Quote:
Originally Posted by Nickthedentist
...or a quartz clock mechanism with the seconds hand operating an optointerruptor.
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I like this idea, because it is simple and low tech. You do actually have a master clock (albeit a battery powered quartz movement) driving the slave clock too.
Also these movements are a good way of getting accurate low cost mechanical timekeeping. I have seen them used in things like cat feeders for exactly that purpose.
An opto-interruptor (make a double-ended second hand for 30 seconds), a power transistor or relay with a bit of other electronics, and a spare power supply or battery, and it shouldn't cost more than a tenner or so. You can buy a cheap clock in Ikea, a pound shop or charity shop just for the mechanism and second hand.