This is an audio amplifier with 2 LM386 integrated circuits. Basically it deals with the use of 2 amplifiers as in another article posted at a time ago. But this time it includes printed circuit board for stereo version, in addition to power supply. The circuit operates with power supply or batteries of 6 to 12 volts. The best performance will be when using a 12V power supply and 8 Ohms speakers.
The operation of the circuit is simple and based on the LM386, responsible for the amplification, the stereo audio signal is coupled by the capacitors C5 and C11, the stereo potentiometer P1, is used to adjust the volume.
The components attached to pins 1 and 8 control the gain:
- No component: Gain = 20.
- 10μF Capacitor (Jumper on R2 and R4): Gain = 200
- 10μF Capacitor and 1.5K Resistor: Gain = 50
The output is coupled via 470μF Capacitor, if you want to use with headphones add resistors from 100 to 220 Ohms 1Watt in series with the output.
Schematic of the audio amplifier LM 386 stereo
Suggested Printed Circuit Board for mounting the circuit stereo amplifier with LM386N
Part list for mounting a stereo amplifier with LM386
|Resistors 1/4 Watt 5%|
|R1||560 – Green, Blue, Brown, Gold|
|R2, R4||1K – Brown, Black, Red, Gold|
|R3, R5||10 – Brown, Black, Black, Gold|
|P1||10K – Double Potentiometer|
|C1||2200µF/ 16V – Electrolytic Capacitor|
|C2, C8, C14||100nF – (100n, 104, .1, 0.1) – Ceramic or Polyester Capacitor|
|C3, C9||100µF/ 16V – Electrolytic Capacitor|
|C4, C10||10µF/16V – Electrolytic Capacitor|
|C5, C11||4.7µF/16V – Electrolytic Capacitor|
|C6, C12||470µF/16V – Electrolytic Capacitor|
|C7, C13||47nF – (473, 47n, 0.047) – Ceramic or Polyester Capacitor|
|D1, D2, D3, D4||1N4004 Or equivalent – Semiconductor diode|
|IC1, IC2||LM386N – IC|
|LED1||Red led 5mm|
|AC||Connector for transformer|
|IN||Audio input connector|
|OUT||Audio Output Connector|
|J1||15mm piece of wire|
|TR1||6 to 9 Volts / 500mA Transformer|
|Welding, Wire, PCB, Box, Knob Potentiometer, etc.|