- Mar 1, 2018
- Gold Coast, Quuensland, Australia
but in several places adding a DC blocking filter did fix some transformer hum. I've forgotten the details, but IIRC the magnitude of common-mode offset needed to induce hum in a toroidal transformer was a lot less than I expected (led to me doing a little more research to find out why).
Don't have a schematic, but it is very effective at killing toroid hum/buzz and even is effective on some marginally noisy EI transformer primaries.
Our mains waveform here is terrible looking on my DSO, makes me think we should all be locally regenerating our own.