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My circuit is almost identical to the Wikipedia but with 5V in, 1pF cap, 4 pieces of IN4004 diodes. I am not certain whether it is AC or DC here and there (actually I do but not want to break my multimeter). Is there some safe way to test its type? My multimeter has only separate modes for AC and DC but not a common mode for both of them. So how to find out unknown voltage type?

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  • \$\begingroup\$ Are you referring to voltage here? The wikipedia article's circuit assumes AC voltage, as this rectifier circuit 'converts' ac to dc voltage. \$\endgroup\$
    – pfyon
    Jun 9 '10 at 3:36
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If you set your multimeter to DC(V) and then measure an AC(V) it will not cause damage, neither will the opposite.

If you measure it with both, and one says 5 V, then that is what signal you have. 5V AC wave will not be anything on DC measurement, but will be 5V with AC turned on.

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    \$\begingroup\$ as a side note, if they mean 5VAC rms, which often is the case, then the actual wave is going to be 5V*squareroot(2) in magnitude. \$\endgroup\$
    – Kortuk
    Jun 9 '10 at 19:36
  • \$\begingroup\$ This is true if the waveform is a sinusoid. If the waveform is something else (e.g. squarewave or triangle or highly distorted), then the sqrt(2) factor isn't correct. Furthermore, one also has to be careful about the meter -- true RMS meters actually compute an RMS value and will give "correct" readings for non-sinewaves. Lower cost ac meters assume a sinewave and just apply to 1/sqrt(2) factor to the peak. \$\endgroup\$ Apr 25 '12 at 20:44
  • \$\begingroup\$ @madrivereric, interesting on RMS adjustment. I always use a scope unless I have a specific reason. \$\endgroup\$
    – Kortuk
    Apr 25 '12 at 21:08

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