[Beowulf] Re: power usage, Intel 5160 vs. AMD 2216

David Mathog mathog at caltech.edu
Sun Jul 15 15:46:13 PDT 2007

Greg Lindahl <lindahl at pbm.com> wrote

> So, the thing that logs power usage over time seems to be the "Watts
> Up Pro", which says that it plugs into USB and has a Windoze program that
> graphs power usage. Does anyone have one, and can you access the data
> sans Windoze program? Are there any other cheap logging power meters?

The Watts Up Pro is only $130 at Amazon right now - if your
time is worth anything just buy one.

If this is a one time deal and you  have a USB Camera you
set it to snap pictures of the display at fixed intervals, and
then scan through those later.

Or, if you already own a USB data logger and a Kill-a-watt, try
this at your own risk. Most likely you'll end up filing the effort
under "I wish I'd just spent the money on the data logging version"!

On opening up a Kill-a-watt you'll find that one side has all the power
goodies and a tiny amount of logic, and the other side contains the
display, the buttons, and what looks like the logic to control the 
display.  The two sides are connected by a 6 wire cable, where
all of the wires are the same diameter, with no shielding and no
twisted pairs.  It seems likely that if one attached a voltmeter
to those 6 wires one would find a ground, 5V (or 12V) dc, and
4 measurement lines, probably representing Line Voltage, Current, Line
Frequency, and Power.  If you're lucky the measurement values are
encoded as a DC voltage. That would be easy to test, and if true,
you could solder leads onto those 6 lines and bring them outside
the case to attach to the input leads of your existing USB data
logging device.


David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech

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