Continuing on the "Hangell" switching bench power supply I received a few weeks ago...

I mentioned there was some switching noise visible on the output - not a lot, but more than I'd ideally want. Today I built a filter for its outputs, with a large-ish common-mode inductor/choke rated 10 mH (accurate enough, though my meter says it drops to about half that at 100 kHz) sandwiched between a couple of 1 μF class X2 safety capacitors.

It seems to have done the trick. Under a moderate load, all the random hash has disappeared, leaving only some spikes at the switching frequency, and those are much smaller than they were before. The RMS noise value is now (barely) under 1 mV, if you believe my cheapish oscilloscope.

Like a lot of switching supplies, there's a lot of open space in the chassis, so I had room to squeeze the filter inside. I'm pretty happy with it!

Now to see if this no-brand thing works for any length of time.

#YumCha #SMPS #PowerSupply #SwitchModeSupply #Hangell #bench #workbench #noise #filter #electronics #hobby