[sdiy] Transistor help

[René Schmitz]

Hi Ian and all,

> Good point.  Still, my multimeter hFE function shows three digits and 
> usually resolves differences between devices.
> 
> :-)
> 

Just did a little test with a couple randomly picked PNP transistors:

	Ic = 180u	Ic=0 		hFE
			(diode test)	
BC558C 	574		821		482
BC558C 	574		819		483
BC560C 	573		823		499
BC560C 	576		824		443
BC560C 	573		821		483

Also I measured two halves of a MAT02FH where all three readings did agree.

I would say wether hFE and Vbe readings do agree depends a lot on how 
the hFE in the meter is working. The larger spread of values on the 
diode test (for pairs where the 180uA reading does agree) does seem to 
be due to larger current (Rbe maybe?) My meter does run a current of 
about 1mA through the device, but it seems this is not stabilised, 
typical go no-go tester. I suppose the hFE part is no better.

Cheers,
  René

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159