Toms Online Notebook Sharing my stuff.

Something to note! If you are trying to measure a DC circuit voltage (possibly one that you have just rectified from an AC source) to see if there are any component traces of an AC signal;  Simple multi-meters probably will not give you an accurate AC reading (in AC mode) when checking the DC side of a rectification circuit.  You really need to use an oscilloscope.    I was expecting the NON-Sinusoidal ripple to be picked up/measured.

I thought that using the AC setting on my old cheap multi-meter would still give me some type of RMS or average AC reading - NOPE!  Don't be fooled.

Some good MultiMeters like Fluke, will give you TrueRMS which is an RMS reading on NON-Sinusoidal signals. (see Fluke description of TrueRMS)

See another online post at DIYAudio asking a similar Q...   https://www.diyaudio.com/community/threads/ac-voltage-after-rectification.58359

 A was troubleshooting a grounding issue.