Automatic Staircase Light using a PIR sensor

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Introduction

Some buildings have inhabitants who don’t use the staircase lights, and those who do must pay huge bills and, therefore, a maintenance fee. Additionally, a lot of power is wasted. However, every problem has a solution, and for this one, an automatic light could be the solution. So, in this tutorial, we are going to “Automatic Staircase Light using PIR sensor.” If there is continuous human motion within seconds in a dark setting, the motion sensor will detect it and switch on the LED light.

The circuit uses a PIR sensor to detect human motion and produce brief output pulses. With the aid of this sensor, we can automate the lighting on the stairs. The PIR sensor HC-SR501 is simple to use and comes with internal sensitivity and time delay adjustments, allowing us to achieve the desired output.

Hardware Required

S.no	Component	Value	Qty
1.	PIR Sensor	–	1
2.	Transformer	–	1
3.	Voltage Regulator IC	LM7805	1
4.	SPDT Relay	–	1
5.	NPN Transistor	SL100, BC547	1
6.	Diode	1N4007	5
7.	Electrolytic Capacitor	10uF, 100uF	1, 1
8.	Resistor	1KΩ	1
9.	Electric Bulb	230V	1
10.	AC Supply	230v	1

Circuit Diagram

automatic-staircase-light-circuit-using-pir-sensor-diagram-schematic

Working Explanation

This Automatic Staircase Light circuit is created using simple components. The HC-SR501 PIR sensor is connected with bias. Through R1 Resistor, the output terminal is wired to the switching transistor SL100. The collector of the transistor Q1 is connected to the SPDT Relay coil, which is powered when the transistor is turned on and deactivated otherwise. The IC 7805 positive DC regulator and bridge rectifier, which provide a constant 5V DC supply, are the sources of the circuit’s overall bias.

The relay’s pole terminal is connected to the AC supply’s neutral line, and the bulb is wired between the phase line and the N/O contact of the relay. A step-down transformer from 230V AC primary to 9V AC secondary is used here.