Russian Polyatron A-201 driving a Burroughs B-5092 Nixie!

[Dekatron42]

Hi all,

 

I have finally succeeded in hooking up a Russian A-201 Polyatron so that it drives a Nixie, a burroughs B-5092, and counts just as it should!

 

Have a look at my new clip here: http://www.youtube.com/watch?v=R6D-j3PpoTY

 

/Martin

[kay486]

Now this is quite awesome i got to say!

[Dekatron42]

Thanks!

 

I finally got hold of a few A-201's a few weeks ago and have been thinking about how they should be connected ever since the discussion here on the forum a few weeks ago. Yesterday I started to experiment with them and after a few tries I managed to get a stuttering count but today I succeeded in putting it all together so that it works properly.

 

I just now increased the speed of the oscillator and made a new clip: http://www.youtube.com/watch?v=Ica8ETl4Adg

 

/Martin

[threeneurons]

Nice !

This is the way technology would've went, had they not invented semiconductors. I'm painting up some picket signs, and going up to Silicon Valley !

[Dave]

A W E S O M E.  Can you post the circuit?

[Dekatron42]

Thanks!

 

As soon as I have a finished version I'll post it here.

 

I have to check the limits of the voltages and currents for my circuit so I can compare those to the datasheets so that everything will be within tolerances, I don't want anyone to damage their rare Polyatron if they try my design. I'll also try to check design by making some calculations so that I know that it will be within tolerances.

 

Now that I have something that is working I am going to discuss this with some friends so that I can be sure that the design will work within the tolerances for the A-201.

 

I found out that one of my A-201's have a loose guide electrode so it does not count correctly when passing the figure 2, it sometimes skips that figure since the second guide electrode is not properly connected to the common ring connecting all of the same guide electrodes. I'll try to see what happens if I run this polyatron outside of its tolerances, raising the voltage and current and see if I can get the electrode to pass some current then. The small welding on that electrode looks poor and the mica sheet surrounding that electrode also looks murky and poor so it might be a manufacturing fault. There is also a few loose pieces of the white insulation used on the cathode and screen electrode wires in this tube.

 

I also have some more experimenting to do since there is not a lot of information to go on when testing these polyatrons. I still haven't figured out the proper voltages and currents for all of the different bias and screen electrodes. There is a little spread in voltages and currents necessary between the working A-201's that I have to get them to run properly - I'll try to check the limits and also find the proper working conditions. All of them run at one setting of voltages and currents but the tolerances are very close then so I'd like to find proper working conditions.

 

I have discovered some things that differ from driving normal dekatrons and that is that these polyatrons are prone to self oscillations like a neon lamp circuit with a capacitor. They are also showing a different behaviour on the guide electrodes compared to dekatrons, there is a negative pulse produced by the Polyatron guide which disturbs the counting during some circumstances. I don't fully understand why this happens right now and I have only been experimenting for three days and just a few hours each day with them so I still have a lot of experimenting to do ahead of me.

 

Does anyone know if these polyatrons were marked OTK or not? None of mine have that mark so I am thinking that they might not have been quality controlled.

 

If anyone has more information on these rare Polyatrons please send me an email!

 

Just now while writing this I suddenly becmae aware of one fault in my design, while just thinking about it, so that will have to be fixed, maybe that will make the circuit work better!

 

/Martin

[Marcin Adamski]

Hi Martin,
just very shortly: My only A201 is stamped OTK 6. It is a week vertical
stamp on the right side of the tube symbol. Super to hear about your
progress. I am so behind with everything that my own rear is in front of
me right now.
Marcin

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[Dekatron42]

Hi Marcin,

 

I went and had a check on my A-201 under a sharp lamp and on the one working best there are actually very faint traces of a purplish looking stamp but I can't say what it should read but it could be the OTK stamp, the others have some traces of black ink in that position but I can't see what it reads at all as there is to little left. All of the rest of the text and ink is black and easy to read even though it is starting to fall of. The pins were partly bent when I recieved my A-201's so they might have been used, at least they have not been stored properly.

 

/Martin

[Jon D.]

Hi Martin,

Congrats on your success!

I have four A-201s.  The two that have a date stamp of 1281 are clearly stamped with a purple "OTK 6" (one is super sharp, the other very faint but readable).  The one with a date stamp of 1282 has a purple stamp with only "OTK" on it and no trace of a digit (perhaps the "6" rubbed off?).  The one with date stamp of 1083 has no OTK stamp and no trace of one at all.  All of the "A-201" labels look brand new as do the tubes themselves.

I look forward to your circuit.

Jon

[Dekatron42]

Thank you Jon D. and Marcin for your input on the OTK markings. It turns out that mine once had marking which have been rubbed off due to much handling. My A-201's looks like they have been used since they have bent pins and almost no OTK markings left, I could just see some traces of markings when I looked under a bright light.

 

Today I spent some time to modify the circuit according to a design shown in the article "A new poly-anode counting tube, the ‘Polyatron’" by Y. Hatta ; H. Mase ; M. Sugawara published in Radio and Electronic Engineer, Volume 26, issue5, November 1963, p. 383 – 388 - however it does not give me the operating conditions that I am looking for so the experiments will have to continue.

 

With this driving mode both guide electrodes, G1 & G2, flash for every step - since there is little or no information on these Polyatrons I can't say if that is the correct behaviour or not - at least the voltages on all electrodes looks better in this mode.

 

I just posted to new short films on YouTube showing this new look, one slow and one fast counting sequence: http://www.youtube.com/watch?v=At6Iq_reUSQ & http://www.youtube.com/watch?v=A41YBbGdeI0

/Martin

[Marcin]

Would it be possible that the guides' current is to high?
Marcin

[Dekatron42]

Hi Marcin,

 

Yes, it might be that which is affecting the whole circuit. I'll look more into that. Thanks for the tip!

 

/Martin