To start a motor from a set of batteries, battery or power supply the indicated circuit is the one shown in the figure where the polarity of the motor connection will determine its direction of rotation. The capacitor is used to dampen the switching of the motor brushes, making their operation smoother and avoiding the production of transient pulses in the powered circuit. This component is especially important when the used battery powers other circuits at the same time, because without the capacitor interference can occur. If the circuit uses a remote control, the capacitor is important as it prevents the irradiation of interference. Values between 100 uF and 1000 uF with working voltage slightly higher than that used in the power supply can be used, observing their polarity.
