Michael Black wrote:


Of course, towards the end of the life of tubes, one could get some that
ran off 12v, intended for use in car radios. Not so useful now since they
were produced in a limited time span as transistors were taking over, so
quantity is relatively limited.

Even rarer were tubes that drew almost no current. They used "cold cathodes"
so they did not need expensive (in terms of current and heat dissipation)
filaments and had low plate voltages.

They came out when transistors where just starting out, but rise of
transisitors was so rapid and transistors were so cheap in comparison, that
it was simpler and cheaper to build a 7 or 12 transistor radio than a 5 tube
cold cathode one.

They showed some promise in the missle and space exploration systems of the
time, because transistors could not stand the temperature extremes or
cosmic radiation they would be exposed to. That also did not last long,
as improved "space grade" transistors came out.

What really killed them was NASA's adoption of the new integrated circuits
(which actually pre-date the "space race").

Geoff.


--
Geoffrey S. Mendelson, N3OWJ/4X1GM
My high blood pressure medicine reduces my midichlorian count. :-(