June 25, 2009


Function of a Switch

A switch is circuit element that allows or prevents the flow of electricity through a circuit, there are many types of switches they are as follows.

Single pole single throw switch

Circuit symbol

This is the most widely used switch, it can be either closed or open.

Single pole double throw switch

This is an electromagnetic switch also know as a relay, it consists of a coil that acts as an electromagnet and when the coil is powered by a source (Battery) the coil becomes a magnet and attracts the plate and the circuit gets closed and when the source is cut off the coil loses it magnetic property and a spring makes the plate to return to its original position.

Double pole single through switch
Double Pole, Single Throw switches control two circuits simultaneously. Circuits are ON at the same time, OFF at the
same time and may be of different voltages from separate sources.

The main in our house is a DPST switch both the phase and neutral poles are opened or closed at the same time

Double pole double through switch

Double Pole Double Throw switches control four circuits, permitting only two circuits to be energized at a time.

Push to break or Normally close

This switch is normally close and when pressed the circuit becomes open and when released it closes the circuit.

Push to make or Normally open

This switch is normally open and when pressed the circuit becomes closed and when released it opens the circuit.


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Electronics is the study and use of electrical that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves. and semiconductors. The pure study of such devices is considered as a branch of physics, while the design and construction electronic circuits to solve practical problems is called electronic engineering.

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