A clock which ticks at random, yet keeps perfect time.
We start with a cheap quartz clock (£2.47 from Argos). A cheap clock has a loud and rattly tick, perfect for this application.
The movement comes apart easily. Little plastic cogs fall out.
The rotor is a little toroidal magnet. The coil is driven with 25mS pulses, one per second, in alternate directions.
By this board, which we desolder and discard (well, lose on the bench).
Wire the coil to a couple of pins on an Arduino Nano:
Careful strain relief is required:
And put it all back together:
A little bit of code makes it go, driving the coil in alternate directions for a pulse once a second. The pulse length had to increase to get a reliable tick, and I found my cheap Nano clock ran slow by exactly 1024/1000. An accident in the crystal-specification department, I presume, which was easily fixed with a software tweak.
A new face makes it look a bit more finished (thanks to The Woodshop for downloadable clock face SVGs).
Here are the Arduino source code and face graphics. You'll also need the Arduino development tools, and an Arduino Nano or compatible. Here's a typical example from DealExtreme. I used a spare phone charger with a min-USB connector as a power supply.
The only wiring required is to connect the clock coil to pins 2 and 3 of the Nano. I used a bit of header strip to make it unpluggable, but you could solder straight onto the Nano pins if you want.Home | Artefacts| Robots