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Sound Controlled Toggle Switch

Here is a simple toggle switch that can be operated through sound signals such as whistle or clap. The output of the toggle remains either low or high until the microphone senses the next sound signal. The circuit is too sensitive and can be used to control AC loads through the relay.

The sound signal received by the condenser mic will be amplified by IC1. TL071 is the high gain Operational Amplifier used in the preamplifier section of radio and tape recorder. The amplified output is used to control the JK Flip Flop IC CD4027 designed in the toggle mode. When the clock input pin 14 of IC2 gets a low to high pulse from IC1, its output turns high and remains as such. When the next pulse arrives, the output of IC2 turns low. In this way it functions as a toggle switch. Variable resistor VR adjusts the sensitivity of MIC at the particular sound level. Relay driver T1 can be used to operate the relay.

Sound Controlled Toggle Switch

7 Comments

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  • aniltvmin

    Dear mr.Mohan,

    If you have tested the circuit, pls reply to the comment.

  • kamal

    sir i have worked on this circuit but it is not working properly . is the vr 1k is apt or how to gain the sensitivity of the mic if i connect ground with tlo71 pin 2 the n it flips but it doesn’t flop next time that means the mic had no work here.

  • fred

    hello guys i’m getting confused, from what i know sound is a time varying signal so if some one gives sound will generate continuos pulses expecting the JK flip flop to toggle more than once(cause flashing) so how does the JK manage to keep its output constant until the next sound(pulse) is given,plz, and if there is any link where i can read more i will appreciate it

  • pranati

    hi i have to do this circuit plz send me tis is right or worng

  • kamal

    dear sir ,can you please tel me how to toggle a motor in reverse and forward by this circuit.

  • kamal

    dear mohan sir,i am confused of the last coment.will this circuit work?

  • Pentaconto

    I thing this circuit is not correct:

    The explanation say “The output of the toggle remains either low or high until the microphone senses THE NEXT SOUND SIGNAL”, and “When the clock input pin 14 of IC2 gets a low to high pulse from IC1, its output turns high and remains as such. When the next pulse arrives, the output of IC2 turns low.”.

    At the input pin 14 of IC2 the pulses delivered for the IC1 output are the semiwaves (positives and negatives) of sound signal sensed for the microphone. If the sound sensed is a 1000 Hz tone, the input pin 14 of IC2 were switched 1000 turns every second, and the JK Flip Flop IC CD4027 were switched 500 turns every second… The final state of the JK Flip Flop output (and therefore the relay state) only be depend of the frequency and the long of the sound sensed for the microphone.

    Greetings from Barcelona (Spain)

    (an sorry for my bad english)

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