Tag: Motor Control

A permanent split capacitor (PSC) motor has a run type capacitor. This capacitor is permanently connected in series with the start winding. This will cause the start winding an auxiliary winding once the motor reached the running speed. It cannot provide the starting boost of a starting capacitor since the run capacitor must be designed for continuous use. PSC motor […]

Modified split-phase motor with a capacitor in series with the start winding to provide a start “boost” is shown below. The capacitor start motor also has a centrifugal switch like the split-phase motor which disconnects the start winding and the capacitor when the motor reaches about 75% of the rated speed. It creates more starting torque, typically 200% to 400% […]

We can purchase DC motors with or without brushes with ac tachometer outputs already provided by the manufacturer. A very low cost speed control can be constructed with these motors in combination with the LM2907. The most simple version is illustrated in figure below where the tachometer drives the non inverting input of the comparator up towards the preset reference […]

The following figure show us an alternative approach which gives proportional control. The charge pump integrator is shown in a feedback connection around the operational amplifier. For zero speed, the output voltage is equal to the reference voltage set up on the potentiometer on the non inverting input. The charge pump puts charge into capacitor C2 and causes the output […]