U1a to U1d comprise two window comparators. U1a and U1d is a fixed window comparator
which sets the motor forward and reverse maximum or limit and so protects the circuit from control malfunction or motor overshoot.
U1b and U1c control motor distance of travel in both forward and reverse direction and so sets the operational window of the circuit. This distance of travel or rotation is adjusted via U2a and U2b input which are summing amplifiers. The output from U2a is negative while the output from U2b is positive.The output from U2a sets the trip point of comparator U1b and the output from U2b sets the trip point of comparator U1c. |
