• Poornima Mani

Switch Basics

Updated: Aug 29, 2020

Switch, something that we say so often in our daily lives; something that allows us control devices and appliances and we can't even imagine how lives would be without it. Let us take a deeper look at what a switch does and how it works.


A switch is an electrical device that is used to connect or disconnect a circuit manually or automatically according to the need of the hour. The principle of working is simply an ON/OFF mechanism.


Fancy Switches

In a switch, there are two components called poles and throws. Poles are the number of circuits controlled by a switch whereas throws are the number of positions that a switch can take up.


Switches vary from one another depending on the number of poles and throws that are present in them. Let us see a classification of switches on this basis.


Single Pole Single Throw


This is a type that allows us to connect and disconnect a circuit. Toggle switches are usually made of this type as it has a single input and output. It works on a simple logic that when the switch is ON current flows and vice-versa.





Single Pole Double Throw


This is a three-terminal switch where one is input and the other two represent output terminals. Such a system is usually used in three-way circuits. Here, you can see that this particular circuit is wired up in two modes; one where the lamp is turned ON and the other while the LED is OFF.



Double Pole Single Throw

Such a switch has two inputs and two outputs where one corresponds to the other. Such a switch is used for multiple purposes. It is mainly used to operate 240 V devices where the two supply voltages must be turned ON and current flows through the circuit. There is usually a single toggle where control is made by a single push.


Double Pole Double Throw


This type of switch is the equivalent of two separate circuits in it. There are a few possibilities in the way the switch works. If it is in the OFF-OFF mode or the ON-ON mode, then it works as separate SPDT switches.



Other than these conventional switches, many new types can be accustomed to the need and accuracy required.


Applications and Purpose dependent switch


1. Dimmer:

This is used as a regulator to regulate fan and light in a room. It mainly changes the resistance and adjusts the intensity of the output. These are commonly used in the bathroom, kitchen, hallways, etc. There are many kinds of such switches available than can be used according to the required purpose.



2. Pushbutton Switch:


This is a mechanical switch and is prevalent in industrial control panels. Depending on the function, it is used for latching actions mainly in the field of industrial and medical applications.

Commonly seen in calculators, gaming, and machinery, they are available in various shapes and sizes.


3. Transistor as a Switch:

The transistor is an electronic component that can be configured in multiple ways. But in this article, we will focus on how it can be configured in the form of a switch.

The idea is to keep the transistor between saturation and cutoff regions. When a huge amount of current passes through it, we can push the transistor into deep saturation mode; i.e. the switch is in the ON condition.



The applications of the switch are not limited to these. Some many types and functionalities are being used these days.


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#Switch

#SPDT #DPDT #DPST

#SPST #Dimmer

#Transistor

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