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The Tuesday 2008-01-08 at 06:47 +0100, Jon Clausen wrote:
On Mon, 07 Jan, 2008 at 16:40:48 +0100, Carlos E. R. wrote:
It would be possible to design one. The device only needs to monitor the
presence of power in the usb power line coming from the laptop, and 1mA
would be enough to trigger the base of a transistor that would in turn
power up the device. It could even be designed around an optocoupler/triac
to power up the AC side of the device.
You just pay an engineer, and he'll do appropriate wonders :-)
Too late, it's been done;
http://www.elsparefonden.org/public-and-commerce/products/energy-saving-equipment/Elspareskinne
Better:
<http://www.elsparefonden.org/public-and-commerce/products/energy-saving-equipment/Elspareskinne/facts-and-figures/how-the-elspareskinne-works>
But that doesn't say how this particular piece works. Typically it would
use a relays to switch off the rest of the equipment, but a relays draws
significant power from the usb bus of a portable running on battery. What I
described were methods to do the same as already known to exist, but
designed for laptops.
- --
Cheers,
Carlos E. R.
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