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Nixie Tube Grid??
3

Nixie Tube Grid??

Nixie Tube Grid??

(OP)
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:


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 - http://www.flaminsystems.com

RE: Nixie Tube Grid??

Are you sure it's a Nixie tube and not a VFD? The grid makes me think it's the latter...

That said, "grid" is often used to describe the anode cage

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Nixie Tube Grid??

VFD?
Volunteer Fire Department
or
Vacuum Fluorescent Display.
Wiki:Link
(Thanks to MacGyverS2000's hint)
Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Nixie Tube Grid??

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. smile

RE: Nixie Tube Grid??

(OP)
Dan; Definitely a Nixie tube. The rest of the data sheet states "High Brightness for Outdoor Matrix Displays". Came out before VFDs.



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.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Nixie Tube Grid??

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.

RE: Nixie Tube Grid??

(OP)
Scotty; I still have to lay it out so I think I can add that and just not stuff the parts if it ends up not being needed. Thanks.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Nixie Tube Grid??

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
http://www.Hi-TecDesigns.com

RE: Nixie Tube Grid??

(OP)
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 - http://www.flaminsystems.com

RE: Nixie Tube Grid??

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
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Nixie Tube Grid??

(OP)
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 - http://www.flaminsystems.com

RE: Nixie Tube Grid??

(OP)
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 - http://www.flaminsystems.com

RE: Nixie Tube Grid??

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
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Nixie Tube Grid??

Found extra tubes here for $3/pc:
https://tubes-store.com/product_info.php?products_...
Could probably find cheaper, but that was the first Google result. For that price and $2/socket, I'd solder them puppies directly to the PCP and purchase a few extra IN28s as spares.

Also found this Google Group discussion on driving these things... I think you'll find all you need there:
https://groups.google.com/forum/#!topic/neonixie-l...

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Nixie Tube Grid??

(OP)
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 - http://www.flaminsystems.com

RE: Nixie Tube Grid??

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
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Nixie Tube Grid??

2
(OP)
For your viewing pleasure!

The Nixie Clock fabbed boards. The silver thing is a quarter for scale.


Keith Cress
kcress - http://www.flaminsystems.com

RE: Nixie Tube Grid??

Crikey...

RE: Nixie Tube Grid??

Top indicator should be marked "00", not "60".

winky smile!!

RE: Nixie Tube Grid??

How come you get all the fun!

STF

RE: Nixie Tube Grid??

(OP)
LOL! You're right VE1BLL!! Luckily none but you guys will see this. The finished product will only show the actual tops of the tubes. Oh and notice the numbering is backwards? I was planning to stick the tubes out the back but by the time the layout was done I realized I should put them on the front since all the parts are a twentieth as tall as the tubes anyway. sigh. I'll fix it all in the SW LOL.

Battery: I've got a different design that doesn't use evil Lithium batteries but then it dawned on me these clocks will weigh about 35 lbs. No one is going to try shipping these by air - so I left in the superior 2032 cell design.

Spar; !! I've never designed a board even half this size.. well yeah, half this size yes, but not ROUND!! It's waaaaaaaaYYYY too big to fit in my entire process chain so I'm going to have to hand solder it all. -Not so fun-

Keith Cress
kcress - http://www.flaminsystems.com

RE: Nixie Tube Grid??

re. Tubes on front vs back side of PCB

If you install the 'Nixie' tubes on the opposite side of the PCB than planned, then the non-symmetric pin assignments of the tube would mean that the tube pins would be in reversed 'clockwise-edness' compared to PCB pin assignments.

i.e. the Plate and Grid swapping places around the missing pin, for the tube described above.

Is the PCB opposite-side tube reverse-clocking compatible?

RE: Nixie Tube Grid??

(OP)
Damn. I think you have a good point there.. I'll check how I made the 'device' but I may be stuck with the tubes out the back.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Nixie Tube Grid??

I'll suggest soldering 2-3 tubes before doing an entire board... ya know, to make sure you haven't swapped something else wink

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Nixie Tube Grid??

