Automatic Staircase Light using PIR sensor

Last Updated on March 16, 2024

Staircase lights are needed only when we walk through it other wise we don’t need it (Most useful data B-) ), traditional way is using two way switch to control the staircase light. Here Automatic Staircase Light using PIR sensor Circuit designed to make it automatic.

So we don’t manually turn ON/OFF the light, here is a simple and best solution to go Automatic!

The PIR (Passive InfraRed sensor)  detects the motion of person and gives short duration pulse output with the help of this sensor we can make the staircase light as Automatic one. The PIR sensor HC-SR501 is easy to use and comes with three standard pins (Vcc, out, Gnd) and also it has onboard sensitivity adjust and Time delay adjust, hence we can get desired output from PIR sensor.

By using Jumper setting we can change the PIR sensor mode between H: Repeat trigger mode or L: Single trigger mode.

Circuit diagram

Construction and Working

This circuit diagram constructed by using simple and easily available components. The PIR sensor HC-SR501 connected with bias and output terminal is connected to the switching transistor SL100 through R1 Resistor. The SPDT (Single Pole Double Throw) Relay coil is connected between Vcc and Q1 transistor’s collector, when the transistor ON then relay gets energized otherwise relay stay opened. Bias for the whole circuit is comes from bridge rectifier and IC 7805 positive DC regulator, it gives constant 5V DC supply.

The bulb is connected between phase line and relay N/O contact, the Pole terminal of relay is connected to the Neutral line of AC supply. Here 230V AC primary to 9V AC 500mA secondary stepdown transformer is used.

PIR sensor takes some duration to become stabilize during that time output changes randomly for about 10 to 50 seconds then becomes normal and starts sense motion.

Prototype

Here is the example prototype given, fix PIR sensor plastic cap faced towards the staircase steps, and then check the output & change time delay depends on the requirement of light duration then fix it, now your stair case light becomes automatic.