My Light 2

I was really bored, so I invented a device which allows me to turn the lights in my bedroom on and off simply by connecting to a webpage. This works from any computer (assuming it knows the link), or from any phone capable of connecting to the internet.

I soldered the circuits and connectors myself, and wrote the software myself; everything was built from scratch.

It uses a relay attached to a transistor switch which is attached to the computer's parallel port. I wrote software (in C++, running on a very basic Linux setup) which, upon receiving a connection request, sends voltage back out through the parallel port, activating the transistor, allowing voltage to flow through to the relay. The power is drawn from the computer's 9v power supply (I soldered a connector to make it easy to plug in to the computer).

This is the most useless device ever created.