About measuring low AC voltages...

This meter ([Link: amazon.com]) measures AC and DC, but note that the lowest AC scale is ten volts full scale, while the lowest DC scale is 0.1 volts full scale. We're so used to using such meters for DC that we're not likely to have spent much time thinking about the AC voltage measurement limitation.

This comes from the fact that all (analog) meters are actually DC meters. To measure AC at high voltages, a diode can be used to simply convert "AC" to "DC." The problem is that diodes have voltage drops around 0.7 volts, so if you're measuring voltages in that range, the meter has to compensate for the non-linear voltage drop introduced by the diode. To accurately measure low AC voltages, a circuit has to be included that compensates for this. This is not cheap!