wiring a tube just for light

[Dimitree]

hello
I have some spares tubes (EL84) that I don't use, I want to use one of them as "light source", so I just need it to light up, and nothing else.
I tried to put 12V DC on the heaters (+ on pin 4, - on pin 5) but it didn't work.
What am I doing wrong?

thanks and sorry for my ignorance about tubes

[digi2t]

I think that you need 6.3 volts AC. I'm not sure if the filaments can withstand 12 vdc.

[antonis]

What am I doing wrong?

Using tubes for light...

[Dimitree]

I think that you need 6.3 volts AC. I'm not sure if the filaments can withstand 12 vdc.

I did that because I've read somewhere that you can even use DC, from a 12V battery for example.
but I may be wrong, hence the topic

[Vitrolin]

6,3v AC or DC isnt important for the heather voltage.

[Ben Lyman]

Just curious. Why? Stage prop? Mood lighting?

[digi2t]

I would get one of these...



and stick an LED in the center hole. You can pick your color, and adjust your intensity. EL84 has the advantage (in this case) of not having a base around the pins, so the LED will light that sucker right up.

[Dimitree]

I only would like to know if I can provide 12V DC to the heaters of the EL84, and if yes, how should I wire them, and if that would make the tube glow.
simply that..

[rutabaga bob]

The data sheet I just looked at says 6.3. volts for heater.  Wire pin 4 to one side of the 6.3, and pin 5 to the other (one is positive, one negative).

If you've got spares you don't use, PM me if you're in the U.S.

[Dimitree]

I give up..

[rutabaga bob]

Don't give up...I am wondering if, when you wired the tube @ 12v, you didn't burn out the heater wire.  It's not meant to have 12v on the heater.  If you have an ohmmeter, put one test lead on pin 4 and the other on pin 5 and see if you get a reading.  If the meter shows no resistance, the tube is shot. 

[stallik]

Most of my 12au/X tubes have elements that are at least partially obscured. Even when the tube is powered up and working correctly, you only see a dim glow from certain angles. They certainly don't glow like a 6v6 or el34 can

[Kipper4]

If the tube is shot stick an orange led behind it. Instant glowing tube.

[Lothric]

if You want to use it as a "decoy" light it up with LED underneath or something.... otherwise prepare 6VDC or AC, You will need around 800mA for one tube  LOL ! 

[davent]

If you have two el84's you can put the heaters in series and power them with your 12v but i wouldn't try 12v on a single el84 or multiples hooked up in parallel.

Datasheet will say 6.3v plus/minus 10%. With no other power applied to the tube no idea whether the 12v would cause damage  but i wouldn't take the chance with good tubes that could later be put into service.

dave

[PRR]

12V on a 6V heater WILL "cause damage".

Put 240V on a 120V incandescent light bulb. It goes off like an old fashioned camera flash, and dies permanently. 120V on 6V rated, same thing.

My calculation says a tube heater's expected life at double voltage may be as much as one hour. But that's a violent impact and heater flaws that make no trouble at design voltage may blow instantly at this abuse.

Yes you can run "tubes" on a 12V battery. 12 Volt tubes!! (12AX7 can be wired for 12V use.) Or two 6V tubes series. That was often done in the last days of tube car radios. You do have to get the voltage right.

[duck_arse]

Dimitree - wire them for heat, not for light. one question - what sort of power supply did you use for the 12V, what was its current capacity?

[Lothric]

For 2x ecc83 you need around 700mA,for 2x el84 prepare 1.6A

Wysłane z mojego MotoE2(4G-LTE) przy użyciu Tapatalka

[davent]

For 2x ecc83 you need around 700mA,for 2x el84 prepare 1.6A

Wysłane z mojego MotoE2(4G-LTE) przy użyciu Tapatalka

For two leds, a mA or two.

dave

[Lothric]

I gave the current for the set of 2 valves. I know you can use lower current for 12ax7 if you go with 12v

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