Sound Operated Light Switch

Submitted by: Manu GargEL – 163-2K116th sem

Idea Of Development

The driving force behind idea of my project comes from the fact that Engineering is about harnessing to simplify our lives. So I decided to make a project “Sound Operated Light Switch” which can be useful in our daily life for a bit of home automation.

Introduction

It is a system that will control the switching off or on of light by the help of sound (claps). Many household items are now supplied with remote control handsets- all designed to encourage laziness! However, to adjust the room lighting it is usually still necessary to get up and do it manually. This is probably because the lighting was specified by the house builder, and most householders are understandably reluctant to alter it. So here we are going to develop such a lighting system that will be controlled by sound.

Clap once lights on, clap again lights off!!

Component List

IC 741 IC CD 4017 Microphone (mic) Transistor BC 547 Diode IN 4007 Resistors Capacitors LED Battery

IC 741

8 pin Operational amplifier IC

High gain

High input impedance, low output impedance

Used with feedback circuit, with gain determined by feedback network

IC CD4017

16 pin CMOS counter / divider integrated circuit with 10 outputs

Decade counters with 10 outputs

When a clock pulse is applied to it externally, its outputs become logic ‘High' and 'low' sequentially (one after the other)

Microphone

Is a transducer that uses a capacitor (or condenser) to convert acoustical energy into electrical energy

The sound waves result into electric signals that can be used to drive a circuit or device

The pin connected to the case of mic is connected to ground and the other pin gives the output

Transistor BC 547

NPN bi-polar junction Silicon transistor

Mainly used for amplification and switching purposes. It has a maximum current gain of 800

Diode IN 4007

General purpose silicon rectifier diodes

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Allow electrical current to flow in one direction only

Used to convert AC to DC

Other Components (Resisters, Capacitors, Battery, LED)

Circuit Diagram

Working Principle

Resistor R2, R3 and variable resistor VR1 adjust the sensitivity of the amplifier. Resistor R1 set the sensitivity of Mic. The amplified output pulses from IC1 passes to the input of IC2 (CD 4017). Resistor R4 keeps the input (pin14) of IC2 low so as to prevent false triggering.

IC2 is a decade counter IC which is wired as a toggle switch. That its outputs 1 and 2 (pins 2 and 3) becomes high and low when the input pin14 receives pulses. Pin4 (output4) is connected to the reset pin15 so that further counting will be inhibited. The high output from IC2 passes through the current limiter R6 to the base of switching transistor T1. When T1 conducts, White LED (D2) turns on. If a 6V 100 ohms relay is connected to the points marked (A and B), the relay will also energize and the load (bulb or electrical equipments) will be switched on. In the next clap, output pin 2 becomes low and relay and White LED will be switched off. LED D1 (Red LED) indicates the OFF position.

Advantages & Disadvantages

ADVANTAGE

Can be used to turn something (e.g. lamp, TV, radio) on and off from any location in the room simply by clapping hands

Useful for mobility-imapired person

DISADVANTAGE

Cumbersome to have to clap one's hand to turn something ON or OFF

Future Improvement Scope

We can increase the range of this equipment by using better Mic

Can modify the circuit little bit and use for security purposes

Application

Clap switch can be used to switch ON/OFF any electrical appliances such as:

Tube light Fan Television Air Conditioner Motor

THANK YOU