Filaments glow. You will need 20 volts, 6 amps to light two tubes (3 amps per tube, connected in parallel). The tubes will slowly wear out, but I guess you don't care about that.
An externally hosted image should be here but it was not working when we last tested it.
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Oh thanks! they are already worn out as my friend said they have passed 4000hourse of working and he doesn't like their sound anymore. he wanted to throw them away but I took them. he said they will shine relatively steady for a long period of time as long as the wire in there is fine.
so the filament shines. the plates also becomes red when the amplifier is on. right?
I make nightlights by sticking an amber LED up in the tail end of old tubes that test bad.
I have made quite a few of them and everybody seems to like them.
This way you don't have high temperature just to get them to glow.
The trick is to find an amber LED that is the same shade of orange as the heater glow.
I have made quite a few of them and everybody seems to like them.
This way you don't have high temperature just to get them to glow.
The trick is to find an amber LED that is the same shade of orange as the heater glow.
Looks nice. Do you have any photo??
I have one damaged GM70.
Unfortunately GM70 have a aluminium base.
They are a standard size T1 I think or maybe 4mm or so.
The color is Amber in the 590nm range.
THIS one would work fine.
On the Octal sockets I will grab the locator pin and snap it off being careful not to break the tail end of the envelope that is inside it.
Even if that happens it's no biggie, you just need to shake the tube until all the bits of glass come out.
Then you can use 2 of the unused pins on the socket to solder the legs to and just point the LED through the tail end of the tube.
It is important to find an LED with a narrower angle, 30 degrees or so works well.
The color is Amber in the 590nm range.
THIS one would work fine.
On the Octal sockets I will grab the locator pin and snap it off being careful not to break the tail end of the envelope that is inside it.
Even if that happens it's no biggie, you just need to shake the tube until all the bits of glass come out.
Then you can use 2 of the unused pins on the socket to solder the legs to and just point the LED through the tail end of the tube.
It is important to find an LED with a narrower angle, 30 degrees or so works well.
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You can also make very nice night light with tube voltage regulator, you can get amber, blue, it just depends on the gas inside the regulator. The links below has an exemple that also dimms during the day time.
Voltage Regulator Tube Nightlight
Voltage Regulator Tube Nightlight
Oh thanks! they are already worn out as my friend said they have passed 4000hourse of working and he doesn't like their sound anymore. he wanted to throw them away but I took them. he said they will shine relatively steady for a long period of time as long as the wire in there is fine.
so the filament shines. the plates also becomes red when the amplifier is on. right?
No, the GM70 is not designed to run red plate.. I am running amps that use GM70. Please note that even with just filament power applied they get hot enough in short order that they can cause serious burns. Make sure they are out of reach. They aren't an efficient source of light either and with 4K hours use they won't last long unless you take precautions to limit the cold inrush current. (Use a varistor rated for operation at 3A continuous in series with each tube filament and a transformer able to provide 20Vac @ 6A (add 25% to keep the transformer cool)
As an alternative, I saw something on an amateur radio site (or email list or magazine - it's been probably 10-20 years ago and I don't recall the source) using a tube that had a burnt out filament.
A low current (maybe 1mA), high voltage (many hundreds of volts, higher than the tube was ordinarily rated for) was put between two elements such as cathode and plate (I forget if it was DC or AC, but the LOW CURRENT part is important), and with the voltage high enough the tube would glow like a neon light, similar to that "voltage regulator neon light." But it would be a curio just for show, and wouldn't give off a substantial amount of light, no more than an LED at the most.
A low current (maybe 1mA), high voltage (many hundreds of volts, higher than the tube was ordinarily rated for) was put between two elements such as cathode and plate (I forget if it was DC or AC, but the LOW CURRENT part is important), and with the voltage high enough the tube would glow like a neon light, similar to that "voltage regulator neon light." But it would be a curio just for show, and wouldn't give off a substantial amount of light, no more than an LED at the most.
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