How to tell the legs of GE Tranistor

Frequently asked question on transistors: types, substitutions, how to test, use and misuse them.
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nihoneiga
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Post by nihoneiga »

Hi there,

I've got some GE transistors, they've got one short leg and two long legs. From some poking around online, I think the short leg is the base. This leaves the other two long legs: is the leg with the little tab adjacent to it the collector or emitter? I found a way to test using a mutlimeter for this but I was wondering if there is a standard, like, short leg=base, tab=emitter or tab=collector etc?

Thanks,

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Post by HydrozeenElectronics »

nihoneiga wrote:Hi there,

I've got some GE transistors, they've got one short leg and two long legs. From some poking around online, I think the short leg is the base. This leaves the other two long legs: is the leg with the little tab adjacent to it the collector or emitter? I found a way to test using a mutlimeter for this but I was wondering if there is a standard, like, short leg=base, tab=emitter or tab=collector etc?

Thanks,

How does that multimeter test work? because I have some old Russian transistors that are supposed to have a dot on them but it's just paint and on some of them it's wore off and there is no tab so it's pretty tough to tell.

thanks

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Post by Fuzzer »

You could use the diode function on your multimeter to determine, at least, which pin is the base. For and NPN is the one to which you hold the positive lead and the other two pins measure a diode drop. For PNP is the same but with the negative lead instead.

What's the way you found Nihoneiga?

Don't know how to differentiate between collector and emitter (100% reliable).
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Post by RnFR »

the tab is usually the emitter.
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nihoneiga
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Post by nihoneiga »

Thanks for all your replies. I used the guide for testing polarity at this site:
http://users.otenet.gr/~ATHSAM/theory/T ... ty_eng.htm

Thanks for the tips!

k

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nihoneiga
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Post by nihoneiga »

I've got the tungsten Trannies same as the pictures from this BYOC forum post.

http://www.buildyourownclone.com/board/ ... &sk=t&sd=a

If you look at the shot of the bottom-side of the transistor you see the three legs with the tab near the lower leg and a faint red stripe near the right right (short) leg. As RnFR mentioned the Tab is usually the emitter, and if the short/red-stripe leg is the base, that leave the unmarked leg to be the collector. Tell me if my logic is sound on this?

Thanks

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