Simple UV Counterfeit-Money Detector
This simple project uses ultraviolet light to detect counterfeit $5, $10, $20, $50 and $100 US bills.
electrical
Dodecahedron Speaker for Desktop 3D Printers
At normal listening distances, an array of twelve speakers arranged on the faces of a dodecahedron is a very good approximation of a point sound source, and the sound waves it produces are very close to perfectly spherical. A dodecahedron speaker can be a useful tool in acoustics research, and is definitely a fun toy […]
Make: Compressed Air Rockets Kit
Building this rocket launcher is a breeze, and folks are always amazed at how it shoots reusable paper rockets 200–300 feet high. The launcher is made from PVC pipe. You pressurize its chamber to 75psi with about 18 strokes of a bicycle pump, then release all the pressure in a split second through an electric […]
