Sound operated flip flop.

john November 18, 2011 6 Comments


Here given is a circuit in which the status of the output pins of a Flip Flop IC can be toggled by using sound. A condenser microphone is used for picking up the sound. The first two op-amps in the IC1 LM 324 is used to amplify the sound picked by the condenser microphone. The third op-amp inside LM 324 is wired as a level detector. When ever the voltage produced due to sound have a level more than that of the reference voltage at pin 5 of the third op-amp, its output (pin 7) goes high, triggering the flip flop IC1 CD 4027.As a result the state of the output pins of CD 4027 ( pin 1 & pin 2) toggles for each burst of sound.

Circuit diagram with Parts list.



  • Assemble the circuit on a good quality PCB.
  • The circuit can be powered from three 1.5 V cells in series.
  • The ICs must be mounted on holders.
  • All capacitors must be rated 10V.
  • The mic M1 is a condenser mic.
  • The sensitivity of the circuit can be adjusted by varying the preset R9.
  • Prasenjit roy
    February 9, 2018

    What will be the output of Q and Q(bar)

  • December 14, 2014

    how do i make the connections for Q and Q(bar)?

  • May 20, 2013

    how many leds can hold and how should be connected

  • Apoorva
    August 1, 2012

    Can I get the project report of this project.I am interested in doing this project

  • January 8, 2012

    this will hold output the value for next sound ….?

  • vijay
    February 21, 2009

    thanks for ur cooperation and encouragements i’ll
    very happy about this site thanks

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