Solid-State switching Circuits

Introduction:
In many operations,there is required to switch on (i.e close circuit ) or switch off (i.e open circuit) in electrical circuits or electronics circuits .In some high sensitives applications it is necessary that to switch ON or switch OFF should be very fast and but not sparking in the circuits.Because of these two major reasons , the mechanical switches can not be used in the circuits for the switching purpose .This type of switch has high inertia.Therefore its speed of operations is low.This type of switches has sparking properties at the time of conduction of switching operations.
In this fast and movable world ,very high speed of switching operations without any sparking switching devices is needed.For this purpose tube and transistor are used in the switching circuits to accomplished switching operations .Such type of switches are called electronics switches .The electronics switches are also widely used to generates non-sinusoidal wave (i.e square wave , triangular wave or saw-tooth wave ,rectangular wave).
A circuits which ,preform turn ON or turn OFF current in an electronics or electrical circuits is called a switching circuits.Actually this circuit consists of followings two parts:

1. A switch and
2. Electrical or electronics circuits.

Switch:

A switch is a devices which preform turn ON or OFF circuits in an electronics or electrical circuits.The switches can be mainly classified as the following types:

1. Mechanical switch,
2. Electronics switch and
3. Electro-mechanical switch (or relay).