This Instructable is targeted at those just stepping into the world of electronics.
In this guide I will explain how the two main types of electronic switches work, these being relays, and transistors.
Firstly, what is an electronic switch?
An electronic switch is essentially just a switch that uses an electrical current, to turn on, usually turning off when the current is turned off. Some applications of switches can be quite inconvenient for someone to go and press a button to turn on or off, such as for the starter motor in a car, or the "turn off nuclear meltdown" button inside a nuclear reactor, or in an electronics project, a small low power device such as a receiver, must somehow power a large energy guzzling component, like the motor in a garage door opener. And others just want to control their houses with their computer's, which could never possible supply the 240v/120v mains needed to run some appliances.
This guide will include a very noob friendly explanation of the internal workings of relays and transistors. First, we will begin with the simplest one to explain, the relay!
Step 1: What is a relay
For the beginner, a relay can be a very difficult application to first understand, it was for me, i spent 3-4 days researching for a simple explanation as to how a relay works, and quite recently found myself being asked for an explanation, by a clueless noob who didn't understand.
In simple terms, a relay is a device that uses an electromagnet to mechanically pull two connections together to complete a circuit, in the exact same way your finger mechanically pushes two contacts together in a toggle switch.
A relay is used wherever a small low power device or power supply needs to switch on a much larger one, usually completely isolated from the signals power source, or at a much higher voltage than the signal could provide.
However this is usually not enough to help someone really grasp the idea of how these mysterious boxes work.
Move over to the next step for a better explanation along with an flash animation to show you how it all works.