Manually Operated Switched

Manually operated switches are controlled by hand. These include toggle switches, push button switches, knife switches, and selector switches. Push button switches are the most common form of
manual control. A push button operates by opening or closing contacts when pressed. Image shows commonly used types of push button switches which include:

• Normally open (NO) push button , which makes a circuit when it is pressed and returns to its open position when the button is released.
• Normally closed (NC) push button, which opens the circuit when it is pressed and returns to the closed position when the button is released.
• Break-before-make push button in which the top section contacts are NC and the bottom section contacts are NO. When the button is pressed, the top contacts open before the bottom contacts are closed.

The selector switch is another common manually operated switch. The main difference between a push button and selector switch is the operator mechanism. A selector switch operator is rotated (instead of pushed) to open and close contacts of the attached contact block.
Image shows a three-position selector switch. Switch positions are established by turning the operator knob right or left. Selector switches may have two or more selector positions, with either maintained contact position or spring return to give momentary contact operation.

Dual in-line package (DIP) switches are small switch assemblies designed for mounting on printed circuit board modules ( Figure 6-12 ). The pins or terminals on the bottom of the DIP switch are the same size and spacing as an integrated circuit (IC) chip. The individual switches may be of the toggle, rocker, or slide kind. DIP switches use binary (on/off) settings to set the parameters for a particular module. For example, the input voltage range on a particular input module may be selected by means of DIP switches located on the back of the module.