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Are certain types of inductors more likely to create an audible sound than others when under use? Is there any sort of best-practice or guideline to minimize such humming or buzzing sounds? I.E. oversize (max current) the inductor or mount it on a rubber pad or similar? or perhaps an alternate format, i.e. a toroid type?
vacuum impregnated inductor were suggested by jeroen74
Toroidal types seem less prone to making noise than "rod" type ferrite inductors.
Molded inductors are probably best, followed by vacuum impregnated types. Tape wound cores also seem to be good. Loose laminations on steel core inductors can make a terrible racket.
I think most of the transformer "hum" we hear is due to magneto-stricition. (The material changes size in a magnetic field.) It only depends on the magnitude of the field so we hear the hum at 120 Hz. (here in the US.) So to reduce noise, one would have to reduce the maximum B field. I think that just means using an over-sized inductor for the job.
