electric generator

[daleroy]

can you make a hand cranked electric generator wth a solid 10" car speaker magnet? And so can some one give me a hint on how I should go about doing this?Just a project I thought of becaus I like to resycle things and I like dynimo's so I thought maybe I could make one with my speaker magnet

[Physicsgirl]

yes. You basically need to rig it so that a conductor (e.g. a coil of wire, the more coils the better) experiences a changing field. You will then get an induced voltage in the coil which will produce an alternating current if the coil is attached to a circuit. Probably easiest to have the coil or coils fixed around the outside of the magnet and then rotate the magnet in between them (coils stay where they are, magnet spins round in the middle). If you speaker magnet is doughnut shaped, you might need to put it on a shaft so it looks like a lollipop and then find a way to make it turn, the faster the better. Hope this makes sense. You probably won't get life-changing amounts of power out of it, maybe enough to power a small (torch) bulb or similar. Depends on how many coils, how fast you turn the magnet, and so on.

[8733mags]

If you wish to discover about electricity generation, get hold of a small electric motor. Maplins have small motors for model boats etc and this is a good start. If a small DC motor is connected to a battery, the motor will rotate. The speed that it rotates at depends on the voltage from the battery. A DC motor is a very good generator. All you have to do is to connect a cycle bulb to the 2 wires from the motor and turn the motor and the bulb will light up. The brightness if the bulb is proportional to the speed of rotation. To recycle your magnet you could copy the small motor which has a magnet and inbetween the magnet there are coils that terminate in a comutator and some brushes to the terminals. Difficult to make but any interesting task....good luck