Three Wise Men

Assembly of a Nixie Clock

Image via Wikipedia

A while ago¹ I decided that as a geek I need to equip myself with binary clock or a digital clock made with Nixie tubes. Until now the idea was brewing. It was almost 15 years since I designed a circuit board by myself and it was a little less time ago when I was soldering something. I had to find an already made kit that didn’t require designing the circuitry from scratch. Pretty soon I ruled out the binary clock since they can be easily obtained in any geek store. Nixie tube clock is a completely different story altogether. Tubes are nowadays relatively rare and much harder to get. After some digging and my distrust to purchase a bunch of easily shattering glass tubes on e-bay, I found tubehobby.com which offered various nixies and complete clock kits. For a relatively low price of $99 I ordered complete nixie clock kit. Kit included all the electronic parts and the Nixie tubes. There was no power supply and casing. Power supplies are easy to get and you’ll be able to find one in your local radioshack store.

Kit from tubehobby.com had basic online instructions on how to assemble it, what kind of power source is required to drive the clock and few tips about setting up everything.

Assembly was fun and memory reviving experience. I do recommend that you use sockets for integrated circuits since they are more delicate and harder to replace if you damage them with too much heat at soldering. When you buy chip sockets² make sure you double check what you’re buying or you’ll end up like me. With one wrong socket and a decision about waiting one more day with the assembly³. Instructions were clear and easily understandable, but you’ll need a background in electronics and circuit design if you want to make this to work. If you never held a soldering iron in your hands I recommend that you get someone to help you.

Two things that gave me a little headache during the assembly. Setting the firing voltage for tubes – there is a small potentiometer on the board and a capacitor where you need to measure the output voltage of the driver⁴. A slight, tiny move of the potentiometer changed the value by 10V or even more, so finding that 160V was quite a task. Second problem was more of a dexterity issue. See, the tubes have 13 long and bendable pins that need to go through 13 tiny holes that are very close together. It took me about 5 minutes to insert each tube. :)

Apart from one broken separator bulb, kit from tubehobby.com was perfect. I am not sure if separator bulb was broken during transport or if I fried it when I connected the clock for the first time. Separator bulbs can be set in three different modes. They can blink once per second, then can be used as an AM/PM indicator if you use 12h clock format, they can be constantly lit or you can switch them off. Only one bulb was working for me and I found the blinking highly annoying. I turned it off and I’ll probably remove both bulbs from the circuit board sometime in the future.

Of course, you need to see the video of nixie clock in action.

1. Couple of years ago actually. [↩]
2. They are not included in the kit. [↩]
3. No, I didn’t wait, I soldered one chip directly to the board. [↩]
4. You’ll need a voltmeter for this. [↩]

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