Quote:
Originally Posted by jdandy
Tom.......First, how are you coming up with the 650mv measurement? Are you measuring with a DMM or an oscilloscope? Which wires are you measuring, i.e. hot to neutral, hot to ground, or neutral to ground?
It is not unusual to have some level of DC offset on AC lines in your home. This is often caused by variable speed AC motors like those found on a hair dryer and by switch mode power supplies in electronics and computers that create DC by chopping half the AC sine wave to make a pulsing DC output. This causes the other half of the sine wave, also a pulsing DC, to be back fed onto the neutral which generates heat in the cores on transformers. Under perfect conditions the neutral tap on any transformer should have zero AC or DC when referenced to ground.
650 millivolts (0.65 VDC) is not a serious problem on a AC line but ideally zero DC would be the best. You can probably reduce the DC offset on your home power by turning off (unplugging) anything with a switch mode power supply when not in use.
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Dan, I thought the issue was coming from switching power supplies and linear PSU was the way to go.