Electronics > Projects, Designs, and Technical Stuff
Requesting advice to reduce noise in car audio PCB
SilverSolder:
Ground loops are a big issue in cars, since the chassis of the car is used not only as ground, but the negative conductor... So your DC/DC converter idea is a winner, I'd keep that in the final version.
Another solution could be to use an audio transformer to break the ground loop. You could try that today on your second design, and see if it removes the noise!
David Hess:
I have had problems with alternator whine getting into my car audio before.
Alternator whine usually is the result of a ground loop however in this case it could be caused by lower line regulation with the switching converter since that is what you changed. This is one of those cases where I might consider using a capacitance multiplier which could double as input protection for the switching regulator if improving the regulator's line regulation was not an option.
The analog and digital ground planes usually need to be connected at one point but this point might be through the connector.
maakbaas:
Thanks for all the suggestions. I understand some things better, although I am still a beginner ;)
I made a new version of the PCB, this is the first time I attempted a 4-layer design, and this time I made sure that no single trace crosses splits in power and ground planes.
I am really grateful for the comments so far, and if anyone sees any mistakes in this new version, feel free to let me know :).
I chose for my second suggestion and combined the isolated DC/DC with the switching 12V to 5V regulator. I did not take care of the comments for DC side protection yet.
Also I did not do any pours on the signal layers. Can anybody recommend a good source that discusses this? It is not fully clear to me yet if this would be advantageous or not.
Power planes:
Ground planes:
SilverSolder:
What tool are you using to create the PCB? The artwork looks pretty cool...
maakbaas:
Its Kicad. While in 3D viewer there is a menu item to enable ray tracing which improves the render (I also only found out about this today :))
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