Sound Activated LED Kit - Electronics Mini Project

Hi friends, today we are going to build another interesting electronic circuit which is sound activated LED kit. We can use this circuit for sound indicator applications or sound to the light unit in the music application. This project is also useful for hearing-impaired people. By use of this circuit, doorbell sound or phone ring sound produces light indications and thus hearing-impaired people can also perform a particular action.

Sound Activated LEDs

This circuit requires simple electronic components which you can easily find in any electronic components shop. There are no any expensive components in its circuitry, hence it's a low-cost mini project. You can build this project for your second or third year engineering submissions. Let us build sound activated LED circuit step by step.


  1. Resistors:
    10KO: (R1)
    330KO: (R2)
    100KO: (R3, R4, R5)
    47O: (R6, R7, R8, R9)
    1.5MO: (R10, R11, R12)
    47KO: (R13, R14)

  2. LED: 5mm (LD1, LD2, LD3, LD4)

  3. Transistors: BC547 (T1, T2, T3) and BC557 (T4)

  4. Capacitor: 100nF (C1, C2, C3) and 100µF (C4)

  5. Potentiometer: 220K (RV1)

  6. MIC1

Circuit Diagram

[caption id="attachment_500" align="aligncenter" width="1047"]Sound Activated LED Sound Activated LED[/caption]


As shown in the circuit diagram of sound activated LEDs, we have used a 220K potentiometer. The sensitivity of this circuit can be varied by using this potentiometer. We have used a built-in microphone (M300) for sensing the sound waves.

Power consumption for this circuit is near around 0.5mA min./12mA max. It requires a 8 to 15V DC power supply. You can also use a 9V DC battery.

Features of Sound activated LED kit

  1. Intermediate level

  2. Power consumption: 0.5mA min./12mA max.

  3. It has adjustable sensitivity

  4. Require small area for installation

  5. low cast and effective circuitry

I hope you liked this sound activated LED Kit. Try to build your own and let me know if you found any difficulties in it. Please share your comments below. Like our facebook page and subscribe to our newsletter for future updates. Have a nice day!