LM386 Amplifier IC
The LM386 is an operational amplifier than has been specifically designed for use in audio applications. which means its performance is based on the assumption that it will be driving speakers.
It has a default gain of 20x - meaning it will multiply the voltage it receives on the input by 20 times, passing this through to the output. The gain value can be adjusted up to 200x if needed.
Pin Description
Pins 1 and 8 - Gain: Used to adjust the gain level from the default 20x using specific values of connected capacitors.
Pin 2 - Trigger
Pin 3 - Positive Input
Pins 2 and 3 are the standard op-amp inputs. Typically in a simple LM386 circuit, the trigger will usually be tied to ground while the positive input will receive the audio signal from the source.
Pin 4 - GND
Pin 5 - Voltage Out: This pin is op-amp output, the amplified signal which we send on to the speaker.
Pin 6 - Voltage in: The Voltage Supply pin receives the power required to operate the amplifier.
Pin 7 - Bypass: This pin provides direct access to the signal input, primarily used to remove power supply noise (preventing noise from being amplified).