The evening was well spent. A friend came over and helped build a project we’ve been talking a lot about at Samfundet: an interface for opening the door from a computer. Naturally, we had to connect this to an IRC bot, so now we can open the door by saying “dør!” (Norwegian for “door”) on IRC. Not a very hard project, except we wasted a bit of time with some wrongly sized resistors because of a silly calculation error.
The interface is a parallell cable connected to an optocoupler, whose inputs are in parallell with a 220 Ohm resistor. The output is coupled directly to a wall knob which one can punch to open the door as well. (That’s the reason why we started the project in the first place: we were too lazy to walk over and punch the button.)