Semiconductor diodes are primarily composed of a PN junction, along with electrodes, lead wires, and tube shells. The electrode connected to the P-type semiconductor is the anode of the diode, while the electrode connected to the N-type semiconductor is the cathode. The basic characteristics of a diode are similar to those of a PN junction. The most significant feature of ordinary diodes is their unidirectional conductivity. Due to this characteristic, diodes are often used in electronic circuits for rectification, detection, voltage regulation, and other functions. When the effective value of the transformer secondary voltage and the load resistance in the rectifier circuit are determined, the requirements for diode parameters are also established. Generally, the diode model is selected based on the average current flowing through the diode and the maximum reverse voltage it can withstand.