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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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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 -
 
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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?
 
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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 -
 
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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.
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Keith Cress
kcress -
 
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Mix-ups. For the win. :)

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).]

GPS_Clock_In_Box_zkimwn.jpg


GPS_Clock_In_Box_display_bt2sf8.jpg
 
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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 -
 
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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
Typical Nixie: :
 
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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.
 
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@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.
 
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