SparkFun Forums 

Where electronics enthusiasts find answers.

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.
User avatar
By buffler
#202395
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.
User avatar
By TS-John
#202405
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:
https://www.sparkfun.com/datasheets/Com ... STA540.pdf

https://www.sparkfun.com/products/9612# ... 4e29000000