter?
Post by: Chris Goodson on March 23, 2004, 11:23:32 AM
Or if you know a good link explaining this..
Title: How can I determine a GE transistors pinout w/ a multimeter?
Post by: freebird1127 on March 23, 2004, 01:47:27 PM
I'm not totally sure... but I would assume that the voltage drop from the base to the emitter would be ~0.3 volts, so that might be a good place to start.
Title: How can I determine a GE transistors pinout w/ a multimeter?
Post by: aron on March 23, 2004, 02:42:38 PM
Try this link:

http://www.repairfaq.org/sam/semitest.htm
Title: How can I determine a GE transistors pinout w/ a multimeter?
Post by: Mark Hammer on March 23, 2004, 06:03:35 PM
Think of transistors as being a pair of diodes with a common junction and it gets easier.  

My old Sam's Transistor Replacement Guide (from the 70's) suggests measuring the pin-to-pin voltage drop as a way of identifying pins and good vs bad transistors.  Ge diodes will have a voltage drop of about a quarter volt.  So, if the voltage drop when you test it like a diode is a quarter volt from pin 1 to pin 3 and a quarter volt from pin 2 to pin 3, clearly pin 3 is your base.

Another way is to simply test the hfe with a DMM and look for expected values using PNP, NPN, and the pin configurations provided.  You generally won't get a desirable hfe reading until you hit paydirt as far as pin identification goes.  I use this all the time with transistors I'm too lazy to look up.

Usually, older metal-can Ge trannies have the pins opposite to what your first hunch is.  Looking at the pins with the tranny sitting legs-up in a V-formation, the leftmost pin is usually the collector and the rightmost is usually the emitter.
Title: How can I determine a GE transistors pinout w/ a multimeter?
Post by: zachary vex on March 23, 2004, 08:36:48 PM
very often the emitter has a paint mark, different spacing, or a metal tab to identify it, so after doing the other tests, you can differentiate the emitter from the collector.
Title: Any/All of the above
Post by: petemoore on March 23, 2004, 09:13:07 PM
I took a piece of perf, about 4 holes long, stuck a transistor socket in it, soldered straight wires from the bottom sticking down.
 I stick this in the DMM's Hfe tester...I find it's easier to get the tranny's checked with this method, easiest way...