Super-Freq

LM386 Gain

I’ve playing around with the 386 Audio Amplifier. This is a really great chip. It has a lot of possibilities. Looking at all of the great circuits that use this I’ve noticed there are many different ways to set the gain.

Gain is set using pins 1 and 8. With these two pins open the Gain is 20. Connecting these pins, in any of the various ways, you get gains from 20 to 200. Or at least this what I think from reading the datasheet.

The image below shows 6 different methods I have encountered for setting the gain. The datasheet suggests method 2. Many projects use method 3. The datasheet suggests using method 2 and attenuating the input to create variable gain. Which I haven’t shown here.

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2 responses to “LM386 Gain”

  1. kev Avatar
    kev

    oooh… did you figure out how to get a higher gain in #4? do tell. what did you come up with?

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  2. admin Avatar
    admin

    I think pin 1 to ground directs the feedback loop to ground which decreases the feedback even more for more gain. A few effects use this method. When you connect pins 1 and 8 you bypass an internal resistor. But there is still another resistor in the loop. When you connect pin 1 to ground some of the feedback current is shunted to ground.

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