(OP)
Oh yeah Dan... I'll be piecing that thing together. For starters I need to commission two of those high voltage supplies. Then I'll do one of each tube and the CPU.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Nixie Tube Grid??

Keith,

When you write the software for the clock, will you include some "Special Effects" for certain times/dates (e.g. 0:00 01 Jan)?

RE: Nixie Tube Grid??

(OP)
Possibly, though I'm not sure what your specific example would conjure up. I have very little extra current available for the big tubes so I will likely not be able to even turn more than one on at a time. The clock will run a 'second hand'.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Nixie Tube Grid??

(OP)
VE1BLL; I just reviewed the big tube layout and it turns out I 'made the device' from the top as is normal and then didn't mirror the part onto the board so I have to have the tubes off the front! Just as I now want them. When a miss equals a hit.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Nixie Tube Grid??

Mix-ups. For the win. smile

Where will this huge Nixie tube clock originate its time reference? It'd be a shame to be big and amazing, ...and 17 seconds off.

Something like this impressive clock should be within a heartbeat of precisely-accurate.

By way of example, only a few days ago I finished up a cute little "GPS Clock In [a tiny] Box". It's the usual borrowed and adapted software, an Arduino Nano, an old uBlox NEO-6M GPS module, and a blue 1602 LCD display with I2C backpack. They're all packed into a comically-tiny wooden craft box from the dollar store. The little wooden box came with a glass covered window in the lid, which was just about perfect for the 1602 LCD display; so the overall design almost wrote itself. The overly-thick USB power cable runs out the back. Other than about a half-second of latency, it's inherently perfectly accurate - which is nice. The Arduino Nano doesn't do anything other than reformat and pass along the GPS time, so it is what it is (i.e. accurate, or frozen display [perhaps a To Do item).

[EDIT: The black box on the other end of the cable is just a USB Power Brick (battery).]





RE: Nixie Tube Grid??

(OP)
That's nice work!


There's a WiFi clock setter I was going to use but the customer nixed it. Just buttons on the side and battery backup. I did provide up/down buttons and even seconds adjustment. They might need to adjust it once a year but I'd take that over re-setting clocks every time the power blinks.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Nixie Tube Grid??

Interesting device. Looks like the Russians have co-opted the 'Nixie' name for non-Nixie parts. Nixie tubes are cold-cathode, so there's no heater and no control grid and they light at 170VDC. They tend to live a long time and be somewhat dim. It's an interesting tid-bit in the Wikipedia article that the original BCD decoder-driver ICs that were designed to drive the high voltage are rarer than the Nixie tubes and are typically replaced with discrete transistor designs.

Lots of options to play with the peripheral LEDs https://youtu.be/KD9erDrjtEA?t=138

Typical Nixie: :http://www.ebay.com/itm/6-PCS-Vintage-IN-8-NOS-NIX...

RE: Nixie Tube Grid??

Some of the nicer RTC chips have TCXOs.

E.g. "The [Maxim] DS3231 is a low-cost, extremely accurate I2C real-time clock (RTC) with an integrated temperature- compensated crystal oscillator (TCXO)..."

They're as cheap as chips, even in the better TXCO version. Complete DS3231 modules on eBay are typically US$1.33 (shipped).

Good luck.

RE: Nixie Tube Grid??

VE, perhaps consider running a standard clock in the background to keep somewhat accurate and useful data when the GPS clock goes down. You could also light a few segments in the corner to indicate GPS signal is down and the displayed time is "approximate".

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Nixie Tube Grid??

@Dan - Yep, the US$1.33 each DS3231 RTC modules are already on the way. Unfortunately, Canada Customs at the Vancouver Port of Entry is reportedly backlogged, apparently by as much as two months at times. So it takes 'forever' (3-4 months) to get parts. On the good news side, I made sure at the outset that my house was fairly RF transparent (not joking), so GPS signals are reliable even in the basement. Next, I have a WWVB 60kHz receiver module to do another Arduino clock project. These days, this sort of thing is very cheap entertainment.

