So I'm reading about a guy who modded a LAN hub into his system and I think--cool, I like it. Then I started thinking about some stuff and got to wondering--is there a simple circuit that will let you place a sensor in front of an LED, and when that LED lights it will light another LED somewhere else? I know I could just rip open this hub and wire to its LED's, but I was wondering about a solution that wreaks less havoc on the device? Any ideas?
This can be done via fiber optics, or you can put a photo transistor, one end connected to +5v and the other to your LED's With a current limiting resistor of course. But often the LED wont be bright enough to do this. It may be worth moving the LED, or taping off the signal to a transistor. (You don't have to de-solder the LED just solder to one point on it)
As for the mechanics of it, heat-shrink tubing is your friend. This guy used a LDR, but you could swap for other photo-sensors. Interesting site, this was part of an early design for a gizmo to switch computer or hi-fi peripherals (printer, monitor, active speakers, etc) on when the main unit draws current. Final design here.
