I was bored today so I made an adjustable voltage regulator using some parts from my toolbox. It runs a 12V .18A DC fan from a 5V supply off my power supply unit.
It’s adjustable to well past 12V (probably around 13-14V) down to 5V. This would make a nice little fan controller circuit but it probably a little overkill since most people haver 12V to work from anyways ;) (and I doubt it’d draw as much power too). It draws about 400mA off the 5V line to drive the fan at 12V@0.18A.
And Prof Jacob would be proud. I don’t have a scope, but my DMM only read 50-70mVrms noise on the output ;)