Instructables

Electronic Pendulum Made Into Brushless Motor

Picture of Electronic Pendulum Made Into Brushless Motor
Pendulum Motor a.JPG
Pendulum Motor b.JPG
Pendulum Motor c.JPG
Pendulum Motor d.JPG
Pendulum Motor f.JPG
I had built this electronic pendulum for an earlier project and decided to make it into a single pole brushless motor by doubling the length of the armature and adding magnets to both ends. After balancing the armature it worked first try. Slow running motor, abut 60 RPM and very little torque though this motor will run for weeks or months on three AA batteries. If you could use the power used to light the LED it would even run longer. Interesting project.

How it works:  as the armature rotates and one end with the magnets comes close to the coil of wire, the circuit senses the magnets and turns power on to the coil to make an electromagnet which then attracts the magnet. When the magnet passes to the center of the coil the magnet is turned off, the polarity of the coil reversed and then the coil pushs the magnets away so you get this pull then push effect which rotates the arm.
This simple electronic circuit is about one of the most interesting I have ever built and the only time consuming part is winding the coil of wire which I did by hand and took about an hour. Well worth it.

This link shows how to build this electronic driver circuithttp://www.trainelectronics.com/Pendulum/article.htm

Photo 1: Shows complete motor assembly.
Photo 2: Closeup of end of armature. I hot glued magnets to end of arm which is a piece of hollow fiberglass tube (fishing pole).
Photo 3: View of axle which is a bicycle spoke inside smaller tubing which goes through center of armature. Notice red tape which is just a counterweight so both sides of armature are balanced.
Photo 4: Close up and hand wound coil.
Photo 5: Close up and electronic circuit that drives coil and armature.
Photo 6: Circuit diagram from website that describes how to build electronic driver circuit.