My type 22a design is a simple modification to my type 2a design that adds an output that can be turned on and off either manually or at specific times. In the first clock of this design, this output controls the swimming motion of fake magnetic fish in an aquarium, but it could just as easily control an alarm, switched outlet, or anything else.
Click here for a copy of the instructions for setting the clock and filling it with water, in Acrobat PDF format.
Interior pictures of the clock, from top to bottom:
Top of the printed circuit board. The oddly-placed IC sockets into which the Nixies are plugged are there to correct a design flaw: originally the tubes were soldered directly to the board, straddling the two 74141 driver chips. However, I failed to take into account just how much refraction there would be in viewing the tubes through the hemispherical bowl of water: the right tube ended up not being visible at all! Shifting the tubes closer to the center gives a more reasonable viewing angle.
Bottom of circuit board. It's home made, single-sided, using the toner transfer method. It unfortunately needed a lot of jumper wires to connect the processor (a PIC16LF627A) to the driver chips.
Inside back of case, showing the mechanism that makes the fish "swim". It's a small DC motor, turning two permanent magnets via gear trains with very slightly different ratios.
The coral reef background has now been added. Parts of this were carved away to make room for the PCB and the wires going to it.
PCB installed, and all wires connected to it.
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