Using
http://pcbheaven.com/circuitpages/images/linearfancontrol_1269972793.png to start basically; I built the circuit on vero-board and tested it; having just one fan powered, it spins at a slow speed, and turning pot makes no change.
My DMM has been dropped one too many times and now displays garbage unless I apply pressure on the LCD, so taking measurements is a pain in the ass, if I had to guess though, the voltage would be around ~2v across Fan+ and ground; the pot is replaced with a 10k variable resistor right now.
The fan I tested it with has 4 blue LEDs and they just barely light up.
R1 is supposed to be 5k pot
R2 is 100ohm
R3 is 10k ohm
C1 is 10uF
C2 is 470uF
Q1 is supposed to be BD243, I've got a 2SC1384 in it's place
If I replace Q1 with a transistor I grabbed from a dead CFL (DD128F, can't find a datasheet for it), the fan speed is faster, but same problem of no control. :/
It's supposed to be an "emitter follower" setup for current gain, for the fan(s), so why would changing the transistor change the voltage?
Any help would be appreciated. :3