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).

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

Start clock simulation
JavaScript required, uses your computer's clock.

Push switch down Push switch up
The paddle switch at the right of the rear panel is mainly used for setting the clock, but can also select one of two alternate displays.

Stop clock simulation
This will free up the memory and CPU time taken by the animation.

Normal display mode:
Display mode when switch pushed up:
Display mode when switch pushed down:
Display options:
Digit display time: / 120 of a second
Gap betwen digits: / 120 of a second
*Dekatron mode during AM hours:
*Dekatron mode during PM hours:
*Note: the Dekatron mode settings are for reference only, they have no effect in this simulation. The animated image of the Dekatron tube is roughly equivalent to mode 18. Unfortunately, some browsers stop this animation when you start the simulation, which rather spoils the effect.

Here is the inside of the #2 clock.

Contact

Any questions or comments about this page can be directed to Jason Harper.

Normal display mode:
Display mode when switch pushed up:
Display mode when switch pushed down:
Display options:
Digit display time:	/ 120 of a second
Gap betwen digits:	/ 120 of a second
*Dekatron mode during AM hours:
*Dekatron mode during PM hours: