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Audio Amplifiers

LM386

The LM386 is an integrated circuit containing a low-voltage audio power amplifier. It is suitable for battery-powered devices such as radios, guitar amplifiers, and hobby electronics projects. The IC consists of an 8-pin dual in-line package (DIP-8) and can output 0.25 to 1 watts of power, depending on the model, using a 9-volt power supply.

The LM386N-1
The LM386N-1

Models

There are three different models of the LM386 that have slightly different specifications, outlined below.

Chip
name
Supply voltage [V] Output power [mW] Load
impedance [Ω]
Min. Max. Min. Typical
LM386N-1 4 12 250 325 8
LM386N-3 4 12 500 700 8
LM386N-4 5 18 700 1000 32

Almost identical versions of the device are available from Unisonic (Unisonic Technologies Co. or UTC) as the LM386 and the New Japan Radio Co. Ltd. (JRC) as the NJM386 and NJM386B.

The JRC devices are also available in a single-in-line package.

JRC devices, marked as 386 JRC, are sometimes misleadingly referred to as the JRC386.

SPICE simulation models

Although National Semiconductor and Texas Instruments (who bought Nat Semi in 2011) do not provide an official SPICE model for the LM386, there are two independently developed models freely available:

Usage in guitar amplifiers

  • The LM386 is one of the most common amps used in DIY guitar preamplifiers and sustainers due to its ability to run on a single 9V battery.
  • The EasyEDA "Tesseract" Guitar Practice Amplifier is a versatile design based on the LM386 and features distortion and full-wave rectification effects.
  • The well-known "Smokey Amp" created by Bruce Zinky uses an LM386 and is notable for being able to fit in a cigarette package.
  • The "Little Gem" and "Little Gem MkII" are modified/cloned versions of the "Smokey Amp".
  • The "Ruby" amp is a modified version of a Little Gem amplifier.

Usage in amateur radio

The LM386 is very commonly used in the audio amplifier of low power QRP amateur radio rigs, like the Pixie.

Typical audio amplifier

Audio amplifier with gain of 20
Audio amplifier with gain of 20

  • Voltage gain is internally set to 20.


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Source: Wikipedia, LM386.
Useful links: Data Sheet (National Semiconductor) (pdf).

Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply.