I've been messing with the idea of controlling a couple of PWM fans (new 4 pin design) for my PC using a USB interface board i have (Velleman K8055) I am planning long-term to use a PIC to control them eventually bt this is just for testing it out before I commit to spending money.
Now the bit that I'm not 100% sure on is connecting up without causing damage to either the K8055 or the PC. I've found developer specifications for motherboard manufacturers where PWM fan control is used on-board http://www.formfactors.org/developer%5C ... Public.pdf
here is the assembly instructions for the K8055 http://www.velleman.eu/downloads/0/illu ... k_rev3.pdf
towards the end (page 20ish) is a connection diagram.
For testing I am going to connect the 12v and GND to my bench power supply Am i right in thinking that from the specs I should be able to just hook the fans PWM pin straight into the K8055 on the PWM1 terminal and also tie the GND pin on the K8055's PWM header to the PSU ground.
However from the documentation I have absolutely no idea how to hook in the Tacho signal
Thanks for any advice
