OT: Do any "long-life" magic eye tubes exist ?

[gregebert]

I did some research and found that common magic eye tubes, such as the 6E5, have a pretty sort lifetime, maybe 1000-2000 hours.

Have any of you found round, end-view magic eye tubes with a substantially longer lifetime ?

I'm building a new clock with green neon bulbs, and a functioning magic-eye tube for the center of the clockface would be perfect.

I keep my clocks illuminated 24/7, hence the need for a longer lifetime (eg, over 20K hours)

I may end up making a fake magic eye tube with neon bulbs, but it wont have the smoothness or the nice color of the real thing.

[Instrument Resources of America]

My understanding is that all of the GREEN eye tubes like the 6E5, 6U5, 6G5, 6T5 and similar, used a mineral known as willemite, to create the green glow. The willemite when bombarded by electrons gave off the green glow. As it aged the willemite became less and less active. So my guess would be that NO, you will not find any 'long lived' 20k plus hour eye tubes.  Ira.

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[Dekatron42]

I spoke to a vacuum tube designer a few months ago, well into his nineties now, who told me the same thing. He told me that apart from the glow fading due to the material used to produce the glow many tubes had a problem with the cathode not emitting electrons as designed and expected which also led to less glow after some time. He told me that the two biggest areas in tube design was in cathode design and grid design, all other areas he regarded as simple! So I too think that it will be hard to find any long life eye tubes out there.

/Martin

[Instrument Resources of America]

You MAY be able to obtain a one inch CRT and drive the deflection plates with appropriate signals and 'simulate' and eye tube.  Ira.

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[gregebert]

>You MAY be able to obtain a one inch CRT and drive the deflection plates with appropriate signals and 'simulate' and eye tube.  Ira.

Interesting idea, but it would probably make the clock-case too deep to accommodate the CRT.

Even the 6E5 I was hoping to use was pushing the limit.

[John Rehwinkel]

On Thursday, 12 March 2015 18:30:38 UTC+1, gregebert wrote:

I did some research and found that common magic eye tubes, such as the 6E5, have a pretty sort lifetime, maybe 1000-2000 hours.

Have any of you found round, end-view magic eye tubes with a substantially longer lifetime ?

There are ways to increase the lifetime of these tubes.  Normally they're operated at lowish voltage and high current, which rapidly damages the outer phosphor layer.  However,

they can be operated at higher voltage and lower current, leading to greater electron penetration and greater phosphor life.

I spoke to a vacuum tube designer a few months ago, well into his nineties now, who told me the same thing. He told me that apart from the glow fading due to the material used to produce the glow many tubes had a problem with the cathode not emitting electrons as designed and expected which also led to less glow after some time.

Running at lower current would also likely extend cathode life.  Note that most eye tubes have a space charge grid around the cathode, which both limits cathode current and

gives some interesting striations to the resulting glow.  It would be handy if this grid were brought out to a separate terminal for greater control on emission.  In most tubes,

it's simply connected to the cathode, giving essentially zero grid bias.

You MAY be able to obtain a one inch CRT and drive the deflection plates with appropriate signals and 'simulate' and eye tube.

This is an interesting idea.  Most of those one inch CRTs use an ordinary P1 phosphor (Mn-activated zinc silicate), which is a subtle variant on the willemite phosphor (Mn2+-activated zinc silicate)

used in eye tubes.  I'm guessing the CRTs have longer life because of the aforementioned higher voltage and lower current.  Some CRTs use an aluminized screen to increase brightness and reduce ion

damage, but I don't think any one inch units do.  There are small CRTs with other phosphors, but they might not give the color you're looking for.

Similarly, there are some eye tubes (generally those with the phosphor deposited on the inside of the glass like 6HU6) which probably last longer, but they too are generally a different

(more blue) color.

Another possibility is a vacuum fluorescent display.  These use a different cathode technology capable of extremely long life, as well as different phosphors (zinc oxides and sulfides) optimized for

long life at low voltage and modified for increased conductivity.  However, they too are more blue than most eye tubes.

Once upon a time, there were very high brightness green fluorescent tubes used for copiers and underlights for escalators.  These had a double layer, of white paint and

then green phosphor, along with a linear "window" where no phosphor was applied.  These are capable of very long life, high brightness, and they're brilliant green.  However,

they're large, power hungry, and hard to obtain these days.  However, there are small colored phosphor CFLs that give nice pure light.  One of these might serve.

There are also some Russian bulbs that work like the green NE-2 bulbs, but they're larger, about 1cm in diameter.  Don't know about their lifetime.

- John

[Dan Harboe Burer]

I have another (crazy? wild?) suggestion:

 

Go mechanical.

 

See my attached picture. You should be able to simulate a magic eye with a couple of counter-rotating (bevel) gears with oval slots cut in them, a light source and some matt plastic or glass, behind them and a small (stepper?) motor to run it. It might even be possible to make this quite compact – in theory at least

I would try to find nylon gears – they are easiest to cut in..but with access to “real” machinery it could look quite cool with brass gears.. a “steampunk” magic eye?

 

Sorry for the primitive drawing. I just threw it together on my desk .. let me know if you want a more accurate description..

