Those must be in the same family as a couple of things I
remember from years past. Sixties-vintage elevators or lifts had
these gas discharge tubes for each button. The tubes ran at slightly
below breakdown voltage and fired when one touched a square pannel in
the center of a boundary that lit up when the tube activated.
They also lit up if the air got very humid and the elevator
would start randomly going from floor to floor taking ghost
passengers.
I also remember a foreign language lab made by Rheme Califone
in which there was a light pannel for signaling the instructor. The
student pushed a momentary-on button on his or her console and a neon
lamp lit up in the control room and stayed on until the teacher got
tired of looking at it and reset it.
The power supply for the lab had a solid-state regulated power
supply for the audio boards in the tape decks and then there was this
7-pin tube sticking up out of the chassis.
The tube turned out to be an OB2 which is a 105-volt gas
discharge regulator. It kept a voltage on the signal lamps just below
breakdown. I am not sure what the "teacher" call buttons actually
did, but they momentarily increased the lamp voltage and made them
fire.
I used to repair one of those systems as late as the mid
eighties, but they didn't use the neon call lights for anything so I
never seriously studied what pushed the lamps over breakdown. It
could be that those were 3-terminal neons that had a trigger lead kind
of like a strobe.
I do know that one day, a diode burned out on the low-voltage
supply and ruined the transformer, smoking up the whole room.
By that time, it was the mid eighties and that system hadn't
been made for many years. We were able to buy a replacement
transformer for the audio boards but that flame-out was the death of
the call light system.
Martin McCormick WB5AGZ Stillwater, OK
OSU Information Technology Division Network Operations Group
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Author: Martin McCormick
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Fat City Network Services -- 858-538-5051 http://www.fatcity.com
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