(b) The rated speed of a 24 V DC brushed motor is 3000 RPM. Propose and design an op- amp based time-proportional circuit and justify how it can drive the motor over full- speed range. (C) The speed of the DC brushed motor can be controlled precisely in a closed-loop manner. (i) Show how an analog proportional-integral (PI) controller can be integrated into the proposed circuit in (b) (ii) Sketch a block diagram showing the main elements in such PI closed-loop speed control system (iii) Explain how the PI controller improves the speed control of the DC brushed motor. (b) The rated speed of a 24 V DC brushed motor is 3000 RPM. Propose and design an op- amp based time-proportional circuit and justify how it can drive the motor over full- speed range. (C) The speed of the DC brushed motor can be controlled precisely in a closed-loop manner. (i) Show how an analog proportional-integral (PI) controller can be integrated into the proposed circuit in (b) (ii) Sketch a block diagram showing the main elements in such PI closed-loop speed control system (iii) Explain how the PI controller improves the speed control of the DC brushed motor