Neon size limitations?

[B Otto]

Reading the thread on "fake gigantic nixies" got me thinking about the possibilities or REAL gigantic neon applications. Is there a practical limit on how large a neon indicator could be? Using traditional methods, would it be possible to make a neon glow lamp from say a five gallon carboy?

[Tidak Ada]

I am afraid it will be very expensive to buy the amount of neon.
Further, I think the supply voltage will need to be dangerous high in case
you want to keep the ratio of the dimensions intact and the needed current
will be high, resulting in an unpleasant power consumption.

eric

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[Dalibor Farný]

As Tidak Ada mentioned, It would be necessary to keep the anode cage /
cathodes distance the same as in small tubes to keep the breakdown
voltage the same. I dont know whether the discharge would behave the
same way when distances (and voltage) would be increased to keep the
proportions.. There will also be problem with power consumption.. Cost
of neon is absolutely no problem, if You want to fill a half cubic
meter to 25torr, that would be 20 liters of neon - $100.. The biggest
trouble will be tooling and machinery, it is not easy to make large
glass envelopes, stems and other stuff. Also a bakout oven for large
tubing would be necessary.

It is my secret target, to make as big nixie tube as possible,
hopefully I will present it here one day - I have some ideas of how to
.. I am starting from small ones, going step by step higher ;-) I may
reveal that the small scale manufacture of 50mm digits tubes is almost
ready. I wish to have more time to document the progress :-(
You can see some snapshots here: https://www.facebook.com/daliborfarnycom

Sorry for using that thread for self promotion ;-)

Dalibor

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[NeonJohn]

One could but it would be a fairly dangerous object. You'd have about
as much volume enclosing a vacuum as a large picture tube but without
the engineered safeguards against implosion. I'd be a bit nervous being
around the thing.

John

>

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[greg...@hotmail.com]

But, unlike a picture tube, you could put internal support structures within the "tube" which would make it unnecessary to have really thick glass in specific areas.

Then it becomes a matter of how you would glass-cast it and insert the cathodes. A 7-segment giant nixie would be relatively "easy" to do; trying to preserve

the individually-shaped numerals (which in my opinion is what makes nixies so beautiful in the first place) will take some careful planning.

BTW, if you have ever broken a picture tube, it's rather fascinating how thin the glass is towards the neck versus the outer ridge at the front. 

Which is why we always threw tubes on the ridge to maximize the BOOM....21FJP22's were my favorite. Breaking the neck is flat-out boring..

[Dalibor Farný]

Common nixie tube envelopes have advantage of egg-like shape, the
stress is uniformly distributed in the glass.. Picture tubes have one
side flat what makes the shape more prone to implosion.. Also proper
annealing will be important.

Good remark anyway!

Dalibor

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[Tidak Ada]

Indeed,

 

I once opened a 50 cm B/W picture tube to make a lamp of it. I carefully packed the tube in thick blankets and then filed off the exhaust nipple. About one minute of hissing and the pressure was equilibrated. No danger at all!

 

eric

---

From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of greg...@hotmail.com
Sent: maandag 28 april 2014 18:33
To: neoni...@googlegroups.com
Subject: Re: [neonixie-l] Neon size limitations?

--

[Matthew Smith]

Quoth Tidak Ada at 2014-04-29 06:13 ...

> I once opened a 50 cm B/W picture tube to make a lamp of it. I carefully
> packed the tube in thick blankets and then filed off the exhaust nipple.
> About one minute of hissing and the pressure was equilibrated. No danger
> at all!

Aha! I wanted to get the electron gun and base of a CRT, to re-mount
into a longer accelerator structure - was wondering how to break the
vacuum safely.


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[NeonJohn]

On 04/28/2014 04:47 PM, Matthew Smith wrote:
> Quoth Tidak Ada at 2014-04-29 06:13 ...
>> I once opened a 50 cm B/W picture tube to make a lamp of it. I carefully
>> packed the tube in thick blankets and then filed off the exhaust nipple.
>> About one minute of hissing and the pressure was equilibrated. No danger
>> at all!
>
> Aha! I wanted to get the electron gun and base of a CRT, to re-mount
> into a longer accelerator structure - was wondering how to break the
> vacuum safely.

That works but it pretty much destroys the evacuation port for future
use. I have the same intentions and have collected several B/W guns.
My technique is to use a dental turbine (a dremel will do) and bore an
about half mm hole through the neck downstream of where I plan on
cutting it. That way I can re-open the tubulation in a controlled
manner and reuse it.

[Instrument Resources of America]

Also!!! It is my understanding from being a member of T.C.A. Tube
Collectors Association, another Yahoo group, that once the 'cathode' of
the gun is exposed to 'air' it is DESTROYED, and can NOT be used
again. Ira.

