I'va made one of these, but it got me thinking - how should this be modified to allow to control all 4 fans with one 555 timer on one PCB?
(sorry for my poor english)
- I've made two boards, one is for FAN1/2 and another is for FAN3/5. (SENS pins are individual)
- some newer version of BMC firmware checks as if the fans are controllable by PWM, so I used a version of 4.23.
- this analog method is very cheap, but I think it's more better to use microcontroller.