"William Sommerwerck" wrote in message
...
It's a PNP transistor. The emitter has the highest voltage, so it is
something opening in the collector path to ground. When it opens, the
base voltage rises because the transistor is no longer biased properly.

I haven't got a copy of the circuit to hand, but I'm not sure that I
understand what you're saying. A PNP circuit is just the same as an NPN
circuit, but with the battery upside down. Ground is ground and bias is
bias, applied between the base and emitter. Doesn't matter whether it's a
PNP or an NPN transistor, the ground reference is just the opposite pole
of
the battery. The emitter having the "highest voltage" is basically an
arbitrary term as that voltage could be 'higher' in a positive or
negative
direction, depending on where you are taking to be your measurement
reference. Things get a little more complicated to get your head around,
where the circuit is powered the 'conventional' way up, but the
transistors
are in upside down. Maybe that's what you're saying here ?

I was going to demur, too.

In a junction transistor, the EB junction is forward-biased, the BC
junction
reverse-biased. The EB junction can be correctly biased even if the
collector is dangling. I don't see how opening the collector's path to its
intended voltage source would alter the base voltage.

Agreed

Arfa