Intro: The Little (Invisible) Drummer Boy--Santa's Shop 2016
This drum plays by itself with magic (magnetic) sticks. It is part of Santa's Shop 2016, a Christmas display that is under construction.
To build this drum, there are several 3d printed parts, two electromagnets, an Arduino and a couple of magnets.
One Arduino Uno
Twelve volt dc power supply (.7 amps or higher)
Two 2n3904 transistors
Two 100 ohm resistors
Two 1n4004 diodes
One 9 volt dc power supply (for Arduino)
Insert the electromagnets inside the drum. Be sure they are a snug fit--use tape around the outside if needed to keep them tightly in their holes.
Insert a magnet in the end of a drumstick. Glue the magnet inside or (with a soldering iron) melt the end of the stick to seal the magnet inside.
Place one end of the "axle" on the drumstick into the hole on the stick holder. Insert the other end into the small printed "bearing piece." Glue or melt the "bearing piece" to the stick holder.
Energize the electromagnet. If the drumstick is attracted to the energized electromagnet, reverse the polarity of the wires going to the electromagnet. Find the spot where the repelling forces are greatest and drill holes to mount the drumstick so that it will stay in that position.
Repeat for the other stick. Wire the circuitry as shown in step number one and install the Arduino sketch.
Paint to make it more interesting!