Poorly shielded inductors in switch mode PSUs/old CRTs for me (Very common in older devices, low current causes the switching frequency to drop into the audible range.)
You can build your own tinnitus inducer with a cheapo 100kHz buck ic, put an air coil inductor on it, and then decrease the current until failure.
Poorly shielded electronic devices go
BRRRRRRRRRRRRRRRRRRRRRRRRRRTEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE!Poorly shielded inductors in switch mode PSUs/old CRTs for me (Very common in older devices, low current causes the switching frequency to drop into the audible range.)
You can build your own tinnitus inducer with a cheapo 100kHz buck ic, put an air coil inductor on it, and then decrease the current until failure.