Electromagnets #

Electromagnets describe magnetic feilds that are created by the flow of electricity through wires. Electromagnetism is at the root of many microphones and speakers as coils induce the attaction or repulsion of a magnet attached to a drum like membrane that pushes air back and forth to make sound. Many motors are also controlled by electromangets that push and pull a central shaft around a central point.

The most basic form of electromagnet is a coil made from magnet wire. To make one by hand, just grab some 28AWG magnet wire, write it around something like a pencil a few hundred times, and connect either end of the magnet wire to a 9 volt battery. Switching the polarity of the circuit (e.g. which ends of the coil are connected to the + and - side of the battery) changes the direction of a magnet field. You can test this by dangling a strong magnet (like a neodynium magnet) just over the coil on a string. You should feel the magnet attact or repel as you change the polarity of the coil.

Inspiration #

Irene Posch - The Embroidered Computer Here, coils are integrated via embroidery. The coil powers a switch, which allows the textile to function as a computational logic gate

Irene Posch & Ebru Kurbak - 1-Bit Textiles Similar to the above, coils are integrated via embroidery and a magnetic bead sits within the coil and changes its orientation in response to the magnetic field.

Nick Collins - Hardware Hacking Wonderful text with many example activities to try involving induction coals, microphones and speakers.

Nick Collins - Handmade Electronic Music Except from the Book Description: “Assuming no technical background whatsoever, the book carries the reader through a series of sound-producing electronic construction projects, from making simple contact microphones, to transforming cheap electronic toys into playable instruments, to designing circuits from scratch. Along the way, I put the technologies into historical and aesthetic context through information about, and audio and video samples by, artists who have used similar devices to make significant musical breakthroughs.”