|Project by DickB||posted 01-20-2012 04:07 AM||4317 views||24 times favorited||15 comments|
This is an exposed wood gear clock project that I am working on. All of the moving parts are out in the open, so you can see everything working, but what makes it tick is a bit of a mystery to many. Unlike most pendulum clocks where the pendulum regulates the movement, in this clock the pendulum drives the movement.
The pendulum contains a rare earth magnet, and the base has a coil of wire in it. As the magnet passes the coil, an electronic circuit senses the magnet and sends a current pulse into the coil. This gives the pendulum a “kick” and keeps it moving.
Others have designed and built clocks like this, but I have developed what I believe to be a unique drive circuit. I use a microcontroller with a watch crystal reference, and compare pendulum period to the crystal reference. Then, I adjust the pulse to the coil to speed up or slow down the pendulum a bit. This makes the clock much more accurate than it otherwise would be. There is also an LED in the base that flashes red or green if the pendulum is too fast or to slow. This makes it easier and quicker to set the pendulum bob.
I’m fine-tuning the design with three clocks built and running at this time.
Here’s a video: http://youtu.be/0hvj574hrd4
-- Dick, http://www.carveshop.com