RE: Nixie Tube Grid??

I wouldn't worry about an RTC, I'd just go straight crystal timekeeper. With proper tuning caps on the crystal and at indoor temps, I can easily see less than several seconds/month accuracy. Since that would only be used as a backup during the short time periods you can't get the GPS signal (a day, maybe two at the most?), most users would never notice a difference.

To me, RTCs mean loss of power protection and coin cell batteries for the backup... do you really need to go down that road?

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Nixie Tube Grid??

(OP)
Good eye IR!



I've used this RTC for years and years. It's cheap, has a bunch of static ram to keep settings in, that won't burnout like EEPROM and runs for yeeeeears on that particular battery, and won't run on the battery unless power has failed.

(I do find I have to lacquer that bit of circuit to prevent 'funny business' from bothering it.)

Keith Cress
kcress - http://www.flaminsystems.com

RE: Nixie Tube Grid??

I would scrap the entire thing. And make little pizza slices. Six or twelve of them. Even two halves may work.
Make a heavy center board with all the common stuff on it. Bolt (or wide-solder) the slices ground-planes to the center and use little ribbon cables to connect to the slices.
Then, you can fit it into your process and avoid hand-soldering.
Less work. Better reliability. Better economy.

I know that you will hate this - at first - but give it a thought.

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

RE: Nixie Tube Grid??

For making more than, say 10 of these clocks, the extra work in soldering jumpers between boards would be a poor ROI, in my opinion. In many cases, the extra expense in just making bigger boards is worth it. But I suppose only Keith can be the true judge of that.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Nixie Tube Grid??

IDC and ribbon is an alternative that I had in mind. Or board2board connectors.

The smaller size of the boards may be an important factor. That is what Keith said somewhere higher up. The board, as is, seems to be oversized for his soldering machine. But the customer may think that a "monoboard" solution is more reliable.

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

RE: Nixie Tube Grid??

(OP)
Well.. The boards are fabbed already. I've hand soldered dozens of SMD boards and don't actually have much problem with it other than it takes time. In this case there are actually only about 100 SMD parts and most are two pin and go really fast. I got those mondo boards for a mere $22 apiece delivered. Breaking the boards into oven - fitting pie slices would incur:

1) ~ six times the number of boards. The boards would be cheaper per but the shear quantity would likely treble the board costs if not more. Shipping one board order is ~$40. I'd be hit with $240 in shipping alone.. More than these cost in total.

2) These boards in pie shapes would likely still fill my small reflow oven with just one or maybe two boards. ~25 minutes per reflow cycle. 8 complete clocks, six slices; 48 boards. Say two fit the oven, 24 oven cycles. 24 x 25 minutes = 10 hours babysitting reflow. (Just shoot me!)

3) Would need some harnessing to convey signals to the various slices. We're talking 350 volts here which exceeds most ribbon cable systems.

4) These clocks have 204 thru-hole leads that need to be hand soldered anyway just due to the tubes. SMD solders ~3x faster than thru-hole.

I'm good. Really!

Fun discussion, thanks!

Keith Cress
kcress - http://www.flaminsystems.com

RE: Nixie Tube Grid??

"$22"

It's mind-boggling how cheap, easy and fast custom PCBs have become. That industry segment deserves a medal, or a cake, or something.

RE: Nixie Tube Grid??

I just realized that there's more to it than I could imagine. I fear hand-soldering small SMD like the washing machine. Could be the combination of reduced hand stability, weak sight and laziness. In other words - aging sets in.
This is another of those threads that turn every stone to come up with the optimum solution.

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

RE: Nixie Tube Grid??

(OP)
VE1BLL; I could not agree more!

Hi Gunnar. Indeed! Love the intelligence and broad experience the fine people here have and share.

To your list I have to include getting old adds the horror of sitting in one place for a long time which causes me butt and leg aches and pretty much is what controls the production process.

Keith Cress
kcress - http://www.flaminsystems.com

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