Comment RS-232 Christmas Lights (Score 1) 258
Was away on a job for Christmas one year and some of the people wanted to decorate the work space for the holiday. We had a xmas tree but no lights and no way to get any (the company said they couldn't justify a chopper run for xmas lights). I took two wires and soldered them to pins 2 and 5 on a DB-9 connector, then ran the wires parallel to each other about a centimeter apart. Tore apart an old device to get a bunch of different colored LEDs out and then soldered them between the wires every 2-3", reversing the polarity of every other LED (used hot glue to make sure they wouldn't short out). Then I wrote a quick little program to open a serial port and turn the break state on and off at intervals of ~700ms. A serial port's idle state is -5V and its break state is +5V. So when I plugged the connector in, half the LEDs would light on the idle state, and the other half would light on the break state. I would consider that unusual.