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 Post subject: Glowing tubes
PostPosted: 13 Dec 2019, 01:45 
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Joined: 13 Dec 2019, 01:15
Posts: 2
I realize this is somewhat outside the audio focus of this forum but Im not sure where else to turn. I would like to build a small display of a glowing vacuum tube. I have seen people build LED nightlights with the LED's jammed somewhere in the bottom of various tubes but Im not digging that. I have powered up various tube heaters and gotten a faint red-orange glow from the heater, which is cool, but I'm wanting more. I recently came across some images, likely digitally modified but still impressive with some amazing blue glow. here is the link. https://hipwallpaper.com/view/qdaP7r Anyway, I don't suppose powering the heater of say a 6N3C would cause that blue glow, or if there would be a way to power said tube economically in order to get that effect but I thought I would ask here with the wealth of knowledge you all have. Thank you in advance and please forgive the noobness if this doesn't belong here.


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 Post subject: Re: Glowing tubes
PostPosted: 16 Dec 2019, 04:00 
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Joined: 09 Oct 2012, 19:43
Posts: 357
Location: Vancouver Canada
That pic looks like time-laps photo. There are power tubes which have neon or/and argon gas in the tube. You can make the gas glow by applying a high voltage but low current supply to various pins. Depending on the architecture of the tube different tubes will glow differently inside. There are also tubes purposely full of argon gas. They were used as voltage regulators. Try 0A3 and the like. For a power supply look for HV ccts made using 555 timer and voltage multiplier. Or some of the ccts for driving 3' or 4' of neon used and sold as lights for the underside of a car etc.

This should point you in the right direction. Let us know how you do.
Laurie


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 Post subject: Re: Glowing tubes
PostPosted: 16 Dec 2019, 15:05 
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Joined: 13 Dec 2019, 01:15
Posts: 2
Laurie54, thank you very much for the info. Im feeling like I have a much better understanding of what I need and need to do. Is this what you were thinking would be a decent power supply for my project? https://www.amazon.com/Brand-Supply-Ele ... HJ1ZQ&th=1

I'm not sur what you mean by ccts and what a 555 timer and voltage multiplier is. Thanks again for the help...


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 Post subject: Re: Glowing tubes
PostPosted: 16 Dec 2019, 21:16 
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Joined: 04 Jun 2008, 20:59
Posts: 4189
Location: Arizona, USA
Hi, So far so good. Any usual tube will glow red/orange because of the heaters. Lots of diyers are putting a blue LED in the socket under the tube to make it glow blue. To actually have some large power tubes to glow blue...because of gas inside them you will need a high voltage supply. I don't believe I would do that just for looks. The LED is simpler and can be made to run off the heater voltage. Pretty much all you would need is a series resistor and possibly a second LED or diode to prevent the LED from seeing too much reverse voltage. If you actually want to power a tube with high voltage the thing you picked is not suitable as the voltage is way excessive. A similar power supply designed for either cold cathode florescent tubes (they are really small) or one for "nixie" tubes would be much better. Also as noted the vintage regulator tubes will glow in various colors (depends on the actual type used) but will require a high voltage source and at least a series resistor to keep the current flow through it at a safe level. Such tubes do not need heater power and they operate just like neon bulbs. I don't recall any that are blue...but it is possible.

Good listening
Bruce

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 Post subject: Re: Glowing tubes
PostPosted: 17 Dec 2019, 01:46 
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Joined: 13 Jan 2018, 21:33
Posts: 312
Location: australia
The Shuguang 300b tubes in my amp glow faintly blue. You can only see it if you turn off the lights though. Strangely one tube glows first almost immediately after switch on, the other some minutes after. I recall reading somewhere that the colour is due to fluorescence of a cobalt coating but can't be sure of that.

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 Post subject: Re: Glowing tubes
PostPosted: 18 Dec 2019, 03:52 
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Joined: 09 Oct 2012, 19:43
Posts: 357
Location: Vancouver Canada
Hi Sameguy. From your explanation you pointed to wanting more than just the red/orange glow of the
filament tubes. And I agree the LED under the tube look is used way too much. What I understood you
wanted was a tube that would glow blue inside and maybe could have the orange heaters glow as well
but would not necessarily be a working amp but more of a night-light / conversation piece. If so what
you need is 2 items.

1- A safe low current but high voltage power supply.
Find the power supply first or build it. This time of year cruse the Ridio shack's $1.00 bin for one of those
globe lights that emits sparks from a center ball inside the globe. Perfect power supply.

2- A vacuum tube, good or bad as long as the glass is not broken
Argon = blue type 0A2/0A3 Neon = orange type 6as7. Use a source where you can get cheep tubes
as you are not making an audio amp just a light. You want to make the inert gas in the tube glow. You
may need a few different tubes to try.

Woodo. If you applied a high voltage 800v+ / high freq like 28Khz / very low current source to the pins of your 300B's the entire
glass envelope would glow just like a neon pilot lamp only well,,,,,,,bigger and pale blue. Argon needs a higher voltage
if lacking in mercury vapor to lower the resistance of the gas as one in florescent light tubes. Most amps do not have
tubes that glow until the tubes are getting higher voltages and higher voltage drops across the plate to cathode.

I have done this myself and it is a very nice effect but was paying pennies per tube so I could experiment.
The ones I made were all orange glowing as they contained neon gas. It is mesmerizing to watch the orange
gas glow. Placing a fingertip to the glass makes it glow more under your finger. If the tubes gas happened to
be argon it would glow blue. My experimenting was with color / effect for film / movies etc and not for an audio
amp at all. But a lot of fun and produced some very unique lamps.

Here is a good source of safe dependable reasonable power supplies for the experimentor.
https://www.amazing1.com/neon-transformers-12v.html

The smallest of these SWPS would make a few tubes glow together. Your suggestion of transformer would power the tubes
BUT !!!
It is way OVERKILL and is a possibly LETHAL supply to be experimenting with. 1/2 that voltage and 1/4 that current rating would be more than enough for driving many tubes.
Have a look. Have fun. Experiment. BUT DO IT SAFELY ABOVE ALL.


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 Post subject: Re: Glowing tubes
PostPosted: 18 Dec 2019, 06:20 
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Joined: 13 Jan 2018, 21:33
Posts: 312
Location: australia
Thanks Laurie good to know it’s argon causing the glow. It’s nice sitting in the dark and watching the ghostly glow while beautiful music is flowing.

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John


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 Post subject: Re: Glowing tubes
PostPosted: 18 Dec 2019, 15:35 
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Joined: 03 Jul 2019, 10:36
Posts: 7
You could try "Magic Eye" type tubes, they were used as a tuning indicators in valve radios,
I think they were usually green when glowing.


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 Post subject: Re: Glowing tubes
PostPosted: 18 Dec 2019, 21:40 
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Joined: 09 Oct 2012, 19:43
Posts: 357
Location: Vancouver Canada
Woodo "" I recall reading somewhere that the color is due to fluorescence of a cobalt coating but can't be sure of that.""
Yes it is this as well. The fluorescence of a cobalt coating will also cause glowing although slight in nature. The glow
is week. VR tubes like the 0A2 etc are full of argon gas.
I would get a safe HV pwr sply first. I say safe as it is inevitable one will get zapped sooner or later working with these
sply's but the odd shock keeps us attentive and alert while we work with such things. I say first because once you have the supply
any and every tube one can get ones hands on can be tried for gas with the sply. Tubes on ebay can be bought rather cheeply.


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