How to measure this ?

Thread Starter

Hextejas

Joined Sep 29, 2017
187
When I was trying to debug my circuit, I read about transistors and diodes that " the base-emitter junction is forward biased (meaning the base is at a higher voltage than the emitter). "
Hmmm, so how do I measure that ?
1) Power off the circuit.
2) Read the voltage:
2a) Pos on base, com on emitter
2b) Pos on base, com on ground, and pos on emitter, com on ground. Which is greater ?

Apologies for a dumb question.
 

dl324

Joined Mar 30, 2015
9,323
Measure the base-emitter voltage. For NPN, positive lead on base, negative on emitter; reverse for PNP.
 

GopherT

Joined Nov 23, 2012
8,012
When I was trying to debug my circuit, I read about transistors and diodes that " the base-emitter junction is forward biased (meaning the base is at a higher voltage than the emitter). "
Hmmm, so how do I measure that ?
1) Power off the circuit.
2) Read the voltage:
2a) Pos on base, com on emitter
2b) Pos on base, com on ground, and pos on emitter, com on ground. Which is greater ?

Apologies for a dumb question.
While the circuit is energized, red probe on base, Black on emitter. Read meter. Should be about 0.6 v for bjt.
 

Aleph(0)

Joined Mar 14, 2015
593
the base is at a higher voltage than the emitter)
That's correct for NPN bjt but if they didn't disclaim that (or cop _absolute value_ plea) then authors of resource are ignoramuses that are only worth ignoring:mad:! So just put positive lead of high z meter on base and negative on emitter. Si will be 0.5V to 0.7V and Ge should be abt 0.3V:)
 
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