This circuit given here can be housed in the box containing the speaker to form a handy microphone amplifier.The device can be used by teachers,guides,lecturers etc for speaking in a crowdy or noisy environment.

The circuit is designed base on the audio power amplifier IC TDA 7052.The IC can deliver a maximum power output of 1.2 W at a 6V supply.The audio signal from the microphone is pre amplified by the amplifier based on Q1 (BC 547) and give to the input of IC1 (pin 2).The POTR5  acts as a volume control.The capacitor C3 is used to bye pass the upper frequencies in order to avoid the Larsen’s effect(the microphone picking up speaker output to cause howls).

Circuit diagram with Parts list. 



  • Use a 8 Ohm speaker or two 4 Ohm speakers in series as load.
  • Assemble the circuit on a good quality PCB or common board.
  • A 6V SMF battery is my choice for powering the circuit.
  • Switch S1 can be used as a ON/OFF switch.


  1. if we attach a simple cndnsr mic(without pre-amp) at the input wl it amplify da voice spokn?plz rply m wtng.

  2. I am a class 12 student. I have a single speaker of 4 OM 6 W. I want to sound it with a mobile phone and with 220v domestic current. Will you help me to suggest which component should i purchase, and how it should be assembled .
    Thank you for help


    Please i need the power supply circuit of speech amplifier box. Thankz

  4. Aboobakal

    i want to make an amplifier so plz help with a simmple circuit

  5. plz i want to kwon the scope and features of speech amplifier box.thankz

  6. does this work properly??????????means if you say something in a low voice will it amplify and produce a large output????