In article , Roy Lewallen
writes:

Neon bulbs are curious critters. As you say, they have hysteresis -- a
higher strike voltage than sustaining voltage. The company I worked for
once used them as low current regulators here and there, as well as for
static protection, so they bought or selected them to various
specifications for strike and sustaining voltages.

Tektronix. :-) I'm thoroughly familiar with the 53n and 54n Tek scopes
and their "seriesed" power supplies. A rather good design concept in
my later opinion. Used to calibrate them at Ramo-Wooldridge Standards
Lab 1959-1961.

According to the parts descriptions they were controlled-characteristic
miniature neon pilot bulbs. That worked out rather well since I only had
one problem among about 300 or so scopes at R-W...and that was due
to the error amplifier (tube circuit), not the voltage reference of the
neon.

Much smaller than the common "high grade" VR tube, a 5651.


The bulbs were commonly used as pilot lamps, but not when the supply was
DC. (This lesson was learned the hard way, judging by company documents
and app notes.) Depending on the supply impedance, the pilot bulb could
become a relaxation oscillator, interfering with sensitive circuitry.

Heh, Tektronix and several other manufacturers of the 1950-1960 period.

General Electric had that problem in one piece of broadcast TV thing.
Encountered that at WREX-TV in 1956, where it was messing about
with the local color sub-carrier generator.

I came in just as their day was ending.

I'm glad those are nearly gone. Neons are a nice AC pilot bulb or night
light where the minor heat and supply current is not a problem.

Today is a whole different ballgame with logic supply voltage dropping
to 3.3 VDC and rail supplies for op-amps down to 1.5 VDC. LEDs are
now cheap, take less power, and have different colors. Neon lamps are
rather fixed at orange.

ESD built into many MOS ICs makes it much easier on designers and
users and repair folks. Gotta love it now! :-)

Len Anderson
retired (from regular hours) electronic engineer person