The basic principle of a joystick is to convert the movement of a plastic stick into electronic information that a computer can process. This basic design consists of a joystick mounted on a plastic base with a flexible rubber casing. Directly below the joystick in the base is a circuit board. The circuit board consists of printed circuits that connect to several contact points. Ordinary wires then extend from these contacts to connect to the computer.
The printed circuits form a simple circuit (composed of smaller circuits). These circuits simply transfer current from one contact to another. When the joystick is in the middle position, that is, when you haven't pushed it to either side, all other circuits except for one are open. Because the conductors in each line are not fully connected, no current flows through the circuit.
A simple plastic button with a small metal disc is placed above each open section. When you move the joystick in either direction, it presses down on one of the buttons, causing the conductive metal disc to contact the circuit board. This closes the circuit, completing the connection between the two sections of the circuit. Once the circuit is closed, the current flows from the computer (or game console) along one line, through the printed circuit board, and back to the computer (or game console) through another line.
