10 Watt Audio Amplifier Circuit using LM1875

In this tutorial, we are going to make a “10 Watt Audio Amplifier Circuit”.

An audio power amplifier (or power amp) is an electronic amplifier that amplifies low-power electronic audio signals such as the signal from a radio receiver or electric guitar pickup to a level that is high enough for driving loudspeakers or headphones. Here we designed a simple 10-watt audio amplifier using IC LM1875. LM1875 is a monolithic power amplifier that provides a low distortion level even at high output power levels and large output voltage swing so that the speaker can respond well to output audio signals. It also has a high gain and fast slew rate.

The IC has five pins, can drive an 8Ω speaker and gives 10-Watt output, can deliver up to 30 watts when we use 30V bias. It has thermal protection and internal output protection diodes. It comes in a TO-220 package. This Amplifier provides internally compensated and stable operation for a gain of 10 or greater, it requires a few external components.

Hardware Components

The following components are required to make 10 Watt Audio Amplifier Circuit

S.no	Component	Value	Qty
1.	Audio amplifier IC	LM1875	1
2.	Loud Speaker	8Ω	1
3.	Variable Resistor	82KΩ,4.3KΩ, 10Ω	2,1,1
4.	Electrolyte Capacitor	4.7µF, 1000µF	1, 1, 1
5.	Connecting Wires	–	1
6.	Power supply	9V	1
7.	Ceramic Capacitor	0.1µF	1

LM1875 Pinout

10 Watt Audio Amplifier Circuit

For a detailed description of pinout, dimension features, and specifications download the datasheet of LM1875

Working Explanation

The circuit diagram of the audio amplifier is shown. It is built around the popular amplifier LM1875 (IC1), an 8-ohm, 10-watt speaker (LS1), and a few other components. IC LM1875 has only five pins, two are input terminals one is the output terminal and the remaining two are for bias. Here audio input signal is applied to the non-inverting input terminal, inverting input terminal is connected between feedback Resistor R3 and to ground supply through R2, and C1 elements.

As we expect 10 Watts audio output only hence we have connected an 8Ω loudspeaker at the output. Now Connect the audio input from your mobile/laptop/PC to a 2-pin input connector and applied +9V as a bias supply. Amplified audio output is fed into the speaker through the C3 capacitor. Finally, you can hear an amplified sound in speaker LS1.

Applications

Audio power amplifiers are found in all manner of sound systems including sound reinforcement, public address and home audio systems, theatrical and concert sound reinforcement systems, and musical instrument amplifiers like guitar amplifiers.