Re: Measuring Power dissipation emperically

On Sun, 13 Apr 2008 02:02:27 -0600, "Jon Slaughter"
<Jon_Slaughter@xxxxxxxxxxx> wrote:

How does one go about measuring the power dissipation of a device(low
voltage) emperically? Stick it in water? Use a large heat sink? (talking
about the long term average and not instantanous obviously)

You're measuring the wrong thing. What you want is the temperature of
the device, not the power dissipation. Power dissipated and converted
to heat is nothing more than AC/DC power input, minus whatever goes
out. You can measure those all you want, but it won't tell you the
final temperature of the device. Over a long term, you can use stick
on temperature indicators for measuring the upper extreme, or whatever
data logger you can borrow, for continuous measurement.

However, you wanted an empirical measurement:
<http://en.wikipedia.org/wiki/Empirical>
which implies that one cannot use test equipment or measuring devices,
and must use your senses (touch, observation, smell, hearing, etc).
Been there, done that. Put your finger on the heat source. If you
can hold it there, the cooling system is working. If you have to
remove your finger after about 15 seconds, it's at the upper border of
acceptable. If you burn the hell out of your finger, you need a
bigger heat sink.

You can also detect if something is over temperature by smell. If the
device smells like it's melting or burning, it's too hot. Similarly,
you can also test for overtemperature by sight. If there's smoke or
flames coming from the device, you've exceeded the manufacturers
suggested operating conditions.

I'm not sure what you mean by "long term average". I would be rather
uncomfortable leaving my finger on the test device for several days or
weeks. Perhaps you had something more specific in mind? Maybe
empirical isn't the correct word?

--
Jeff Liebermann jeffl@xxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.

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