HOW to control a 3-WIRE FAN speed and PULSE MEASUREMENT per Rotation - Test in Practice 

Thanks, that was helpful.

Well explained. Keep it up!

I want to adapt a new fan in a circuit where it has a faster fan but the same amount of airflow. This circuit has a protection that trips because of the lower speed of the new fan. Can I make a circuit to multiply the pulses sent by the fan's tach?

I know this is 2 years old, but I'm curious. Do you need the resistor to control fan speed or ca you just adjust the power cutting the yellow wire? I'm thinking of using a septic dc to dc buck boost converter to control speed of 5 fans. Any thoughts?

Can i use this schematic convert 3 pin to 2 pin CPU fan ? (Without Controller)

If we do not have an oscilloscope, is there any other way to detect the f of the fan to find rpm and pulse?