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D_Dub07 t1_j9cz02d wrote

The company I worked for had designed all of our PCBs, (printed circuit boards) using switch mode power supplies without integrated components. Essentially, we had to add the coil, capacitors, resistors, etc… to define the characteristics of the supply. It just so happened the parts we selected caused the frequency the system operated at to be in the audible range. It caused an audible hum or whine, when operating.

To alleviate our issues, we selected different values of components that in the end achieved the same output characteristics, but at a higher operating frequency to prevent the hum. Pretty minor fix and everything else was the same except for the operating frequency so the hum was gone.

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ghostfreckle611 OP t1_j9dfecx wrote

Could that be what people mean when different power supplies are better or worse for coil whine? Just different frequencies or power ratings?

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D_Dub07 t1_j9dk6z0 wrote

Yes, and other factors too of course. Physical characteristics of the components, size, shape, material composition would affect this as well. I could hear the noise quite well, since the circuit board was fairly flat and made for a good speaker surface. The power supply manufacturers have their own agendas for their designs. Power efficiency, large power output, ability to handle transients (large sudden changes in power demand). They attain these characteristics different ways, so some may have these issues because they used method A, while method B produces a similar result, but with other tradeoffs.

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ghostfreckle611 OP t1_j9duotj wrote

Oh. I see. Thanks for explaining.

Seems like more of a manufacturer “shoulda accounted for” instead of a “customer could fix if they want to” kind of thing.

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