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Clapper Switch (Clap-On, Clap-Off)

Everybody wants a light clapper, or a way to clap on or clap off something, without having to physically get get up and flick a switch. Enter the Clap Switch!

Screenshot: Clapper Switch (Clap-On, Clap-Off)

This is the schematic for a clap switch, also known as the "Clapper". It will all you to clap on/off your lights, or just about anything else.

The circuit is made of a microphone (clap detector), an operational amplifier (op-amp) 741, a 555-timer behaving as a monostable multivibrator, a D-type flip-flop, and a relay which will allow you to switch on/off just about anything. The constructor of this kit used it to turn on and off the christmas lights - awesome!!

Full operation of the circuit is explained by the author. The gain of the input op-amp is adjustable so that the noise sensitivity can be adjusted. You will probably need to calibrate it so that it detects claps effectively in your room's environment.

Clapper Components/Parts List:

  • IC1 = 741 OP-AMP
  • IC2 = 555 Timer
  • IC3 = 4013 Dual D Flip Flop
  • Q1 = 2N222 NPN Transistor
  • ----
  • C1,C2,C3,C4 = 0.1 uF Disc
  • C5 = 47 uF Electrolytic
  • ----
  • R1,R2,R4,R5,R10 = 10,000 Ohms (10k)
  • R6 = 150,000 Ohms (150k)
  • R7,R9 = 100,000 Ohms (100k)
  • R8 = 1 MegaOhm
  • R11 = 220 Ohms
  • R3 = 100,00 Ohm Trim Pot
  • ----
  • B1 = 9 Volt DC Battery
  • K1 = SPST Reed Relay 5 Volt DC Coil
  • MIC = Electric Microphone
Alternate References:
unworthybassist says: (March 13 2008, 7:17am)

this site is awesome... it really feels great learning the wonders of the electronic world...

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