How to measure a transistors hfe?

Forum 2005-2010 (read only) General Frequently-Asked Questions
1

My DMM dose not have a built in hfe meter, so i was wondering if anyone can tell me how to go about measure a transistors hfe?

looked at this guide http://www.geofex.com/Article_Folders/ffselect.htm that keeps popping up on google, but I want to measure silicon, not germanium......and the maths is a little daunting:
just about get the (4uA)(100)(2472) = 0.9888V part, but im lost at (100E-6)*(2472) = 247mV

:o 100E-6 :o what/where is that coming from???????

please tell me there's a easer way ::slight_smile:

2

Hfe is the gain of the transistor.
You simply measure the collector current, measure the base current and divide them.
Hfe = Ic/Ib

please tell me there's a easer way

You build this project:-
http://www.thebox.myzen.co.uk/Hardware/Transistor_Tester.html

3

So I just measure amps at the collector (or power supply if its just a battery and transistor in the test circuit) and divide it by the amp reading at the base current?

4

Yes - well you asked for it simple.

You could try subtracting the leakage current if you want to be academic about it but in practical terms it makes little difference to the figure and even less difference to what you will do with the figure.