This is my latest "thing"...clocks with valves in them!

Nixie tubes were used in all manner of early electronic instruments (ie commercial scales, bench-top multimeters, etc).  Production ceased around 1970 however, you can still pickup one or two if you look hard enough.  From what I understand, they are essentially an early form of a neon tube.  Typically they contain the numerals 0,1,2....9 and, some have +,-,~ too.

E. Barbour (chief designer, METASONIX, and senior editor, Vacuum Tube Valley) has provided me with the following background information on Nixie tubes:

The idea dates from around 1915--there were several patents for similar devices before WWII. National Union made such numeric displays around 1940, they used bent wires to form numerals and had large 9-pin bases. The Haydu Brothers Co. developed what we call Nixies today circa 1948-- Burroughs bought the Haydus out in 1952, making all their display tubes (and their complex "Trochotron" counter tubes) into Burroughs products. After Burroughs was absorbed by Unisys, tube manufacture ceased--however, companies such as Richardson/National and Philips were making Nixies well into the 1980s. Richardson still has the special tooling to make them, and could make more if demand appears. Prices for NOS Nixies are rising, because so many people are building clocks and fooling with old test equipment....

A closeup of a nixie tube...

My plan was to build a clock incorporating modern IC's  and a crystal for the clock function, and use the nixie tubes for the display.  A couple of web sites that have inspired me are:

http://www.electricstuff.co.uk/nixclock.html

http://www.fortunecity.de/wolkenkratzer/westend/696/nixieclock/ncp.htm

There are a few similar clocks on the web, just use a search engine with the key words "nixie" and "clock".

Here are a selection of photos of my clock 'mid construction'.  I've based it on a GNP-7AH nixie tube and a quartz crystal for the timing:

The photo above was taken in the early stages while I was testing the clock on the workbench.  As you can see it goes!

 

Here are a couple more construction photos.....

 

This is the finished product.  

The clock keeps time extremely acurately now.....I originally had probelms using a crystal for timing but now I use the 50Hz mains pulse. 

Here's a close up of the Nixie tube (GNP-7AH) and the hard to find pin out data: