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I have a microphone receiver and a raspberry pi. I'm trying to power them using one DC jack. The receiver uses 12v and the PI uses 5v. The PI is outputting music which goes into an IN port on the receiver and the receiver is supplying the microphone audio. The receiver then has an out AUX port which will send both the microphone and music to my amp/speakers.

I'm using a step down converter to convert the 12v to 5v and then power the PI. Then a ground loop isolator to remove the noise however I am still getting a large buzzing sound. When I power the PI and receiver on their own power source all of the noise goes away.

What can I do to not have to use 2 separate power sources and have clean audio? Here is a very poorly drawn wiring diagram of my setup.enter image description here

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  • \$\begingroup\$ Can you add a picture of your setup? I suspect the cabling (specifically the grounding) of the DC/DC to be the issue. From your schematic it's hard to see the issue. \$\endgroup\$
    – S_G
    Nov 10, 2023 at 6:33

2 Answers 2

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The interference is probably not from a ground loop, but from the mic picking up EMI from the raspberry pi or the DC to DC converter. Put a inductive ferrrite cable clamp on all cables going to the mic receiver to see if it is conducted emissions (EMI going into the cables and then to the mic)

If it isn't conducted emissions, then it could be EMI/radio emitted by the PI or the DC DC converter going through the air. You would then need to shield the MIC with a faraday cage that could block radio emissions and/or move the Pi and converter away from the mic.

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To handle/attenuate the spikes from the SwitchReg, you can do this --->

First, tie the various GROUND points TOGETHER with about an INCH of stranded Wire.

This does not include the power_line ground.

Thus everything powered by that Switchreg ------ tie them together, with heavy wire, to keep the SwitchReg primary-secondary coupling spikes under control.

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