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I connected a DFPlayer with a PAM8403 on pin DAC_R like this: Connection

I also added capacitor on the supply line.

Here the sound i have from the speaker: Audio graph

You can lisen here: https://www.dropbox.com/s/odw1ya0uxkn16ut/audio.mp3?dl=0

What can be the repetitive noise at the end (every .13sec or 7.7hz) and how to remove it? After the bell sound there is a a 3 sec of silent, but there is a click click click click during this time, why??

Same problem two different DFPlayer. Same problem with battery or powersupply (5v). Same problem with different amplifier. If i disconnect TX and RX will the mp3 is player, i still have noise.

AND If i connect the speaker to spk_1 or spk_2, i dont have noise!

David Blais
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  • `weird sound` ... are you referring to the bell sound? – jsotola Feb 08 '18 at 19:17
  • please describe what you expect to hear. – jsotola Feb 08 '18 at 19:21
  • It's after the bell. During the 3 sec of silent there is a click click click (not very loud). I modified my question. – David Blais Feb 08 '18 at 19:44
  • what were you thinking? ..... post something as quiet as possible, not a bell. ... the click may be there throughout. ... is the sound file on an SD card? ... maybe the click is in the original file. – jsotola Feb 08 '18 at 20:43
  • The click sound could be end of file errata, that is random data or EOF markers that you should not hear. Your setup may be too simple in that such stuff is not filtered out. If it is part of the music or voice recording, it could be time markers. –  Feb 08 '18 at 22:56

2 Answers2

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Try this connections

Important: Add R10, R9 to you circuit. Best way - use different power suply for mp3 module and ampflifier:

-for mp3 3.3V DC, -for ampflifier 5V DC

Evgeny Dementev
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Another solution. Insert small capacitors (approximately 1μF) between the outputs (DAC_R /_L) and the inputs on the amplifier.

Danny
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