Ever see a little solar dancing flowers on someones desk? This Dancing Pumpkin is the Halloween version of that little decoration. I spotted it in a store for around a dollar and it was wondering how they could make it this cheap. Watch the video to see what’s inside, not knowing their was a coil glued to the base I almost destroyed the coil while with my screwdriver while trying to pry the bottom off. Like all other mass produced items like digital watches and cheap calculators there is a mystery IC bonded directly to the tiny PCB and covered by a blob of epoxy. The construction is very simple it consists of a solar cell, a capacitor, the magic IC, a coil and a magnet.
The pumpkin dances when the pendulum with the magnet is swung back and forth. The position of the coil is slightly off center of the magnet which allows the coil to gently start pulling the magnet towards the coil with small pulses. After 5 or 6 pulses it has enough momentum to continue with a large swing. The unit works fine with as little as 500 lux and draws only 85 micro amps when in constant operation. I am very impressed that this cheaply mass produced item can swing with sufficiently low resistance to operate reliably.
