A diode is an electronic device made of semiconductor materials (silicon, selenium, germanium, etc.). The diode has two electrodes, the positive electrode, also called the anode; The negative electrode, also called the cathode, when the positive voltage is added between the two poles of the diode, the diode is switched on, and when the reverse voltage is added, the diode is cut off. The conduction and cutoff of the diode are equivalent to the switching on and off