LM386-Noise through switch

Other Hardware General Electronics
1

I made the standard 20 gain with volume control circuit that can be found on
the TI data sheet. I've tested a few different values and types of capacitors
and I've settled on a few that I believe are the best fit.

When I run the power directly into the power rails on the breadboard the sound
quality is as good as it is going to get given the quality of the parts I am using.

However, I have setup a 3 terminal switch where one terminal is inactive.
(power to middle, and the Amp circuit on one of the outer terminals) when I
rewire the circuit through this switch there is all kinds of noise created through
the speaker.

When I change the electrolytic capacitor to a lower value(from 1000uF to 100uf)
the sound quality improves sightly but the volume decreases.

Is there a way to use the 1000uF capacitor and filter the noise? could it be the poor
quality of the switch? I'm relatively new to all of this so a layman's description of the
problem would really help.

Thank you.

2

The figures in the datasheets are not always a complete schematic.

I'm assuming when you say "switch" you are referring to a mechanical switch (i.e. a toggle or some sort).

  1. if the addition of a switch suddenly starts creating noise then the switch or wiring is bad.

  2. you should have a capacitor from Pin 6 to Pin 4. I would suggest at least 1000µf + a 0.1µf

3

Are you using a voltage regulator?

4

Hi,

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks.. Tom... :slight_smile: