NPN transistor back to basics question

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#1
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All you analog Freaks,

What is the surest/easiest bullet proof way of testing if an NPN/PNP works? I know you can measure the beta with a multimeter, but is there an easier way than that?

Thanks.

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Use an ohmmeter to check for "diode forward conduction behavior" from B to E and B to C. Reverse meter leads, make sure you have *no* conduction from B to E and B to C. Then, check for *no* conduction from C to E. If it passes these simple checks the transistor is likely good. Fried transistors often will show a C-E short.

Tom Pappano
Tulsa, Oklahoma

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Also a multimeter in resistance measurement mode can be used to measure the transistor in same way Tom described. The other reading should be higher and the other one lower. This tells which one is E and C, but I have forgotten which way it was.

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B-C resistance is usually lower than B-E - the collector area is usually larger than the emitter area.

Leon Heller G1HSM

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Thanks,Leon and Jepael. That makes sense.