On Wed, Aug 20, 2003 at 12:33:12PM -0600, Paul E Condon wrote: > > > Also, Radio Shack sells a "current transformer" which is an add-on device > for their digital multimeter. With the multimeter and the current transformer > you can measure current and voltage on the AC supply input to the computer. > Or to any other electric device about which you are curious. ...but this arrangement will only give you a useful reading if the current waveform is sinusoidal. The current drawn by a PC is most definitely not sinusoidal; the rectifiers in the PSU only conduct on the peaks of the voltage waveform, so the current waveform looks like a series of narrow spikes of alternating polarity. The common-or-garden multimeter does not perform a true RMS conversion, and won't give a sensible result on this sort of waveform. (Also, you have to separate the live and neutral conductors in the power lead so the current transformer can be fitted round one conductor only, which is a pain.) -- Pigeon Be kind to pigeons Get my GPG key here: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x21C61F7F
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