> Having identified which lead is the base it is now only necessary to sort
> out which of the remaining two leads is the emitter and the other has to
be
> the collector.

Another method. Arguably less risky.
In the following R can be an eg 1 megohm resistor OR a spit wetted finger
:-)

Assume an NPN. Swap polarities for PNP.

Given XYB connection where X & Y are emitter and collector OR the opposite
and B is base.

Place meter on about 100 kohm range.
Range used MAY vary - choose one which works best for you.

Connect positive lead of meter to X
Connect negative lead to Y
Connect R from X (positive) to B
Note meter reading

Swap meter leads on X & Y
Connect R from Y (positive) to B
Note meter reading.

The lowest reading (by far) will result with positive lead on collector.

With a little practice you can do this with a multimeter on ohms range and a
licked finger.

This works because, in both cases you are applying forward bias to the base
while positive is also applied to the suspected collector. When the
transistor is 'correctly" connected the transistor has far more beta than
when reverse connected so more current flow so lower resistance.
This is an essentially fail proof test. Do be careful that wet finger does
not vary greatly in resistance between tests :-)
If you cant tell the difference then it probably doesn't matter (but you
always can).

Or you could use a boring old multimeter transistor tester.



        RM

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