Conversion from Vibration to Voice Currents.
The figure illustrates a simple machine adapted to translate motion of a diaphragm into an alternating electrical current. The device is merely one form of magneto telephone chosen to illustrate the point of immediate conversion.
1 is a diaphragm adapted to vibrate in response to the sounds reaching it.
2 is a permanent magnet and
3 is its armature. The armature is in contact with one pole of the permanent magnet and nearly in contact with the other. The effort of the armature to touch the pole it nearly touches places the diaphragm under tension. The free arm of the magnet is surrounded by a coil
4, whose ends extend to form the line.