I've been playing with a cool little switch that is great for laptop users. It is the Gigafast EZ500-S. This is the smallest 5-port switch that I've seen; 110mm x 70mm x 19mm (4.33" x 2.75" x 0.75"). Mine cost $10 after a $10 rebate. I got the blue metal cased version.
The thing that I didn't like about the switch is that the wall-wart is almost as big as the switch. I thought that it would be a great idea to modify the switch such that I could use the laptop power brick with it. This way I will only have to carry one power brick in the laptop bag.
Time to void the warranty... <g>
When I opened the unit I was pleasantly surprised to find a MC34063A based DC-DC converter for power regulation. This chip can regulate input voltages from 3-40v. I checked as many of the values of the surrounding components as I could and determined that the regulator should be able to handle the 18.5v from my laptop power brick. (click here for a design tool) The next step was to smoke test it. I plugged in the 18.5v and the switch powered on normally. I checked the output voltage of the regulator and it was good. I love it when things are this easy.
I've been running my switch for the last couple of hours at the higher voltage. So far so good.
BTW, I would not recommend that anyone just plug in a higher voltage supply into a switch without checking out the power regulation circuit first. A coworker of mine fried his switch by doing this accidentally.
I've also tried the same procedure on a Gigafast EZ800-S. This also works with a 18.5v supply. It uses the same regulator chip as the EZ500-S but in a different configuration. I'm a bit less confident about the long term effects of "over-volting" this device.
As always, YMMV.
Electronics run on smoke, if you let the smoke out they won't work