For well regulated DC you wouldn't.
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Art Deco spake thus:
It sounds like your mixing up a *transformer* with a *power supply*. A transformer *always* outputs AC. A power supply (which may include a transformer) rectifies, filters, and sometimes regulates this into DC. So you'd always use an AC range to measure a transformer's voltage, but you'd use a DC range to measure a DC power supply's voltage. (There are AC power supplies too.)
-- Save the Planet Kill Yourself - motto of the Church of Euthanasia (http://www.churchofeuthanasia.org/)
OK, I meant the output from the power supply. Apologies for any confusion.
BTW as I understand it, some power supply output is only half-rectified. Is this correct?
Art Deco spake thus:
Yes, but I think all wall warts use bridge rectifiers (meaning full-wave output), since the parts are, like, about a dime each.
-- Save the Planet Kill Yourself - motto of the Church of Euthanasia (http://www.churchofeuthanasia.org/)
I had a Shure wireless mike receiver power supply last week that was supposed to output 18V that was outputting 2 V dc. It turned out the secondary windings of the transformer shorted out. Chuck
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