The following figure shows a typical IC LM386 amplifier circuit having the bare minimum number of components required to make the IC operate at its internally set level of gain 20. Practical Application Amplifier Circuits Using the IC LM386 The gain may be simply made adjustable by connecting a pot in series with the above explained capacitor across the pin 1 and 8.

If a capacitor is joined across the above pin outs, the gain is suddenly lifted to 200. When the above pin outs are kept unconnected to anything, the internal 1.35K resistor sets the gain of the IC to 20. Gain simply means the capacity or the amplifying level of the device up to which it is able to amplify the applied input low signal audio input. In order to make the IC better with its response, its pin#1 and 8 have been attributed with a gain control facility which may be set externally. Internal Schematic How to Control Gain for the IC LM386

IC manufactured by: National Semiconductor.

Operating Temperature: 0 to 70 degrees Celsius.

Storage Temperature: -65 degrees to +150degrees Celsius.

Let's begin the IC LM386 amplifier explanation by studying its absolute maximum ratings first, meaning the parameters which should not be exceeded while using this IC in any circuit: Technical Specifications of IC LM386 As you noted though, it is a noisy device, especially when driven well beyond it's intended gain by shunting the negative feedback path to ground.IC LM386 amplifier circuit becomes suitable for applying in small low power audio gadgets like in FM radios, door bells, telephones etc. You can 'under load' the LM386, it will happily drive a higher impedance although maybe not quite as loud. If you do the signal amplifying in a low-noise amp and keep the LM386 only as the power driver it will perform far better and should work with headphones or a loudspeaker, you get the best of both Worlds! As you noted though, it is a noisy device, especially when driven well beyond it's intended gain by shunting the negative feedback path to ground.

The LM386 is the opposite, it is optimized to deliver high current to its load so it will work better driving a low impedance. You will note it says '1K' headphones on the schematic, indicating it is designed to work into a high impedance load only. The transistor output stage can never deliver more than 9/1000 Amps (9mA) to the load because of the 1K resistor so it isn't suitable for driving a low impedance. High impedance ones (2,000 Ohms for example) need lower current but higher voltage. Low impedance ones (8 Ohms for example) need relatively high currents to drive them, they are essentially ordinary loudspeakers on a headband. It really depends on the headphone impedance.

Pengganti ic lm386