Hello,
I'm building the circuit seen here:
https://www.youtube.com/watch?v=TF018JPytSg
To control the speed of some 3 pin fans from the 4 pin headers on my computer motherboard. The circuit diagram has no output capacitor, but you can see it in the video, and it's mentioned in the comments, but not the value of the capacitor. Looks like a small ceramic cap to me. What would be a good value for this capacitor, and is it even needed?
Another question I have is about a freewheeling diode, shouldn't this circuit have one? Or maybe it's depending on one typically already installed in the fans?
Here are the design specs for 4 wire fans:
http://www.formfactors.org/developer/specs/4_Wire_PWM_Spec.pdf
The PWM is signal ~25khz, I'll be using a picaxe to generate this for testing the circuit.
Thanks!
I'm building the circuit seen here:
https://www.youtube.com/watch?v=TF018JPytSg
To control the speed of some 3 pin fans from the 4 pin headers on my computer motherboard. The circuit diagram has no output capacitor, but you can see it in the video, and it's mentioned in the comments, but not the value of the capacitor. Looks like a small ceramic cap to me. What would be a good value for this capacitor, and is it even needed?
Another question I have is about a freewheeling diode, shouldn't this circuit have one? Or maybe it's depending on one typically already installed in the fans?
Here are the design specs for 4 wire fans:
http://www.formfactors.org/developer/specs/4_Wire_PWM_Spec.pdf
The PWM is signal ~25khz, I'll be using a picaxe to generate this for testing the circuit.
Thanks!