Dropping the 19v power supply to 12v 80mm fan using only the parts i had took a bit of thinking. At first i found a L7812 voltage regulator in my electronics bits box and created a suitable circuit for this and the fan on the my breadboard. But found that the regulator was a goner. I have big box of 1/4 watt resistors of all sorts of resistances. So i thought some kind of potential divider should work well. Only problem was that the heat dissipated from the potential divider would be far greater then 1/4 watt from a single resistor. Solution: use lots and lots of resistors! When using resistors in series or parallel the wattage dissipation adds together. I cant remember how much power the potential divider had to dissipate, i think it something like 3-4 watts. So approximately 16 resistors would do the job. You can see from the featured picture how i wired it up. It worked a charm. At time of doing this i was super busy with college so permanent fancy circuit board was out of the question. Oh yes the 80mm fan was basically attached to the front panel of the electronics box seen in previous posts.