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craque avatar

took this to show a strange resonance on my house main AC power.

this waveform recently showed up on all my scopes such that i cannot measure things accurately. my large modular PSU seems to mostly get rid of it, but i can still see any synth waveforms "warble" as if being modulated.

switching PSUs like the one used here show the amplitude modulation clearly; the real sine wave follows the contour of the signal on the power rail. notice how it shows up when the synth PSU is off and i connect the signal ("tip") end of the scope to any of the grounded elements on the synth, and how it disappears when i put the scope on battery power (though like the non-switching PSU, you can still perceive what seems like frequency modulation if you watch closely).

this is happening though three different synth PSU manufacturers, multiple scopes, and multiple power strips, even a tripp-lite with all kinds of noise filtering. the modulation isn't audible, but has rendered my scopes useless, and i highly suspect it might be causing one of my oscillators to malfunction.

978 Feb 2015 Youtube

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