When we are designing Amplifier circuit we should consider the input audio source and target output device or target loud speaker specification then only we can develop efficient audio amplifier. Here the Simple Speech Amplifier Circuit designed with consideration of condenser mic audio input and 8Ω loud speaker output.
Well known Audio amplifier IC TDA7052A is used here as a main part. The TDA7052A is mono BTL output amplifier with DC Volume control and also it has the following features, Requires few external components to design full amplifier circuit, It has mute mode, thermal protection and short circuit protection, provides good overall stability for all range of signals.
- IC TDA7052A – 1
- Loud speaker 8Ω – 1
- Condenser Mic – 1
- Transistor BC547 NPN – 1
- Variable Resistor POT 20KΩ – 1
- Resistors 100KΩ, 10KΩ, 330Ω, 1KΩ – each 1
- Capacitors 1µF, 10µF, 0.1µF – each 1
Construction & Working
Before start with construction of Amplifier circuit, let us see about IC TDA7052A. It is a 8 pin dual inline package IC, it is also comes in SO8 plastic package. It gives 1 watt when we use 8Ω RL loud speaker and 6V bias.
Pin Details of IC TDA7052A
Pin 1 – VP positive supply voltage
Pin 2 – IN+ positive input
Pin 3 – GND1 signal ground
Pin 4 – VC DC volume control
Pin 5 – OUT+ positive output
Pin 6 – GND2 power ground
Pin 7 – n.c not connected
Pin 8 – OUT− negative output
Here we using Condenser mic as audio input source hence it requires pre-amplifier stage, Condenser mic receives bias through R1 Resistor and connected to the transistor base through C1 capacitor. Transistor Q1 Increases the audio signal strength received by mic. Output from Q1 is connected to Positive input pin 2 of TDA7052A through coupling capacitor C2 and Variable Resistor RV1, Here this RV1 acts as a Volume control potentiometer. Bias pins of TDA7052A are connected to 9V DC supply. 8Ω Loud speaker is connected with output pins 5 and 8.