You probably seen somewhere those cool looking retro displays with tubes sticking out – aren’t they cool? Depending on the type of tube used they can display a range of numeric information and some variants could display letters too! These tubes were known as cold cathode display – CCD – (now more commonly known as Nixie tube) or vacuum fluorescent display – VFD.
Nowadays it’s kinda impractical to use these casually in various instruments but they sure look awesome when used to display time. It happens sometimes with my projects that ideas come to me after I receive a cool thing to disassemble. This was one such time.
A custom made soviet-era scientific instrument with a load of IV-12 (ИВ-12) fell into my hands and I just had to disassemble it and salvage those tubes knowing that they can be used for really interesting stuff.
Here’s what was inside:
For a while I already had an original VFD clock Elektronika-4 but it was malfunctioning lately. The time would advance faster so it always displayed time in the future, something was off with its circuitry and I wanted to replace it.
I suppose if you really wanted to you could find these barely working Elektronika or similar desk clocks in flea markets for very cheap and salvage the tubes.
So now that I had the tubes I wanted to make a desk clock and there’s a whole lot of examples of how people get creative with this type of a project, there’s even a community with people sharing their creations! But this time I didn’t want to create a board myself so I set out to search for one to buy thinking there’s surely had to be something out there.
Mostly what I found was pictures, people that created these didn’t share their PCB projects most of the time and I didn’t really want to order a plain PCB to solder dubious components myself. Situation was complicated because I had IV-12 tubes but all boards that I found was based on IV-11 tubes. While these tubes are essentially the same there are some differences – IV-11 has a decimal point while IV-12 does not so the pin count is different and their arrangement differs. Otherwise these tubes have the same parameters and can be exchanged.
Eventually I settled on a IV-11 based board that I found on AliExpress which comes with a nice wooden base.
If you just have IV-11 tubes you can stick those in and be done with it :D
While I was waiting for it to arrive I was searching for information how to make an adapter. Interestingly you can buy various adapters for various tubes but none for IV-12…
I found a nice PDF document with both tube’s information complete with a drawing which I preserved here then made an adapter in EasyEDA and ordered that from JLCPCB.
The IV-11 tube has one pin for a decimal point. When mounting IV-12 that pin can be left unconnected.
These VFD tubes can eventually burn out and will need to be replaced. You can buy pins that you can solder into your PCB to seat in the tubes nicely. Those pins will get soldered on the adapters and then connected with wires to appropriate pins.
There was a great deal of head scratching and searching for bits of information while trying to figure out how to connect the pins. The number of pins is different and their locations differ.
Looking at the diagram you can see the pinouts. The first thing you may notice is that the pinout for IV-11 is for some reason rotated – there’s a gap between the first and the last pins for alignment and that gap is at a different place on my clock PCB. Also the PDF doesn’t mention if the pinout is top-view or bottom-view…
Eventually I found a blog post with correct pinout rotation and explanation that it’s bottom-view.
Now I knew in what direction the pins go, I mapped out the pin connections by looking at the PDF, there are pin numbers written next to their segments.
Below is a IV-11 pinout borrowed from that blog.
And I began soldering away.
I soldered the tube pins into the adapters and into the board I soldered pins to which I soldered wires for connections. I had to use wires because the pins get intertwined.
Because of all this the height increases and so I had to make a bracket to mount my adapters and hide the pins. I modeled that in OnShape and lasercut from different thickness of plywood and used a wood stainer to give the whole thing some color and make both pieces – top and bottom – look similar.
But that experiment didn’t turn out very well and I didn’t like the result at all. I decided to go for an open, industrial-ish design which was even simpler to make and so I modified the CAD drawing (multiple times) and laser-cut parts from black acrylic.
After that I saw that it’s missing a pin cover for all the lamps and so to make it look more complete I 3D printed some covers and that made it look much better.
Used M3 hex bolts to tie it all together and the result was really cool. I now have a proper clock :D
