The circuit shown in the figure can drive a motor (or other type of load) for a time interval that depends on capacitor C. For good quality capacitors (polyester or electrolytic) the times can reach a few minutes. The maximum current, in the order of a few amps, depends on the Power FET used. By pressing S for a moment, the capacitor charges and keeps the FET driving. When the capacitor is discharged, the transistor goes to the cutoff, turning off the motor. We observed that there is a range of times when the transistor operates in the linear region of its characteristic curve and the current gradually drops in the load. In other words, cutting the load current is not abrupt.
