what is difference between npn and pnp transistor

[Guest]

what is difference between npn and pnp transistor

and how to meaure them. its good or not

[CHARLIE]

TRANSISTOR JUNCTIONS ARE NPN (NEGATIVE-POSITIVE-NEGATIVE) OR PNP (POSITIVE - NEGATIVE - POSITIVE) YOU CAN CHECK FOR SHORTS BETWEEN JUNCTIONS (EMMITER/BASE/COLLECTOR) OR USE A METER CAPABLE OF MEASURING THE TRANSISTOR HFE (TRANSISTOR GAIN)

[genux]

excuse me for my bad english..
For test npn you have to use a multimeter and put positive lead to base of transistor and negative to collector (you measure a value of about 600mv with doide tester) next negative to emitter and you must measure about the same value (nb a value of zero mean the transistor is KO)...
2nd you repeat the test inverting polariti of leads and circuit have to be open (high resistivity)

for pnp the same but with polarity inverted (negative in base positive in collector..600mv...ecc.

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