A project whose time has come, IJ. Have you tried overclocking it?
Find a 24 hour military time clock and you can measure up to 24 volts!
An associate of mine used an analog clock display with a stepper to keep track of how many phase cycles his frequency standard was gaining or losing against WWVB, the 60 kHz radio signal transmitted by NIST in the USA. It had been a large diameter wall clock and was a useful and easy to read display for its intended purpose, although its very construction was time consuming enough that it was just done for the challenge of it.
BTW, in the USA, it appears a "Heath Robinson" device is called a "Rube Goldberg machine." A complex, bizarre, convoluted mechanism designed to do something either quite simple or entirely pointless.
