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How to identify the base collector and emitter of a transistor?

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Mohit Soni
Mohit Soni's picture
Last seen: 3 years 7 months ago
Joined: 31/01/2011 - 11:30
How to identify the base collector and emitter of a transistor?

How to identify the base collector and emitter of a transistor?

Qaisar's picture
Last seen: 1 month 1 week ago
Joined: 30/06/2011 - 15:47
checking transistor using

checking transistor using digital MM.


1: select diode check range

2: fix one lead of DMM (say +ve red lead) with right most terminal of transistor

3: connnect -ve lead (black) of DMM with centre terminal.

4: if DMM show any reading then u have find one PN junction.note that reading.

5: now connect -ve lead with 3rd terminal of transistor. 

6: if this also show any reading it means u have found 2nd junction also .note reading of this junction also .

7: the terminal where u connect +ve lead is the base of transistor. and other two terminals middle and left most terminal is collector and emiiter. 

8: now u have to differentiate between collector and emiiter.

9: base-emiiter junction has slighlt more resistance then collector. 

10: the terminal which has high value is emiiter and other one is collector.

11: if line 6 is not true then fix +ve lead of DMM with middle terminal and check other two terminal with -ve lead. if DMM shows reading with both terminals then follow line8,910..

12: if middle terminal show reading with one terminal and dont show with other terminal then fix +ve lead with 3rd terminal of transistor and repea process. 

13: if +ve lead dosent give u any result then repeat this process by -ve lead of DMM. 




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