Help identifying a tube (not a Nixie!)

[Paul Andrews]

Anyone have any idea what these might be?

[Nicholas Stock]

Taken from the set of an old Star-Trek movie? :)

On Tue, Feb 11, 2020 at 4:11 PM Paul Andrews <pa...@nixies.us> wrote:

Anyone have any idea what these might be?

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[David Speck MD]

Paul,

These appear to be educational demonstration tubes.  The tube on the right of the image has a phosphor screen at the top, and what looks like an electron gun assembly, mostly hidden at the bottom in the cardboard holder.  I wonder if the tube was meant to be used in a "Mass of the Electron" demonstration setup.

The other two tubes have parallel plates with two side electrodes.  I can't make out any structures attached to the side electrode connections.  It's hard for me to imagine what sort of principle they might have been trying to demonstrate.

I wonder if there is a gas fill in the tubes or a hard vacuum.

The corrosion on the side electrode connections indicated that they have been around for a very long time.

Dave

On 2/11/2020 7:11 PM, Paul Andrews wrote:
> Anyone have any idea what these might be?
>

[Paul Andrews]

Thanks David. They are indeed educational tubes: https://en.m.wikipedia.org/wiki/Teltron_tube

I wonder if you could make an oscilloscope clock out if the cathode ray tube? Assuming they have the deflection coils.

[Richard Scales]

I can actually remember being 'educated' with tubes like these - physics was one of my favourite subjects at school - I must have been about 11 or 12 years old at the time, perhaps 13 at a push and I seem to recall it was all about illustrating electron flow and the effects of magnetism on it.

Happy memories!

[David Speck MD]

Paul,

The Teltron tube would not have electrostatic deflection plates inside.  The mass of the electron experiment was done with two Helmholtz coils outside the globe, as shown in the Wikipedia page. 

You would have to add X and Y deflection coils to the tube to make a scope clock.  Not an easy chore, but the results would definitely be interesting.  As I understand it, most scope clocks are designed with electrostatic deflection CRTs.  Driving magnetic deflection coils at a high enough rate might prove to be a problem.

I'm still not sure what principles the other two tubes were intended to demonstrate.

Dave.

[Mac Doktor]

On Feb 12, 2020, at 12:11 PM, David Speck MD <dr.s...@davidspeckmd.org> wrote:

Driving magnetic deflection coils at a high enough rate might prove to be a problem.

Just some rambling thoughts...

The size of the tube is a major factor. I have an Atari Tempest video game (the real thing that you drop quarters into) with a color vector display. 19" CRT and magnetic deflection. Output transistors for the deflection amps are bog-standard NPNs in TO-3s. Well, that's true of the Wells-Gardner monitors at least. The original Atari monitors were OEM and used a custom HVT that was prone to failure and expensive to purchase from Atari. Most coin-ops switched them out for W-Gs and saved lots of money in the long run.

Anyway, the game has a second PC board—a math coprocessor built from discrete SSI/MSI logic. I'm not certain but it was probably used for rotating lines (computing the square roots at least) and possibly calculating the slew rates for the vectors.

Atari made several games like this. Tempest is by far the best of the lot (Star Wars is fun but too repetitive followed by too difficult). IIRC, Star Wars had an even bigger coprocessor board for heavy lifting as the graphics were wireframe 3D.

Now my brain is all shook up. I can't remember half of this clearly anymore. I'm sure there are forums all over the 'net where all of it has been disassembled. The original games had all sorts of copy protection, possibly encrypted object code. What I do remember is that I paid $65 for it in 1992. I have a buyer lined up; I'm giving him a bargain price of $500. In it's present condition, perhaps with a little clean-up, it would go for a lot more on ebay.

OK, back to the original topic...

Terry Bowman, KA4HJH
"The Mac Doctor"

https://www.astarcloseup.com/

“The book said something astonishing, a very big thought.
It said that the stars were suns, only very far away.
The Sun was a star, but close up.”—Carl Sagan, Cosmos, 1980