Mmm... some ballast kind of thing, or even a very strange gas tube if you say it has a plate... however, from the photo, no signs of getter or plates.
Have you tried to light it up? Maybe firstly measure DC resistance of the filament, just to make a rought guess on what voltage this is supposed to run.
Have you tried to light it up? Maybe firstly measure DC resistance of the filament, just to make a rought guess on what voltage this is supposed to run.
I think that it is a barreter, can't even remember if that is how they are spelt.
I used to be a technician in British Telecom many moons ago, and when I was an apprentice we used to have to change the things.
They were used as current limiters in subs circuits. They are basically light bulbs.
hope that helps.
bill
I used to be a technician in British Telecom many moons ago, and when I was an apprentice we used to have to change the things.
They were used as current limiters in subs circuits. They are basically light bulbs.
hope that helps.
bill
It looks like a barreter to me too. I have an AC/DC Phillips radio that was wired by a madman that uses one. It performs current limiting for the series filament circuit, necessary because of the wide range of voltages the thing may get plugged into.
It has no transformer you know, a live chassis. They don't do things like that anymore...
It has no transformer you know, a live chassis. They don't do things like that anymore...
I think it looks like a barretter (two "t"s). As previously mentioned in this thread, they were used in telegraph circuits as short-circuit protection and glowed like lightbulbs when driven into a short-circuit. The difference between them and a lightbulb is that instead of the bulb being evacuated, it's filled with nitrogen. The other use of their non-linear resistance was in series heater chains to keep the current constant.
I have a few flimsier versions and hadn't previously seen such a beefy example.
I have a few flimsier versions and hadn't previously seen such a beefy example.
Here in the United States, ballast tubes (barretters) are filled with either hydrogen or helium and are used as current and voltage regulators. They are still available from Amperite. Light bulbs here are generally filled with a noble gas under low pressure, so the main difference between the two is that the ballast tube generally has a higher resistance filiment and doesn't glow as brightly.
John
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