This page consists of some pictures and description of a nixie tube clock I built after I finished my first circuit course in college (winter break after fall semester 2009). I designed almost every aspect of the board myself, from the power supply to the control circuits and logic for the displays. At the center of the project is an Atmel uC running the arduino bootloader.
The HV power supply is a Boost converter where the uC controls the switching frequency. This makes it super easy to change the output voltage. If I were to do the project again I would add a feedback mechanism via the A2D converter onboard the arduino so that the uC could automatically regulate the voltage.
First demo of Nixie tube working
Demo of two tubes. You can see the power supply in the background (with the big orange cap). I did a lot of testing on the power supply at this stage.
Here control for all of the digits has been implemented (transistors in the back).
At last a fully functional clock! The display has been moved to a perfboard (Soldering that was so much fun... not). The power supply has been moved back to the breadboard and I replaced some of the components with smaller version (no more big orange cap!).
I just love this display (even in bad pictures).
Everything moved to perfboard. No alarm yet.
Alarm complete! It was kind of amusing, the speaker would draw so much power that the the display would fade while the alarm was going off. I used the arduino to generate the alarm waveform (I matched it's frequency exactly to my old alarm clock, I guess I like consistency). Then I used a transistor to drive the speaker.
After using the clock for about 6 months I decided it would be a good idea to stick it in some sort of enclosure. I replaced the speaker with a pezio buzzer to make everything fit (and to be nice to the power supply).