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Audio Source Switching

Braeden Hamson

Feb 18, 2016
234
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Feb 18, 2016
Messages
234
Hello,

I've been having a pretty persistent problem switching between two audio sources, one is a generic bluetooth radio from amazon, the other is an Adafruit Soundboard FX https://www.adafruit.com/product/2220

I'm using a Maxim Integrated source selector chip https://www.digikey.com/en/products/detail/maxim-integrated/MAX4525LEUB-T/2045105

upload_2022-8-4_14-41-2.png

This is part of a larger circuit, however the rest of the circuit doesn't involve the audio portions. Act here, is from the soundboard its the activity indicator on the soundboard and changes the source when the soundboard plays a sound.

The issue is there is sometimes cross talk between channels, for instance the bluetooth audio can be heard when the soundboard is playing audio. There's also a significant amount of electrical noise even though I'm using isolated power supplies, isolated grounds for the audio portions and capacitors between audio and digital signals.

My question is what is the proper way to swap between audio sources using an electrical signal.

Also, here is the full circuit if it helps.

upload_2022-8-4_14-51-15.png
 

kellys_eye

Jun 25, 2010
4,775
Joined
Jun 25, 2010
Messages
4,775
What does the datasheet for the device state? Does it indicate the crosstalk figures? It should. The datasheet (which may also have application data added or made available via the manufacturers website) will detail grounding and supply separation/isolation issues if there are any. Often PCB layout/design is a major failing when it comes to noise. Is yours a breadboard design at the moment?

Either way, if your design follows the datasheet recommendations/specs then it will work as it is designed to work.
 

kellys_eye

Jun 25, 2010
4,775
Joined
Jun 25, 2010
Messages
4,775
Try a cleaner supply to start with. Use batteries if you don't have a linear regulated supply. SMPS devices are notorious for injecting noise.
 
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