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Re: [Phys-L] USB charger outlets

there are a number of watt meters -- mine a Kill a watt from costco.

The small ones do indeed consume < one Watt, the transformer type generally 3 W. Our TVs idle < one W, but our recorders about 12, IIRC. We have two we use only as players so one switched off using a radio switch (not IR) they unfortunately use a few watts, so perhaps penny wise and pound foolish. I pay the idling cost on the others, so I needn't set the clock.

I've thought to dismantle one of the only a few cubic inchers expecting to find an IC + and a toroid operating supersonically.

bc being deaf can tell which dental drill is air or electrically driven.

Another proof that life is Poisson interval dominated. At the most recent SoCal AAPT section meeting Bill Layton:

"Bill Layton (UCLA)-Transformer basics, wall warts and vampires

In an effort to develop an inexpensive demonstration of reflected transformer impedance, a convincing demonstration evolved to show why the utility companies are worried about the constant power drain from plug in wall transformers, even when the device connected is off or disconnected."

He purchased much higher quality toroidal transformer that consumed negligible power (idling)


On 2012, Dec 21, , at 08:28, Josh Gates wrote:

We all know about the losses caused by leaving wall warts plugged in when not in use (and TVs, etc.), but do these outlets have the same issue?

There are several different types. This one references built-in electronics to sense this and that, which presumably requires some power. Does anybody know the comparison? Along the same lines - does my new phone charger (small block, usb connection to mini usb) have the same issues as the old ones? There doesn't seem to be enough room for a large transformer in there. I don't know if they're smaller or if it's a new technology.


Joshua Gates
Physics Faculty
Tatnall School (Wilmington DE)
JHU Center for Talented Youth
Forum for Physics Educators