Remember these germanium
transistors in those days, the experimental ones that we were building in
the laboratory, were put in a little vial, a tiny test tube filled with
silicone oil to stabilize the surface.
Then it was sealed with a wax seal on the input where the wires came
into the transistor. The wax seal
was just to stabilize the wires.
So, we were experimenting with devices that were built that way, and
I guess a collector lead had broken off, and in a place we couldn’t see
So, at this point, with the
collector lead broken, then the two remaining ohmic contacts, along with
the remaining emitter lead, start to look like a unijunction
transistor. Is that right?
That’s how we got the name,
“double base diode”. When you
measure the dc characteristics of the input, when you tie the two bases
together, it was just like a diode, but when you put a field across the two
base contacts, this thing oscillated, and it was oscillating with the
parasitic capacitance of our instrumentation on the input side.
So, we were quickly then able to
determine that we had a device that was very different from what we
expected, and it was a serendipity effect because the collector contact had
opened up quite unexpectedly – as far as I can recall, that was how the
unijunction transistor was discovered.