Simple Single Channel Audio Amplifier With LM380N

Here is a simple one-channel audio amplifier made by yourself, which can be made with IC LM380N. According to the datasheet, the LM380N outputs 2.5 watts into an 8 ohm speaker at 18V. Tested the DC power supply using this project 12V.

The power source can be a 230V to 12V DC adapter or a 12V battery. But 12V because of the AC/DC adapter can cause humming. LM380N cheap 14-pin PDIP IC is readily available in the market.

ICI - LM380N Audio Amplifier

R1 - 2.2 ohms VR1, 10k ohms

C1 - 4.7µF, 35V Electrolyte

C2 - 470pF ceramic disc

C3——0.22μF ceramic chip

C4, C6 - 470μF, 35V electrolyte

C5, C7 - 0.1μF ceramic chip

CON1 - 2-pin terminal connector

CON2 - 2-pin connector

LS1 - 8 ohm, 3W speaker - Heatsink for IC1 - 12V power supply/12V battery

The circuit diagram of the audio amplifier is shown in Figure 1. A suitable pot (VR1) is connected at input pin 2 of the IC. An 8 ohm, 3 watt speaker is connected to pin 8 of the IC through a 470uF electrolytic capacitor C6. Pin 14 of the IC is connected to the positive pole of the 12V power supply.

The 4.7μF electrolytic capacitor C1 through the audio input and the volume control VR1 potentiometer enters pin 2 of IC1. IC13-7 pin is connected with 10-12 pin. Pins 9 and 13 are not connected.

Figure 2 shows the amplifier PCB and Figure 3 shows its component layout. A suitable layout Veroboard can be used instead of a PCB.

Put the Veroboard 14 pin on the middle IC socket Veroboard, and solder according to the circuit diagram. CON1 on the left, speaker LS1 on the right side of the Veroboard. On the Veroboard fix VR1 in the middle.

Connect all GND pins of IC1 to ground. You can also use a suitable heat sink for these ground pins.

To test, after installing the IC in the socket, connect an 8 ohm and 3 watt speaker to the right connector LS1. Connect a 12V battery or 12V AC/DC to the positive and negative terminals of the adapter CON1.

Keeping the volume control (VR1) blade in the middle, touch the audio input terminal with a metal screwdriver. If you hear humming from the speakers, the power amp is working.

Connect the audio of the mobile phone or laptop to the input terminal CON2 of the power amplifier. Adjust the jar VR1 until you hear pleasant and clear sound.