Book Image

Arduino Essentials

Book Image

Arduino Essentials

Overview of this book

Table of Contents (17 chapters)
Arduino Essentials
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

An ambient light meter


For our first example using analog inputs, I'd propose that you build an ambient light meter: a device that indicates the amount of ambient light it can sense from its environment in some way and shows it in a visual manner, which is a perfect beginning for your next burglar detector.

For the purpose of this example, we will use a very interesting electronic device called a photocell or light-dependent resistor. A photocell is simply a specific type of resistor that varies the resistance it offers according to the amount of light it receives from its environment, exhibiting a photoconductive behavior, that is, lowering its resistance as the light increases and vice versa, commonly ranging between a few ohms when exposed to a bright light and up to some mega ohms when totally in darkness.

In the following picture, you can see a typical photocell and the usual schematic symbols you can find to refer to it:

A real photocell and its most common schematic symbols

Unlike any...