I made this clock around 1980. It is now the main clock in our
living room. The xylophone is an old children's xylophone. When it plays,
solenoids pull and throw small metal rods on the metal bars from below.
My clock plays a new tune every hour. There are currently 22 tunes, so
they do not repeat at the same hour every day. After each tune, two tones
are played in succession (not included on the sound sample). These
tones constitute a third interval at three o'clock, a fifth at five, an
octave at eight etc.
The hands of the clock are also driven by solenoids pulling metal
rods which in turn operate on cogwheels with 60 tans. There is an interesting
water filled shock absorber that reduces noise and makes the operation
The clock is operated by electronics. A microcontroller keeps the
time and operates the solenoids, both for music playing and hand movement.