 

Regards

Dan

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[David Forbes]

On 3/12/2015 11:25 AM, Instrument Resources of America wrote:
> You MAY be able to obtain a one inch CRT and drive the deflection plates with
> appropriate signals and 'simulate' and eye tube. Ira.
>

I have a bunch of 7/8" 1DP1 and 1-1/4" 1EP1 CRTs if you need some. Also
transformers to power them.

[Tidak Ada]

An easier way is used in the magic eye of the old radio my parents used in my early youth:

It was magneto-mechanical and functioned at the way of an old galvanometer. The pointer was  a diabolo shaped piece of shading (magnetized?) material. At one side there was an ordinary scale bulb and at the other side a greenish, frosted disc of glass with a black dot in the centre.  The shade of the diabolo projected to the glass resembled the shade of an EM34. It could be a narrow line at maximum and a diabolo at zero.

 

There must be a drawing , but I cannot find it at the moment.

 

eric

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[Tidak Ada]

The only SQ tuning indicator I can find is a E82M/5624 You can find it at
Åke Holm's site [ http://www.sm5cbw.se/tubes/htm/em82.htm ]
But that is a kind of magic-bar type.

eric

-----Original Message-----
From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On
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Sent: donderdag 12 maart 2015 20:13
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[gregebert]

Thanks everyone for the responses.

I purchased two 6AF6G tubes, and because of the way my big clock was designed, I believe I can get fine-grained control of the magic-eye tube from my NMOS drivers without changing the PCB (just a few component and cabling changes).

I will attempt to make a replacement module with green neon bulbs that I can swap-out with the 6AF6G. They wont be pin-compatible with eachother, but at the connector where they plug into my clock PCB, they will be interchangeable. And since I use an FPGA for the clock logic, it's easy to support both by flipping a DIP switch.

[Billy Watson]

here it is, on this web site,   ~+~    http://www.magiceyetubes.com    ~+~   
left side of page index        under eye relatives       " The shadow graph "

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[Billy Watson]

here is another with spinning LED's      Building A Mechanical Magic Eye

[JohnK]

How about the very miniature display tubes in [old] vid cam eyepieces then?

 

John K

Australia

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[Tidak Ada]

Trouble will be the magnetic deflection. An 1" electrostatic tube will be easier to manage. You can avoid the cabinet depth by placing the tube parallel to the front and use a mirror at 45° to get the view in the right plane (just like old TV-sets). However, be aware the view will be in a mirrored order. This you can solve easily in your electronics....

 

There is also a 3/4" electro statically deflected CRT: R2163 from  NU (National Union)

 

eric

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From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of JohnK
Sent: vrijdag 13 maart 2015 8:20
To: neoni...@googlegroups.com

Subject: Re: [neonixie-l] Re: OT: Do any "long-life" magic eye tubes exist ?

How about the very miniature display tubes in [old] vid cam eyepieces then?

 

John K

Australia

----- Original Message -----

From: gregebert

To: neoni...@googlegroups.com

Sent: Friday, March 13, 2015 5:12 AM

Subject: Re: [neonixie-l] Re: OT: Do any "long-life" magic eye tubes exist ?

>You MAY be able to obtain a one inch CRT and drive the deflection plates with appropriate signals and 'simulate' and eye tube.  Ira.

Interesting idea, but it would probably make the clock-case too deep to accommodate the CRT.

Even the 6E5 I was hoping to use was pushing the limit.

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[Tidak Ada]

Not exactly what I described, but the principle is the same.

 

I made a Corel drawing from what you got to see

 

eric

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Sent: vrijdag 13 maart 2015 0:50

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[John Rehwinkel]

How about the very miniature display tubes in [old] vid cam eyepieces then?

Those are common and cheap (I have a box of 'em), but they're P4 (whitish) phosphor.  The 1DP1 and 1EP1 CRTs that David mentioned have a green P1 phosphor

which would be a much better color match.  Better yet, they're electrostatic focus and deflection, which is easier to work with than the magnetic deflection 40CB4

viewfinder types.

- John

[Yuriy Ovchinnikov]

I have 6E5S. Need?

четверг, 12 марта 2015 г., 20:30:38 UTC+3 пользователь gregebert написал:

[Instrument Resources of America]

The CRT's I had in mind are all actually shorter than the 6E5 eye tube,    Ira.

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[Tidak Ada]

Here a photo of the unit I deicribed before. Sadly the lamp, the eye screen nad the housing are removed.

The shade triangle (not a diabolo) is clearly visible. Below that there is the electromagnet that actuates the vane.

 

Here a translation of the tekst that accompained the photo:

 

The electromagnetic movement exists of an lamp holder (lower left), a coil (1200 Ohms), a moving magnet with a triangular vane and a flat bias magnet.

The light falls via a square opening in the backwall of the housing (not visible) on the vane, that covers the light more or less that falls on the green frosted glass plane, that forms the eye.

With the screw at the top, one can compensate for the bearing play and the screw at the bottom sets teh zero position.

 

This unit was used in the Waldorp 116. Waldorp was a Dutch pre-war radio constructor in The Hague...

 

eric

 

 

 

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Subject: Re: [neonixie-l] Re: OT: Do any "long-life" magic eye tubes exist ?

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