3 bux
On 2015-10-10, ehsjr wrote:
On 10/9/2015 5:38 AM, Jasen Betts wrote:
On 2015-10-09, Robert Baer wrote:
Jasen Betts wrote:
Impossible for power out to be greater than power in.
I said it's a good deal if you don't look too closely.
Possibly it's measuring average current and voltage, and not RMS.
Or it mught just be reading innacurately. It was like $7 and
change for the pair.
Or the in and out labels are in the wrong places and you have
an 87% efficient boost DC-DC converter. :-)
For what they are, it's really not too bad. 4 meters - $1.50 per
meter - with maybe +/- 3.3% error each. At that low cost, they
undoubtedly were not "factory calibrated". So if you wanted to take
the time and effort, you might be able to spin a pot and file
(or add solder to) a shunt to get better accuracy. But really,
these meters should be used just to give one a rough idea of
voltage & current.
I'll swap them on monday and see if the error moves, and also do
some comparisons against some slightly more expensive meters.
--
\_(ツ)_
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