Double-knife, double-throw switch and the gate knife connected to the two terminals and the left two terminals or the right two terminals, respectively, power supply, the fan is connected, and double-knife, double-throw switch two terminals on the left and two terminals on the right connected to each other, so that through the fan in the direction of the current changes.
Program 1: so that the power supply E and b, e connected; electric fan F and c, f connected; a and f connected, c and d connected. As shown in the figure
Option 2: Connect the fan F with b and e; connect the power supply E with a and d; connect a with f and c with d. As shown in the figure