Test a transistor good or bad , hFE test
Condition of transistor : good , bad or defective can be checked from its hFE. hFE is DC amplification and it is a the relation of Ib and Ic , hFE = Ic/Ib. Generally , hFE is amount range 10-1000 it depends on a transistor part number. Shorted , opened , defective transistor will reflect to hFE amount. We will demonstrate those case below. hFE amount also use to QC quality of transistor , compare quality of transistor from different supplier or different batch. Some model of analog multimeter and digital multimeter has specific transistor test socket.
Step to check a transistor hFE.
1. Find a transistor terminal arrangement and DC current gain from its datasheet. For example transistor part number :
2N3904 is NPN type , terminal arrangement : E-B-C and hFE = 100(min)-300(max) .
2N3906 is PNP type , terminal arrangement : E-B-C and hFE = 100(min)-300(max).
2. Insert the right terminal to the right socket and transistor type. B terminal to B socket , C terminal to C socket and E terminal to E socket.
3. In case of bad transistor : shorted , opened will display as demonstration below.
How to check electronic device
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