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10-Watt Audio Amplifier using LM1875 Schematic Circuit Diagram

Here is a simple 10-watt audio amplifier using IC LM1875. The IC has five pins and can deliver a maximum of 18-watt output power depending upon the supply voltage and load. The author’s prototype is shown in Fig. 1.

10-Watt Audio Amplifier using LM1875 Schematic Circuit Diagram 1

Circuit and working

The circuit diagram of the audio amplifier is shown in Fig. 2. It is built around popular amplifier LM1875 (IC1), an 8-ohm, 10-watt speaker (LS1) and a few other components.
Connect the audio input from your mobile/laptop/PC to CON1. Connect 15V battery and switch on S1. You should hear amplified sound in speaker LS1.

10-Watt Audio Amplifier using LM1875 Schematic Circuit Diagram 2

Construction and testing

Use a 25-watt soldering iron for soldering LM1875 and other components. A 2-pin connector should be used for input and output connections to make the prototype safe and clean. Use a suitable heat-sink for LM1875 to prevent its overheating.

An actual-size, PCB layout for the amplifier is shown in Fig. 3 and its components layout in Fig. 4. After assembling the circuit on the PCB, enclose it in a suitable box. Fix LS1 on the rear side of the box.

10-Watt Audio Amplifier using LM1875 Schematic Circuit Diagram 3

10-Watt Audio Amplifier using LM1875 Schematic Circuit Diagram 4

For testing the circuit, connect a 6V battery to this circuit along with an 8-ohm, 10-watt speaker.

Take a metal screwdriver and gently touch at the input terminal. If your prototype is working, you will hear a humming sound from the speaker. You may connect a 100-kilo-ohm potmeter between audio input and ground and middle pin of potmeter to pin 1 for volume control. Your circuit is now ready to use.

10-Watt Audio Amplifier using LM1875 Schematic Circuit Diagram 5

You can use the power supply from a 5V to 15V battery, which will give you clear and noise-free audio signal output.

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