Projects

Nixie Clock

I have a set of nixie tubes which I bought on ebay a few years ago.

The nixies

These are four Hivac XN11 tubes

They are driven at about 170v DC with a 33k resister inline on the anode.

Cost: Can't remember, but little enough for me not to have got in trouble for having bought them on a whim and left them in the attic for 7 years.

Pinout: (bottom view, with gap up) starting at right and going around clockwise, Cathodes 1,2,3,4,5,6,7,8,9,0, ending with the Anode by the gap on the left.

The driver and nixie board

Given my limited electronics experience and general unsafety around high voltages I decided to use an existing kit to drive the nixies: Ardiunix

Cost ~30 plus VAT

The controller and electronics

The basic platform is a bog standard Arduino Diecimillia

At the moment it's running stock code but I'll get around to writing something more interesting (fading?) eventually

I have a 60Khz Rugby (as was) clock receiever ( ~8 inc postage) which I plan to connect to the arduino once i've figured out an MSF decoder

Nixie Board.

The nixies are wire-lead type, so need a custom board (or lots of wiring!) to connect them to the arduino. The arduinix can drive two 10-way cathode busses and has 5 anode busses which can be multiplexed.

In theory I could drive all four nixies off a single cathode bus bus but i'm using both with Hours and Minutes on seperate busses.

I have never designed a PCB before, and despite several attempts to learn "proper" CAD tools (which you don't really need as all you are doing is routing pads to pad), I gave up and used inkscape.

Two things are evident in the design:

  1. I clearly don't know what I am doing
  2. I might have got a bit carried away

Power

The arduino has a regulated PSU which provides 9v to the arduinix, driving the board at 12v seems to work best.

Build

Basic testing

I build the arduinix and rigged up a single nixie onto a breadboard:

The resistor stack on the right is empirically about 33K

And it works!

w00t.

I then tried four nixies in a clocky sort of way, In the process I seem to have burned out one of power transistors which control the first anode pin. Fortunately there are three and I only need two.

Attach:.small.jpg Δ Δ

Case.

The plan is to make a cast concrete case (about 3 inches by 6 inches by 2 inches) with the nixies sticking out of holes in the top.

I'll get aronud to doing this eventually.