What is a Zener Diode

What is a Zener Diode.
From the point of view of the shape, the positive end of the metal encapsulated Zener diode is planar and the negative end is semicircular. One end of the plastic-encapsulated Zener diode body with color marks is a negative pole, and the other end is a positive electrode. For the Zener diodes whose marks are not clear, the polarity of the Zener diodes can also be distinguished by the multimeter, and the measuring method is the same as that of the ordinary diodes, that is, using the multimeter R × 1k, the two meters are connected to the two electrodes of the Zener diodes respectively, and a result is obtained. Then adjust the two meter pens to measure. In the two measurements, when the resistance value is smaller, the black meter pen is connected to the positive pole of the voltage regulator diode, and the red meter pen is connected to the negative pole of the voltage regulator diode. If the forward and reverse resistors of the Zener diode are very small or infinite, it means that the diode has been broken down or damaged by open circuit.
The value of voltage regulator is measured by 030V continuous adjustable DC power supply. for the voltage regulator diode below 13V, the output voltage of the voltage regulator diode can be adjusted to 15V, the positive pole of the power supply is connected with a 1.5k Ω current limiting resistor, and then the negative pole of the power supply is connected with the positive pole of the voltage regulator diode, and then the voltage value of the Zener diode is measured with a multimeter, and the measured reading is the voltage regulator value of the Zener diode. If the stabilized value of the Zener diode is higher than 15V, the Zener power supply should be adjusted to more than 20V. A megohmmeter less than 1000V can also be used to provide test power for Zener diodes. The method is as follows: the positive end of the megohmmeter is connected with the negative pole of the voltage regulator diode, and after the negative end of the megohmmeter is connected with the positive pole of the voltage regulator diode, the handle of the megohmmeter is shaken at a uniform speed according to the stipulation. At the same time, the voltage value at both ends of the voltage regulator diode is monitored by the multimeter (the voltage range of the multimeter should depend on the stable voltage value). When the indication voltage of the multimeter indicates stability, this voltage value is the stable voltage value of the Zener diode. If the stable voltage value of the Zener diode is measured from high to low, it shows that the diode is unstable.