[JohnK]

I was about to reply the same.... then I started to think about what I could
actually quote.

This implies that a cathode gets activated after assemby and after/during
pumping.
What is the chemical during construction?
What is the chemical during operation?
What is the chemical after later exposure to air?
If the chemical after later exposure to air is not the same as that during
construction, can this later chemical be converted to what is required?

I thought I knew this :-(
I have just reached down Materials and Techniques for Electron Tubes
[revised edition of Materials Technology for Electron Tubes], Walter H Kohl,
1960,Reinhold.

John K.

----- Original Message -----
From: "Instrument Resources of America" <IRACO...@HUGHES.NET>
To: <neoni...@googlegroups.com>
Sent: Tuesday, April 29, 2014 9:11 AM
Subject: Re: [neonixie-l] Neon size limitations?

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[Instrument Resources of America]

Hello John,
I do not know all of the in's and out's of it. But I do recall that
a group of early television collectors had tried in vain to preserve
several of the original 15 inch color television CRT's by rebuilding
them, with the help of a CRT rebuilder, who by the way is now long gone.
Not dead, I don't think, just forced into retirement by lack of
rebuilding business, or perhaps even willingly. His equipment for
rebuilding is now in the hands of "The Early Television Foundation"
http://www.earlytelevision.org/ and,
http://www.earlytelevision.org/crt_project.html and,
http://www.earlytelevision.org/15GP22_rebuild_report.html If you
read down through the article in this last link, to the point where you
are at the second sentence, before the heading of ""The Way Forward""
you will read the following sentence,,,,""Then the cathodes are
activated by heating them using elevated voltage applied to the
filaments."""". All of those particular CRT's had gone to air, and it
was a requirement for rebuilding them, that new guns be installed since
the old guns cathodes were all of no use. Some how or other the cathodes
of the guns are indeed activated after assembly, sealing, and
evacuation. After that exposure to air renders them useless. There is a
lot of interesting reading on these pages and tons of photos, plus even
more links. Ira.

[Matthew Smith]

Quoth JohnK at 2014-04-29 11:37 ...
...

> What is the chemical after later exposure to air?

And is oxygen the problem? (And does the problem apply to more recent CRTs.)

Just pondering whether it might be possible to broach the vacuum under a
gas flood (like Ar/CO2) to mitigate damage.

[JohnK]

Ira and Matthew...
I had a browse of Kohl. Chpt 15 is Cathode Materials and Structures,
pages 519 - 573. There are seven pages of References.
If I knew which of the boggins of cathode materials are involved it would be
easier. Too much info :-(

Many cathodes start with a carbonate and cook it during evacuation to
produce the oxide.
An active oxide would react with water and CO2 in the atmosphere (at least).

Other cathodes end up with the active metal available through complicated
reactions.
That metal would definitely react with air - water, oxygen, CO2 and probably
Nitrogen (at least).

No idea if any of the above is reversible. The porous nature of the surface
is critical too - I can see humidity causing probs with structure.

I think I have an RCA Review [journal] that has specific details of a CRT
gun cathode. I was looking for all I could find on interface
resistance/impedance years ago and have a lot of cathode info packed away.

I am off to browse the info Ira pointed at...

John K.
Australia

----- Original Message -----
From: "Matthew Smith" <ma...@smiffytech.com>
To: <neoni...@googlegroups.com>
Sent: Tuesday, April 29, 2014 12:56 PM
Subject: Re: [neonixie-l] Neon size limitations?

[Per Jensen]

Den 28/04/2014 kl. 22.47 skrev Matthew Smith <ma...@smiffytech.com>:

> Quoth Tidak Ada at 2014-04-29 06:13 ...
>> I once opened a 50 cm B/W picture tube to make a lamp of it. I carefully
>> packed the tube in thick blankets and then filed off the exhaust nipple.
>> About one minute of hissing and the pressure was equilibrated. No danger
>> at all!
>
> Aha! I wanted to get the electron gun and base of a CRT, to re-mount into a longer accelerator structure - was wondering how to break the vacuum safely.

Drill a 1mm hole in the anode cap. It's 100% safe, as it's metal - so no glass cracking.

// Per.

[Nick]

On Tuesday, 29 April 2014 09:37:15 UTC+1, zapro wrote:

Drill a 1mm hole in the anode cap. It's 100% safe, as it's metal - so no glass cracking.

I knew I'd been doing something wrong - used to just hit the neck with a #4 iron...

Nick 

[Instrument Resources of America]

Hello John,
Please let us know what you find. Thanks Ira.

[NeonJohn]

OK, I've repurposed 2 gun assemblies. Let me describe the process. As
y'all found out the indirectly heated cathode is coated with a
strontium/barium/calcium carbonate mixture. During processing this is
turned into oxides by simply heating the filament while under vacuum.

