3 lead neon lamp?

[JohnR66]

Picture the typical neon indicator lamp, such as the NE-2. Now picture it
with three electrodes in a row and three wire leads. I saw a picture of one,
but no idea of what it is for. Best I can come up with is a situation where
two separate sources drive the lamp or perhaps a dual brightness lamp? Any
ideas on this thing?
John

 

[Andrew Gabriel]

Picture the typical neon indicator lamp, such as the NE-2. Now picture it
with three electrodes in a row and three wire leads. I saw a picture of one,
but no idea of what it is for. Best I can come up with is a situation where
two separate sources drive the lamp or perhaps a dual brightness lamp? Any
ideas on this thing?

I've no idea, but I would guess the device is designed to exploit
the electrical characteristics of a neon discharge lamp, rather
than the lighting effect. For example, exceeding the striking
voltage (~90V) across any two of the electrodes would probably
result in the lamp switching into voltage stabalising (~60V)
across all 3 electrodes. An application might use this where
one of the electrodes is used as a trigger.

One other thought would be as a power indicator lamp in a 3-phase
3-wire (delta) system.

 

[Clive Mitchell]

Picture the typical neon indicator lamp, such as the NE-2. Now picture it
with three electrodes in a row and three wire leads. I saw a picture of one,
but no idea of what it is for. Best I can come up with is a situation where
two separate sources drive the lamp or perhaps a dual brightness lamp? Any
ideas on this thing?
John

Could it be a sort of flip-flop component in a high voltage oscillator
circuit?

 

[Bart Z. Lederman]

I think it's most likely a gas discharge spike (surge) surpressor.

There are a number of types of these devices made. The reason
for the three leads is that (usually) the two outer leads are
connected to the two power lines, the center one is connected
to ground. I believe the theory is that if a spike causes
a discharge on one half of the circuit, the other half of the
circuit is more likely to conduct as well. They are also used
on things like telephone lines, where if one side of the line
has a spike you want the other side to conduct to ground as well
at the same time.

Bart.

 

[JohnR66]

I think it's most likely a gas discharge spike (surge) surpressor.

There are a number of types of these devices made. The reason
for the three leads is that (usually) the two outer leads are
connected to the two power lines, the center one is connected
to ground. I believe the theory is that if a spike causes
a discharge on one half of the circuit, the other half of the
circuit is more likely to conduct as well. They are also used
on things like telephone lines, where if one side of the line
has a spike you want the other side to conduct to ground as well
at the same time.

Bart.

Could be part of an oscillator or 3 phase indicator. I doubt it is a surge
device, the thin wire leads don't seem up to that.
John