Darkness Detector using LDR

Darkness Detector or Dark Detector is a circuit that detects darkness or absence of light. In this project, we have implemented a simple Darkness Detector Circuit using the simplest of all light sensors: the LDR (Light Dependent Resistor).

Darkness Detector circuits like this can be used in applications where we can automatically turn on lights when it becomes dark.

In addition to the LDR, we have also used the good old 555 Timer IC in Astable Mode to generate the required square wave. There are some passive components like capacitor and resistors. We have used a Piezo Buzzer as an alarm to indicate darkness.

The aim of this simple project is to detect darkness with the help of LDR and activate the buzzer.

Components Required

To implement this project, we need the following components.

1 x 555 Timer IC

1 x LDR

1 x Piezo Buzzer

1 x 10 KΩ Resistor (1/4 Watt)

1 x 2.2 KΩ Resistor (1/4 Watt)

1 x 1 MΩ Resistor (1/4 Watt)

1 x 1 µF Electrolytic Capacitor (50V)

1 x 0.1 nF Ceramic Capacitor (Also called 100 pF with code 101)

1 x 9V Battery

1 x Mini Breadboard

Jumper Wires