When vented to air, the oxides can do one of two things. Return to
carbonates or absorb moisture and turn to hydroxides. The later process
essentially ruins the cathode because the hydroxides are hygroscopic
enough to liquefy and drip off the cathode.

The solution is to ensure that CO2 gets to the cathode first. I do that
by bathing the area where I drill the vent hole with dry CO2.

Once vented, I cut the neck using a hot wire cutter. The first couple I
did I then sealed some 25mm neon tubing onto the assembly, drew a vacuum
and sealed it off. I had to heat the assembly in an oven to about 400
deg prior to that to keep the moisture from the flame from condensing in
the cool parts. That was a pain, involving handling the assembly in
gloves and so on.

what I've done on my last few is cork the open end of the assembly with
a silicone rubber cork and then place it with others in a Cambro
air-tight container that I purged with CO2 and include a desiccant pack.

The Cambro is a restaurant container made of clear polycarb and is very
useful in the shop.

http://www.webstaurantstore.com/3095/square-clear-food-storage-containers-lids.html

When ready to use, heat the assembly as above, seal it off to the tube
of interest and immediately pull a vacuum. The vacuum doesn't have to
be high. Just enough to get rid of the water vapor of combustion.

Include a new getter in the assembly. I use a 10mm getter with a copper
stem that can be sealed directly into the glass.

Make up your tube, evacuate to as high a vacuum as possible, illuminate
the the filament to yellow red heat and seal off the tube. Fire the
getter AFTER sealing off the tube using an induction heater and you're
ready to go.

John

[Tidak Ada]

Ira,

My experience is that cathodes lay in trays in the factory. About 250 n a
tray, that was sealed before it went to the production. So I believe that
exposition to air will degrade the cathode, but not destroy it immediately.
However it could be that the first warm-up initiates a chemical process that
makes the coating vulnerable to oxygen.

Anyhow, getters are more sensitive to exposure to the atmosphere.

John,

That are exactely my thoughts. I bought those trays at the closing
ex-Philips CRT-plant in Heerlen (NL) for Dan. They were all open.
Also some tins with getters, some of what are still sealed under inert
gas(?).

eric

Sorry for the late reaction, but I my provider was down
[e]

-----Original Message-----
From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On
Behalf Of Instrument Resources of America
Sent: dinsdag 29 april 2014 1:42
To: neoni...@googlegroups.com
Subject: Re: [neonixie-l] Neon size limitations?

[Instrument Resources of America]

Hello Tidak,
You are absolutely correct in that the first warm up to 'higher
than normal temperatures' does in fact activate the cathode
material/coating. Go here
http://www.earlytelevision.org/15GP22_rebuild_report.html and near
the bottom of the page, the second sentence just 'before' the paragraph
title of "The Way Forward" reads as follows, "Then the cathodes are

activated by heating them using elevated voltage applied to the

filaments". Ira

[B Otto]

Well, none of my hobbies are "cheap". Energy efficient either!

[B Otto]

About a decade ago I made some incandescent light bulbs out of surplus labware for a client. I made my prototypes with 250 ml e flasks and the final bulbs with 2,000 ml flasks. I had great luck working with the pyrex glass without a cooling oven. Two of the three finals burned for over 200 hours at about 7,000 lumens.

Would it be safe to assume that if I scaled up a classic NE-2 that it would work?

[Tidak Ada]

Hi Eric,

I've been contacted by someone of the Société RACS, located in Saint-Christol-les-Alès (France), because they cease their activity, asking if I could be interested in some pieces or equipments for my collection.

Not really a CRT manufacturer, although they have built some custom-made tubes in the past, their main activity was the rebuilding of CRT's, and you can see nice pictures of their factory here:

http://s281.photobucket.com/user/jhalphen/library/CRT%20Rebuilding%20at%20RACS%20France?sort=9&page=0

The generalization of flat planel screens sounded the death knell of their activities.

Unfortunately, they are located much too far from here...

Cheers,

Giorgio

[Instrument Resources of America]

That is a shame!! The ONLY rebuilding facility now left anywhere in the
world, as far as I know, is the one held by "The Early Televisiojn
Foundation" in Hilliard Ohio, USA. Ira.



On 4/29/2014 2:54 PM, Tidak Ada wrote:
> And again there is closing a CRT rebuilding plant. This time in France. A
> bit too far from my home.
> See the mail I received from Giorgio. No TCA members in the direct
> environment...
> Anyhow, they would have cathodes.
>
> eric

>
>
>
> -----Original Message-----
> From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On

> Behalf Of Instrument Resources of America

> https://groups.google.com/d/msgid/neonixie-l/535F1A7F.6010803%40HUGHES.NET.