The basics of a Permanent DC Motor.

Below is a basic electromagnet where a battery is supplying a current to a coil of insulated wire that is

wound around an iron core. The current flowing in the wire produces a circular magnetic field around

the wire which also permeates the iron magnetizing the iron core. The iron core now becomes an

electromagnet with a North and South poles. If the batteries were reversed, the current would flow in

the opposite direction in the coil causing the induced magnetic field to reverse. See the diagram below.

ELECTROMAGNET Below is a diagram of a basic permanent DC Motor. Here the stator is a two pole permanent magnet

shown with a North and South Pole which mounted just inside the motors outer housing. In between

the two poles is a coil wrapped around an iron core making an electromagnet. This electromagnet is

designed in such a way that it must be able to rotate just inside the pole faces of the permanent

magnet. This electromagnet is called an armature and has a shaft mounted on bearings which extend

out opposite ends of the motor housing. This shaft extension is used where rotational power is needed.

In order to make the shaft spin the North pole of the electromagnet must pass in front of the North pole

of the permanent magnet and South pole of the electromagnet must pass in front of the South pole of

the permanent magnet. Like poles repel, so the coil above rotates clockwise out of the field. However,

unlike poles attract so the armature continues to rotate until the North and South Poles are almost

opposite each other when the current is reversed in the coil which reverses its poles starting the process

all over again. On the rotating shaft are two copper curved plates which are insulated from each other

and the metal shaft upon which they are mounted. This is called a commutator where each plate is

connected to one end of the coil. Two conductive brushes are connected opposite each plate which

allows a power source to be alternately connected to the armature (electromagnet).

So each time the North and South poles are just about to line up the field is reversed by the commutator

which causes continuous motor action.