Posted by Circuits Arena on Sunday, 9 November 2014
CLAP SWITCH USING TRANSISTOR is the artlcle explaining Clap Switch Hobby Circuit for electronics hobbyists that can switch on & off a light, Fan, Radio etc., by the sound of clap. T...
Clap Switch
Hobby Circuit for electronics hobbyists that can switch on & off a light, Fan, Radio etc., by the sound of clap. 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 feed to the Bistable Multivibrator
circuit also known as flip-flop circuit.
Circuit is made by using two Transistor, in our circuit Q2&Q3. In a
flip-flop circuit, at a time only one transistor conduct and other
cutoff 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 makes changes to the
output state that is complementary (reverse). Output of flip-flop, which
is in the low current form is unable to drive relay so we have used a
current amplifier circuit by using Q4 that is a common emitter circuit.
Output of Q4 is connected to a Relay (Electromagnetic switch) which
works like a mechanical switch and it becomes easy for connecting other
electrical appliance.
A relay contact is connected to the power line and hence turns on/off any
electrical appliance connected all the way through relay.
Materials Required
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
Semi Conductors
Q1,Q2,Q3= BC548
D2,D3,D4= IN 4148
D1,D5=IN 4007,
Q4=BC368
Misc
T1=12v/500mA Transformer
Mic= Condenser Microphone
K1= 12V Relay, B1= Bulb or Load
