This is something I built for a friend from work (Matthieu) one thursday evening. It's used to wake up a shut PC.
My friend has a computer that he uses to record shows from the TV.
It's pretty much a similar system to mine, except that my
TV-recording-computer also has some other duties so it's always on.
Matthieu on the other hand, doesn't want to keep his computer on all the
time, so the computer should be able to wake up automatically at a pre-set
time to record a scheduled show. And this is what this device enables.
So how does it work?The device gets it's power from the Wake-on-LAN port even when the computer is turned off. Before shutting down, the computer tells this device through the parallel port when the computer wants to be waken up again. The computer can now shut down, and the device counts down the required time. After the time has passed, the device starts the computer using the Wake on LAN -port. Pretty simple, eh?
To those interested, the program for the microcontroller (Microchip PIC 16F84A) has been programmed using the Jal programming language. You can find the source codes and the compiled programs here:
pctimer.jal, pctimer.asm, pctimer.hex
The sources for the PC software: wake.c
...And here's the schematic of the device:
You can read more about this at Matthieu's blog entry about the device.