When they are used in that manner they are usually painted black.
Voltmeters have not always been affordable for me. I had an "extinction
voltmeter" constructed with a pot and an Ne-2. It was also useful as an
RF probe. You set the pot to a value just below ignition and used the
lamp as a probe. When it was driven by RF it would have a purplish glow.
The raw tube could be moved up and down a twinlead line to find the
QST once had a frequency counter used TTL logic and Ne2's for
indicators. I built one and even got it running. It is tucked away
somewhere. There are at least a hundred Ne-2's in it! The real fly in
the ointment is that the Ne-2's were also great noise generators...
I have left behind quite a few Ne-2's in AC wall switches. A 100k
resistor in series with the Ne-2 and across the switch contacts was very
handy. Leave the top plate mounting screw out so the lamp was visible.
When the switch was off the Ne-2 was indicating or the load was missing.
Handy when you could not see if the outside light had been turned
on|off. Since it was on when the load was off, it was easy to find in a
On 7/6/2012 10:01 PM, rchadwic wrote:
> Interesting thread. And another point about neon bulbs.... If you are using
> them, remember that the ionization point is light sensitive.
> I spent 3 weeks troubleshooting a strobe light that used a NE2 relaxation
> oscillator trigger; it intermittently would not work, and no logical
> troubleshooting got me anywhere. Finally the penny dropped and I noticed
> that it was not working when the package was closed, but worked fine in
> ambient light. I recalled from about 40 years ago that these bulbs were
> light sensitive....
> Watch out.
> Bob Chadwick W1MTX
> Palm Bay, FL
> PICList Lurker
John Ferrell W8CCW
"During times of universal deceit,
Telling the TRUTH becomes a revolutionary act"