How to solve these problems when I'm designing the amplifier

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How to solve these problems when I'm designing the amplifier

Postby Bruno12 » 15 May 2017, 11:01

Hi, I'm designing an audio amplifier using LM386 and a preamplifier. And this is the circuit .


But i am still getting acoustic howling. What can I do to prevent it dynamically?
Also I want to increase the sensitivity to the extent that when I rub my fingers in front of the electret mic the speaker should be able to play it .
When I cover the speaker, the howling stops . But the sensitivity is reduced and also I think that to eliminate the mains noise I need to eliminate the ground loops .
How do I eliminate ground loop ? Also Can i use a simple op amp like 741 c to eliminate the noise where the inputs are a scaled version of the output and the preamp input
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Re: How to solve these problems when I'm designing the ampli

Postby phatt » 15 May 2017, 11:32

A bit hard to workout your layout but at a guess I'd say remove the regulator and run both the LM386 and preamp from only one battery.
The whole lot will easy fit on one breadboard. Try and keep wires as short as possible until speaker output, an maybe keep input preamp on one end off BB and LM386 on the other end will help keep things stable.
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