"BillW50" wrote in message
. com...
In ,
Arfa Daily typed on Fri, 28 Mar 2008 12:52:58 GMT:
[...]
As for a transistor radio that uses PNP transistors, I haven't seen
one that uses transistors at all for many years, let alone PNP ones,
so I think you might be struggling to fit that into my "modern"
category, also.

Well Arfa... they still use transistors (both NPN and PNP types) in modern
equipment. The reason you don't see them anymore is do to the magic of
minturization. But they are still there, just neatly packaged into what is
known today as the intergrated circuit (IC chip).

--
Bill
And I though I was pedantic !! Yes, of course ICs contain transistors, and
yes, I would accept that some of them may be PNP types, depending on block
function within the IC, but I don't think, with the best will in the world,
that this is the level of transistor existence that William was referring to
with his "transistor radio using PNP transistors" scenario. In any event, in
the case of an IC taking a single polarity rail, it is irrelevant whether
the transistors inside are NPN or PNP or FETs or whatever. PNP transistors
are just used 'upside down', as are discrete PNP transistors when used in
any piece of single polarity rail equipment. The ground is still (typically
for //modern// equipment) the "-" side of the power supply / battery.

Anyway, this is getting out of hand. The OP aked a simple question, and I
gave a simple answer. This afternoon, I was in a friend's computer repair
shop. Bear in mind that he deals with monitors of all types and makes on a
daily basis. I asked him how he would go about determining the polarity of
such a monitor, and he said that he would stick one side of his ohm meter on
one of the D connector locking screws, and the other on each pin of the DC
connector. When he found the pin that read short to the connector locking
screw, it was his contention that he would have identified the "-" side of
the power supply. So that's pretty much exactly what I said. He also frowned
and shook his head, and said that he couldn't remember how many years it had
been since he had seen a DC connector that had the pin as the "-".

Which is also pretty much what I said ...

Arfa