"Ian Thompson-Bell" wrote
Don Pearce wrote:
Very nearly - it was the collector back then. Were they the type with
clear gel filling that you could use as phototransistors if you
scraped the paint off?

IIRC types like the AC128 had metal cans. I think it was the good old OC71 that you could scrape the paint off to make a
photo-transitor - that is until they started filling them with opaque gunk.

That's right. AC128 were metal-canned; and the can was rather long
compared to a metal-canned BC109, for example. AC127 was the NPN
equivalent, but I don't think I ever used that. It also in later
years struct me as a bit off that the book used exclusively AC128,
which is PNP, when NPN transistors seem to be far more commonly-
used than PNP. Because PNP was the first transistor type I was
exposed to, I kinda ended up thinking that was "the normal way",
and NPN seemed odd at first.

I did have some (kinda) OC71 transistors, but they were more
modern-looking than the originals; they were called OCP71, I
think, and were blue plastic at the bottom, and then they had
the glass bulb filled with gel. They were about the same size as
AC128, and also had long bendy wires on them.

Martin
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