20 Apr
2005
20 Apr
'05
8:11 p.m.
Probably the _last_ versions of multifunction vacuum
tubes were the
'Compactron' tubes, specifically designed multi-element tubes used in
the 60's and 70's in sets sets designed to use with fewer tubes, i.e.
portable tube-type televisions. Compactrons were in an envelope similar
in shape to the common 7 and 9 pin mini tubes, but bigger with (if I
recall correctly) 12 pins.
Certainly, multifunction tubes were around - the first ones were the dual
diodes and rectifiers of the 1920s, then later twin triodes, extra diodes,
and yes, to the ultimate Compactrons.
Integrating the functions, like in the Loewe tubes, never caught on. In
the US, a few directly coupled triodes were produced (6N6G being the most
common), and some of the eye tubes had a built in triode as a driver, but
for the most part, each function was pinned out individually. The most
advanced integrated tube was probably the VT-158 Zahl tube - a 600 MHz
pulse oscillator in a bulb. It was a dead end.
On a side note, there are some really bizarre miniature tubes made for the
electronic organ industry back in the 1950s - quad triodes (with shared
grids), dual grid triodes, and so forth. These were specifically made for
tone dividers. I suppose they could have been interesting computer tubes,
but none were computer rated. They tend to be damn hard to find these
days.
William Donzelli
aw288 at osfn.org