"mm" wrote in message
...
On Wed, 13 Jun 2007 14:51:20 -0400, "Zephyr" an address @ some place
.com wrote:

Hey folks,

I'm curious about power consumption of things like the power supply for my
dell laptop
its and AC/DC adaptor, and when the unit is charging my laptop it gets
quite
warm.
from that I infer that its using a fair amount of power.

now, if I leave it plugged into the wall, but remove the laptop, it does
not heat up, but.
there is a little light on it that indicates it is receiving power.
aside from that little light, is it using any significant amount of
power?
The label on the unit says the input is 1.5a

same question goes for my cell phone chargers 0.2a

I understand that some of these things do use power constantly, but... how
much?

Good question. Not only the ones with wall warts, those black
"adaptor" boxes that plug into the wall with a cord coming out of
them, but many radios etc. with the transformers inside, have no
switch in the primary of the power transformer, and they are ON all
the time.

For electronic reasons I don't well understand, when there is no
current in the secondary of a transformer, there is higher impedance
in the primary of the transformer, so less current flows even through
the primary. The heat one can feel, that you feel, the waste heat
would be iiac the same percentage of energy used, as when the device
is running and there is current through the secondary.

From your touch, it sounds like the current is a lot lower, but otoh,
it's on all the time if the thing is plugged in, even for things that
are only used an hour a year.

Does anyone know what the percentage is, or how much these things use
when off?



You can pick up a gadget called a Kill A Watt and other similar devices for
under 30 bucks. It's a pretty impressive power analyzer, the wonders of
modern technology. Pick up one of those and you can find out how much power
anything in the house draws, as well as the power factor, cumulative
consumption, etc. I have one and love it.