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LM386 speaker amplifier box

Bench build · Op-amps and analog ICs · Intermediate · about 40 minutes

Small amplifier for a phone or radio. Plug in a phone or radio: the volume pot sets the level into an LM386, which drives an 8 Ω speaker through a 220 µF capacitor (its output sits at half the supply). With pins 1 and 8 open the gain is 20; a 9 V battery lasts many hours at moderate volume.

LM386 speaker amplifier box: the finished build running on the simulator's bench

Build it in the labGuided build, test sheet and fault finding, free in your browser.

Parts list

Test procedure

Each test has an expected value and a pass range, like a factory test sheet:

  1. Gain at 1 kHz
  2. Idle current, no signal

How it works

What it does: Small amplifier for a phone or radio.

Build it (guided or ready-made), then run its test procedure below. Every test has an expected value and a pass range, just like a factory test sheet.

Background

Kits, intercoms, guitar practice amps and talking toys since 1980.