Motor rotation control circuit. Lets you measure the rotation speed and control it by a PWM signal which is turned into a constant DC voltage from 0V to 5V.
The output signal is made of two parts: 1. a constant offset voltage, which can be adjusted by a trimmer, 2. a PWM-regulated voltage, which is subtracted from the constant part. The range of the PWM-regulated part can also be adjusted by a trimmer.
There is also a programmable analog switch to switch between a constant voltage to stop the motor and the generated signal.