Quote from: Roly on July 05, 2014, 04:59:39 AMQuote from: nashvillebill(merely switch the meter to AC)
Nope - we've been around this one before. Most common VOM's and DMM's will see DC as AC and give wildly inaccurate readings. Apparently some of the more expensive DMM's have a true AC input but most don't, they just peak rectify and assume no DC. To measure ripple with one of these a cap, say around 0.1-1uF, of suitable voltage rating has to be used in series with the probe to block the DC. On older moving coil multimeters this was sometimes inbuilt as a socket marked "Output" or just "Out". {the one in the multimeter to hand is 0.047uF at only 400V working}
Sorry, I forgot about the averaging meters that can measure a DC battery as AC; I'm using a true-RMS Fluke.
My old Simpson 260 analog meter did indeed have the Output connection (cap coupled) to measure AC on DC....