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Nixie Tube Grid?? 4

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itsmoked

itsmoked

Electrical
Feb 18, 2005
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I'm tasked with designing a wacko Nixie Tube clock. I have to use the IN-28 which is a Soviet era tube that is just a single bright dot about an inch in diameter.

Here's the pertinent data sheet page:
IN-28_Nixie_Tube_leyy8z.png


Normally one hooks the B+ voltage to a Nixie's Anode (a metal screen) and each of the digits is a cathode that gets grounded to light it.

Well-and-fine, but this particular tube sports a Grid pin too. See pin 1 - Cetka. Cetka means 'Grid'.

Any of you tube-heads know what I should do with it? Do I ignore it?

Pins 2, 5, and 6 are NO-CONNECTION.
3 and 7 are ANODES
4 is the CATHODE

I'd be nice if anyone also knew if the diagram was viewed from below or above too. The tube is hard to see into since the sides are pretty obscured.


Keith Cress
kcress -
 
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My limited knowledge of valve technology is that the grid should be biased with a potential divider to an intermediate voltage, not left floating. Bias to roughly 2/3 of the anode voltage relative to the cathode would be a guess as a starting point. Having only seen a handful of Nixie tubes in my life, I don't know if that helps much as I haven't played with them before. Interested to see how this develops. :)
 
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Dan; Definitely a Nixie tube. The rest of the data sheet states "High Brightness for Outdoor Matrix Displays". Came out before VFDs.

in-28_mfpu6o.jpg


Scotty; Ugh. This design is already a major time consuming headache needing a 5V supply a 65V supply and a 250V supply all fed from 12Vdc. Having to add a fourth.. Shudder.

IR; That makes sense. Especially since these were used in huge stadium sized displays where often they were multiplexed. Wish someone had a circuit for them. I've searched everywhere. At this point I probably need to ignore the grid and run them the same way everyone else runs the standard ones, which have no grid.


Next hurtle is trying to mount them. I was going to mount them in pin sockets so they could be easily replaced but 50 cents a pin and each clock having 204 pins that would cost $1,632 for this build of 8.
URL]


Keith Cress
kcress -
 
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Hi Keith,

I was thinking more of a resistor bias chain, no external supply. Might be an adjust-on-test job though, so if you're using loads of these things then it might not be viable.
 
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You can find cheaper... $2/socket, PC-mount, so total cost is now <$60 per 5x6 array. And I didn't look very hard.

But generally this stuff isn't socketed. If you think you'll need to replace, create a PCB that is modular and would allow replacement of singles (or a small number of units... a 1x5 board might be nice).

Dan - Owner
URL]
 
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Dan; I couldn't find tube sockets that cheap(!), not to mention these tubes aren't a standard tube spacing, though they could probably be bent to fit.

I also thought of sub-tube-boards as a quick, cool way to swap-out tubes but immediately ran up against the same screw-machine-pin cost problems only 2X! since now you need pins on the little boards and sockets on the main board.

Keith Cress
kcress -
 
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This doesn't look like a Nixi (Burroughs Numerical Indicator, Experimental #1) at all. More like a gas tube with a control grid. The grid lights the dot and you will need many dots to produce a legible character. Which I think that you already know. But a Nixi - nope.

My wife reads Russian - somewhat. Are there any data sheets?

Pins are always seen from the bottom, as opposed to IC legs.

Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
 
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Hi Gunnar. It's definitely a Nixie Tube and certainly not the usual 10 digit kind. It's simply a dot - a big bright dot. They will be the 12 hour markers.

I attached a pdf of the data sheet.

Link


Thanks for the bottom tip. I figured it out by finding those two pins that are tied together (anodes) which quickly identified what you describe.

Keith Cress
kcress -
 
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Oh wow Dan. Thanks! That's only $97 for all the sockets I'd need. That's palatable. I need
to see if they'd hold the pins which are just wires on these IN28s.

I wonder if they have any sockets for two pins. I'd need 500 of those.. I'll dig around.

Keith Cress
kcress -
 
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You will need some hardware to keep them in place. They fall out of ordinary sockets very easily. My tip: Solder them to the board. Life is usually quite long and you vill probably never see one of them die. If one dies, it is easy to solder it away and put a new one in. But if you put them in a socket you will have problems. Unless they are vertical. But a display usually isn't.

BTW That guy that calls them Nixie tubes is wrong. They are NOT Nixies. Nixies do not have grids and they are per definition showing numerals (N in Nixie stands for that). Not that it matters what you call them. But I like correct terms.

Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
 
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Yeah, you can charge anything you want for something you don't have. LOL.

There are some IN28s about. Usually small lots for ~$100.

Gunnar's probably correct that the sockets might not play..reliably with those leads. My issue is that these clocks -this is a product- weight about 50-lbs. So having a customer ship them back is painful all the way around. On the other hand having things plugged into 240V that a user might figure out how to unplug is also a problem..

Keith Cress
kcress -
 
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A thought: Put as many OLED displays as you want in a row and make them show the bleak orange neon glowing numerals by presenting .jpg or .tiff photographs of the REAL THING on them. No-one, except you, will notice.

Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
 
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