So I have seen lots of Nixie clocks online and thought they looked great, however I didn't want to spend $100+ on a clock that doesn't even include the tubes!
So with a little electronics knowledge I hunted around the various nixie tubes and circuits. I wanted to make something a little different to the large range of generally fairly similar looking nixie clocks. In the end I opted to use Nixie IN-9 bargraph tubes. These are long thin tubes and the height of the glowing plasma depends on the current through the tubes. The tube on the left is in hour increments and the tube on the right is in minutes. They only have two leads and so make building a circuit more straight forward.
In this design, there is an hour and a minute tube, with the heights of the plasma in each tube representing the current time. The time is kept using an Adafruit Trinket microcontroller and real time clock (RTC).
There are two sections, first the electronics and secondly the mounting and finishing.
The electronic components required are:
Adafruit Trinket 5V - $7.95 (www.adafruit.com/products/1501)
Adafruit RTC - $9 (www.adafruit.com/products/264)
2x Nixie IN-9 bargraph ~ $3 per tube on eBay
1x Nixie 140v power supply ~$12 on eBay
4x 47 uF electrolyte capacitors
4x 3.9 kOhm resistors
2x 1 kOhm potentiometer
2x Transistor MJE340 NPN high voltage ~$1 each
1x LM7805 5v regulator ~$1
1x 2.1mm socket ~$1
1x project box with pcb ~$5
1x 12v DC power supply (I found an old one from some long forgotten gadget)
Solder, hookup wire, etc
I decided to mount the electronics in a small black plastic project box, then mount the tubes on an antique clock movement. To mark the hour and minutes I used copper wire wrapped round the tubes.
Antique clock movement - $10 eBay
Copper wire - $3 eBay
Hot glue gun