the north wind 2 installed in my computer

the backside of the north wind 2

yes my design has diodes on it I just didn't bother taking them off, they were from a previous design that didn't work

this is a drawing of the perf board I used for the north wind 2

the spdt switch represents the jumper block, the spst switch switches the full 12 volt power to the fan bypassing the pot and transistors

the pots used for the prototype are 10K linear taper pots

there are 3 transistors because of there low currant load only 800ma, you could use larger transistors and use fewer

I got the ones I used from the source there was 15 in the pack.

the motor obviously is the fan

this shows 1 channel for my controller, build as many as u need, just use the same power rails and optionally the same low rail switch for all channels

this is a drawing of the fan adapter cable with rpm pass throw