Our house came with this clock in the kitchen. The clock runs several hours fast per day, making it completely useless for telling time. So of course, I took it apart and messed with it.
I was hoping to find some timing adjustment inside, but the clock must have cost around 5¢ to make, leaving no room for such niceties. In the end I just figured out the gear assemblage and put it back together.
Here’s the insides:
The motor on the left is rather clever. There’s an IC on the back containing the piezo. Every second, this reverses the polarity of the attached coil, causing a magnet to flip over. This makes the ‘click’ sound in electric clocks. Unfortunately, I can’t do anything to fix a faulty IC circuit.
Gear layout. The motor drives gear 1 (omitted from photograph), which is transmitted to the second hand (3), the minute hand (5), and the hour hand (7). Gears are labeled with the number of teeth.
||Ratio to previous
One thing I was unable to figure out is the mechanism keeping the magnet flipping in a consistent direction. So as a prank/experiment I reversed the leads on the motor coil. We’ll see how long it takes my roommates to figure out that the broken clock now runs backwards.