A tutorial on How to make a Light Sensor / Darkness detector circuit on breadboard using LDR and a transistor. This circuit can be used to automatically control and turn on-off lights or any loads depending on the brightness of ambient light, by adding a relay at the output. In this quickstart guide, you'll learn how to connect a photoresistor to an Arduino board and read out the voltage. The light sensor used in this tutorial is a photoresistor, which is also called light-dependent. This tutorial is a comprehensive, practical guide to the LM393 Light Detection Sensor Module (Leobot Product #222). a. This blog is based on the LDR sensor module | How LDR Sensor Works | How to make an LDR sensor module. Here we will discuss the Introduction to LDR sensor module or Photo-resistor sensor, Pin Diagram, Module Hardware Overview, Sensor module Circuit Diagram, Working Principle, its Specifications. In this tutorial, we will explore how to detect light using an Arduino.