8 Apr
2012
8 Apr
'12
11:09 a.m.
Rob Jarratt wrote:
You have done the job pretty well in the meantime, so my information
that you have the connected LED in the wrong direction on your circuit is
proably a little late now. :-)
And yes, as Peter already wrote the polarity of the battery is depending
of what kind of Transistor you want to test. The TIP125 is PNP so my
description was correct.
Kind Regards,
Holm
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The TIP125 are
Darlington Transistors, you can't test them very good with
your Diode Tester.
Better use a small battery (between4 and 10 Volts) a samll lightbulb from
the collector to the negative pole from the battery, connect the emitter
to
the positive pole and a resistor with approx
10-20Kohms from the basis to
the negative pole. The light bulb should light up then, w/o the resistor
not.
Regards,
Holm
Holm,
Thanks for the procedure for testing the Darlington transistors. One thing I
wanted to check though. You say that the collector should be connected to
the negative pole of the battery, I thought that, conventionally at least,
collectors were connected to the more positive side and emitters to the
negative?
I have done a drawing to illustrate what I understood from your email (I
used an LED symbol for the light bulb because I did not have a simple bulb
symbol). You can view it here:
https://skydrive.live.com/redir.aspx?cid=fc758a5a91b91301&resid=FC758A5…
1301!602&parid=FC758A5A91B91301!143&authkey=!AO-F3bI24frPXbg
Let me know if that is correct.
Thanks
Rob