This is an extension of my Nixie type 2a design to also include one Dekatron tube. The Dekatron can be set to spin in either direction at rates from 4 times a second to once per minute, jump around randomly, or display a pendulum with three possible amplitudes. The mode is settable separately for AM and PM hours, so for example the direction of spin could be used as an AM/PM indicator if desired.

The first clock of this design was a commissioned work, so I didn't bother to create my usual animated version.

Click here for a copy of the instructions for setting the clock, in Acrobat PDF format.

The design is based on a PIC16LF627 microcontroller running at 4 MHz, using 898 words of program memory and about 47 bytes of RAM.

There wasn't room in #1's enclosure for the power supply (which is more complicated than usual due to the different voltage requirements of Nixies and Dekatrons), so that was placed in a separate AC adaptor enclosure.

One significant difference from my previous clocks is that I had a printed circuit board professionally made (by Olimex), rather than hand-wiring everything on perfboard. This made assembling the clock much less tedious, and the results much nicer looking: I will probably be doing the same for many of my future clocks.

Actually, I had two of the PCBs made - the design fit in half of Olimex's minimum order size. It was several months before I got around to doing anything with the second board...

Here is the #2 clock, basically identical to #1 except for the case style. Click here for a copy of the instruction sheet (references to left/right switches have been changed to up/down, it is otherwise the same as #1's instructions).

JavaScript animated clock mockup
Here's a mockup of what the #2 clock actually looks like in operation.