Two ultra fabulous nixie watches currently grace the web. The first was created by Jeff Thomas ( http://www.amug.org/~jthomas/watch.html ). This watch has four small end-view tubes for time display. The nixies are powered using a camera flash circuit and an AA battery. Two button cells power the clock logic. This watch is logic based, and does not contain a microcontroller. David Forbes at the Cathode Corner has the only nixie watch currently available for sale ( http://www.cathodecorner.com/nixiewatch/ ). This watch uses two small side view nixies to display the time. Time keeping is done on a PIC microcontroller. High voltage for the nixie tubes is provided by a boost converter IC and transformer. This watch is powered by a single 'CR2' lithium camera battery.
Both of these designs employ much surface mount mojo. Consider the picture of Jeff's nixie watch: seven surface mount ICs and a dozen or more surface mount transistors. The goal of this instructable is to create a prototype 'poor man's' nixie watch using as few surface mount components as possible. In Part 1:Development Board, we will consider various design problems while creating an all through-hole version of the nixie watch. Part 2: Surface Mount Mojo, will present the final design incorporating a few surface mount components to save space.
Step 1: The Nixie Tube
These tubes are cheap, I think I paid ~0.50 cents each.
These tubes are readily available from tube vendors and Ebay.
These tubes are socketed, rather than soldered, for easy replacement.
These tubes will work at lower voltages (~140 volts @ 0.9mA).
This is a tall tube (its longest dimension being height), so the design will use height wherever possible to save space. The Eagle socket footprint was created using Nick de Smith's value socket calculator:
( http://www.desmith.net/NMdS/Electronics/soculator.html )