30-07-2012, 01:32 PM
CLAP SWITCH
CLAP SWITCH.docx (Size: 102.63 KB / Downloads: 53)
INTRODUCTION
This is a project on CLAP SWITCH which can switch on/off any electrical circuit by the sound of the clap.
The basic idea of clap switch is that the electric microphone picks up the sound of your claps, coughs, and the sound of that book knocked off the table. It produces a small electrical signal which is amplified by the succeeding transistor stage. Two transistors cross connected as a bistable multivibrator change state at each signal. One of these transistors drives a heavier transistor which controls a lamp.
This circuit is constructed using basic electronic components like resistors, transistors, relay, transformer, capacitors. This circuit turns ‘ON’ light for the first clap. The light turns ON till the next clap. For the next clap the light turns OFF. This circuit works with 12V voltage .Therefore a step-down transformer 12V/300mA is employed.
This working of this circuit is based on amplifying nature of the transistor, switching nature of transistor, relay as an electronic switch .Basically, this is a Sound operated switch.
WORKING PRINCIPLE
The sound of clap is received by a small microphone that is shown biased by resistor R1 in the circuit. The microphone changes sound wave in to electrical wave which is further amplified by Q1.Transistor Q1 is used as common emitter circuit to amplify weak signals received by the microphone. Amplified output from the collector of transistor Q1 is then feed to the Bistable Multivibrator circuit also known as flip-flop.
Flip flop circuit is made by using 2 Transistor, in our circuit Q2&Q3. In a flip-flop circuit, at a time only one transistor conduct and other cut off and when it gets a trigger pulse from outside source then first transistor is cutoff and 2nd transistor conducts. Thus output of transistor is either logic-0 or logic-1 and it remains in one state 0 or 1 until it gets trigger pulse from outer source.
The pulse of clap which is a trigger for flip-flop which makes changes to the output which is complementary (reverse). Output of flip-flop which is in the low current form is unable to drive relay directly so we have used a current amplifier circuit by using Q4 which is a common emitter circuit. Output of Q4 is connected to a Relay (Electromagnetic switch), works like a mechanical switch. With the help of a relay it is easy for connecting other electrical appliance.
The relay contact is connected to the power line and hence turns on/off any electrical appliance connected all the way through relay.
COMPONENT LIST
Resistors
R1= 15KΩ,
R5, R6= 1.5KΩ
R2, R11, R12= 2.2MΩ,
R13= 2.2KΩ
R3= 270KΩ,
R4= 3.3KΩ
R7, R8= 10KΩ,
R9, R10= 27KΩ
Capacitors
C1=1000µf/16v
C2=.01µf,
C3, C4=.047µf
Semiconductor
Q1, Q2, Q3= BC548
Q4= BC368
D2, D3, D4= IN 4148
D1, D5= IN 4007,
Misc
T1= 12v/500mA Transformer
Mic= Condenser Microphone
K1= 12V Relay, B1= Bulb or Load
ADVANTAGE
• It’s used to turn something (e.g. a lamp) on and off from any location in the room (e.g. while lying in bed) simply by clapping your hands.
• It involves an elderly.
• Also involves mobility-impaired person.
• It’s also used for a light, television, radio, or similar electronic device that the person will want to turn on/off from bed.
DISADVANTAGE
• It cumbersome to have to clap one's hands to turn something ON or OFF
• Also, generally seen as simpler for most use cases to use a traditional light switch.
• Unnecessary disturbances may occur while using in the Apartments
FUTURE SCOPE
• We can increase the range of this equipment by using better Mic.
• We can use this as Remote Controller.
APPLICATIONS
Clap switch can be used to switch ON/OFF any electrical appliances such as
• Tube Light,
• Fan,
• Television,
• Air conditioner,
• Motor, etc.