Mar 242020

Electronic sound control circuit (applause)

This electronic sound control circuit works like a sound activated relay and can activate or deactivate a device connected to it, by two consecutive claps.

Applications for this circuit can be: activation / deactivation of lamps (light bulb operated by applause), water heaters, etc.

Electronic Sound Control Circuit Operation

When a clap is detected by the microphone (MIC), the signal is transmitted to the inverting input of the operational amplifier. The op amp compares its two inputs and outputs a signal that triggers the 555 timer IC which is configured as a monostable multivibrator.

Electronic sound control Circuit (applause)

The 555’s output pulse activates the two clock inputs of the 4013 (2 D-flip-flops) integrated circuit.

The 4013 is configured as a 3-state counter, so it will take two claps before the flip-flop’s Q1 output goes high and turns on transistor Q1. Transistor Q1 in turn will activate the RLA relay. The relay works with 5v, and it is necessary to include the 220 ohm resistor in series to be able to use it with 9 volts. Diode D1 is used to protect transistor Q1.

555 timer IC Pinout

555 Timer PinOut

Pin diagram of IC 741 Op Amp

741 op amp Pinout

4013 Dual D Flip-Flop Pinout

4013 – Dual D Flip Flop Pinout

List of circuit components

  • 1 741 op amp (IC1)
  • 1 555 timer (IC2)
  • 1 4013 (Flip-Flop type D, Dual) integrated circuit (IC3)
  • 1 2N2222 NPN transistor (NTE123) (Q1)
  • 1 1N4001 diode or similar (D1)
  • 4 0.1uF capacitors (C1, C2, C3, C4)
  • 1 47uF electrolytic capacitor (C5)
  • 5 10K resistors (R1, R2, R4, R5, R10)
  • 1 15M resistor (R6)
  • 1 10M resistor (R7)
  • 1 100M resistor (R9)
  • 1 1M resistor (R8)
  • 1 220 ohm resistor (R11)
  • 1 100K potentiometer (R3)
  • 1 microphone (can be one of those used in recorders)
  • 1 5V relay (RLA)
  • 1 9 volt battery (B1)

Note: The circuit is connected to a 9 volt battery, but can be easily connected to a 12VDC source. In this case, the 5v relay is replaced by a 12v one and the 220 ohm resistor must be removed.

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