In the figure we show how a 2-pole x 2-position switch or HH should be connected to reverse the direction of rotation of a small DC motor. In the same figure, we give the identification of the poles of this key that can be easily obtained in disused devices or acquired in specialized houses. Note that what this switch does is to reverse the direction of the current flowing through the motor. As the current is reversed, the capacitor after the switch must be made of 100 nF depolarized polyester. For better filtration with an electrolytic capacitor from 100 to 1000 uF, it must be connected before the switch. This circuit is indicated for the case in which a mechanical arm or a robot is controlled, and it must have two-way movements. The key can be kept away from the system by long wires.
