[sdiy] 2N3808 dual pnp

[ChristianH]

On Sat, 29 Mar 2003 13:55:44 +0100 René Schmitz wrote:

> Hi Ruud and List,
> 
> first you need to determine which one is the base. If your scope has a
> curve tracer this is fairly easy, just try all possible combinations.
> Compare the traces to a known transistor to see what the curves look
> like. The connections of BE and BC look like a diode, because the
> transistor is made up internally of two diode junctions. The polarity of
> the junctions tell you whether it is a NPN (base is Anode) or PNP (base
> is Kathode). You can also determine this with a DVM which has a diode
> tester, but that doesn't tell you anything about which is the collector
> and emitter. (You'll mostly find that the emitter base junction has a
> relatively low breakdown voltage, which you can see on the trace.)

For telling the collector from the emitter I use the wet finger check.

Once the base is located, I hook up the transistor to a multi meter
in Ohm mode, between the two other pins, and then apply a wet finger
between the (open) base and one of the other pins. With the finger
between base and collector, the transistor starts to conduct. If it
doesn't on either side, you may have to reverse the polarity of the
meter.

However, I haven't yet tried this with a DVM - for this I still use that
shabby analog meter from the 70s, since I know how to interpret needle
movements on this one. Analog rules...

regards & tot ziens
Christian