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Questions &/or issues related to products in the Qwiic category should be posted in this forum. To learn more about Qwiic, consider checking out our pillar page on the Qwiic system.
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By buffler
OK, will try this new forum setup.
Hooked an mp3 qwiic trigger to an sta540 kit. It produces a nice whine while not playing a track. when playing a track, the whine does not seem to be there. The qwiic is running fine from an UNO and does its tricks ok, like pause, stop, etc. (BTW, there should be a note on the instructions to use the I2C instructions by removing the _ and capitalizing the second parameter, and don't forget the parens if no argument).
If I use a separate external amp for playing from the mp3 player, works fine, so some kind of power problem?
I tried a bench power supply, and switching supply, identical whine. I also isolated the amp power with l-c filters on plus and on minus and both, identical whine.
Has anyone else tried using the wm3/sta540 pair? any suggestions? It could be a powerful pair with an uno!
Looking at the forums and seeing a lot of no answers, so hoping folding tech help into the forums might be a good idea.
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By TS-John
Greetings Buffler. Thanks for trying the SparkFun forums out.

Usually filter caps are the go-to solution for power supply noise, however, using clean & regulated power supplies should eliminate the problem. Sometime a cell phone can cause issues with audio equipment as well as power lines and even some specific ways the wiring of a house is. You could try relocating your project elsewhere and see if the issue persists.

I am going to provide a section of our comments section that could help. I think muting the amp while it is idle would be a good solution if you are willing to implement it. Using specific filters caps could potentially solve the issue, too.

Look at page 20, section 6.10 for the muting schematic: ... STA540.pdf ... 4e29000000