>        I got an "old" Digital Multimeter (DMM) that can measure ACV.
>
>        When I measure the ACV (with my old Multimeter) from the wall I
>read 110V
>or      220V (depending where I Use the Probe tips.)
>
>        So, I purchase a new DMM and in the box says: "TRUE RMS".
>
>        So I believe that ALL the DMM( the old ones and the new ones) that can
>measure ACV made it in RMS.     Is that true?
>
>        Something strange to me is that I got a Transformer: 110ACV to
>26ACV. In
>old DMM (in the ACV feature) I read 26acv but with the new one I read 1.6V
>!!!.
>
>        What«s happening with it?  Somebody can clear my confusion?
>
>        Is my new multimeter bad (defective).
>
>        Please to somebody that can helop me out.
>
>        Thanks


"True" RMS is like "Absolute" Zero: an ideal that can only be approached.
If you're making coarse measurements of nicely sinusoidal
power-line-frequency voltages, most meters should agree pretty well. Where
it makes the most difference is when you're trying to precisely measure a
waveform that has a high crest factor, i.e., a high ratio of peak voltage
to RMS voltage. Stuff like nasty HF switching power supply waveforms and
the like. Mostly measurements where you'd be better off using a scope
anyway.

I don't know about your transformer numbers, though. They don't make a
whole lot of sense. Put the two sets of meter leads in parallel and measure
it again. Make sure you're on the right scale. Add a load of say, 1K and
see if that changes the readings.

Reg Neale