Distinguishing voltage stabilizing diode

How to identify Zener Diode.
Positive and negative pole recognition.
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. This refers to the pointer multimeter.
Identification of color ring voltage stabilizing diode.
Domestic products of color ring Zener diodes are rare, most of them come from abroad, especially Japanese products. In general, color ring Zener diodes are marked with models and parameters, and details can be found in the component manual. On the other hand, the color ring voltage regulator diode has the advantages of small size, low power and voltage regulation value of less than 10V, so it is easy to break down. The appearance of the color ring voltage regulator diode is very similar to the color ring resistance, so it is easy to make mistakes. The color ring on the color ring Zener diode represents two meanings: one represents the number of digits, and the other represents the number of decimal places (usually the color ring Zener diode takes a decimal place and is represented by brown. It can also be understood as the multiplier: × 10 (to the power of-1), the digital homochromatic ring resistance corresponding to the specific color).
Because of the small size of the low power Zener diode, it is difficult to mark the type on the diodee, so some foreign products use the color ring to express its nominal stable voltage value. Like the color ring resistance, the colors of the ring are brown, red, orange, yellow, green, blue, purple, gray, white, and black, which are used to represent the values 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, respectively.
Some Zener diodes have only two color rings, while others have three. The first ring is closest to the negative pole, followed by the second ring and the third ring.
Having only two color rings. The nominal stable voltage is double digits, that is, "× × V" (several dozen volts). The first ring represents the value on the ten bits of the voltage, and the second ring represents the value on the individual bit. For example, if the first and second rings are red and yellow in turn, it is 24V.
There are three color rings, and the second and third color rings have the same color. The nominal stable voltage is an integer with a decimal place, that is, "×. × V" (a few volts). The first ring represents the value on each bit of the voltage. The second and third color rings (the same color) together represent the value of ten places (the first place after the decimal point). For example, if the colors of the 1st, 2nd and 3rd rings are gray, red and red in turn, it is 8.2V.
There are three color rings, and the second and third color rings are different in color. The nominal stable voltage is a two-digit integer with a decimal place, that is, "× ×. × V" (tens of points and volts). The first ring represents the value on the ten digits of the voltage. The second ring represents the numerical value in each bit. The third ring represents the number of ten places (the first place after the decimal point). However, this situation is rare, such as the comparison table of common Zener diodes of brown, black, yellow (10.4V) and brown, black and gray (10.8V). (note: the latter diode model begins with 1, such as 1N4728M 1N4729, etc.).
Distinction from ordinary rectifier diodes.
First of all, the R × 1K block of the multimeter is used to judge the positive and negative electrodes of the tested diodee. Then set the multimeter to the R × 10K block, the black meter pen connects the negative pole of the tested diodee, and the red meter pen connects the positive pole of the tested diodee, if the reverse resistance measured at this time is much smaller than that measured with the R × 1K block, it shows that the tested diodee is a voltage stabilizer diodee; on the contrary, if the measured reverse resistance value is still very large, it means that the diodee is a rectifier diode or a detection diode. The reason of this identification method is that the battery voltage used in the R × 1K block of the multimeter is 1.5V, which generally does not break down the measuring diodee in the reverse direction, so that the measured resistance is relatively large. When the R × 10K block is measured, the voltage of the battery in the multimeter is generally more than 9V. When the tested diodee is a voltage stabilizer and the shearing voltage value is lower than the battery voltage value, it will be broken down in the reverse direction, so that the measured resistance value is greatly reduced. However, if the diodee under test is a general rectifier or detection diode, the resistance value will not be very different whether measured with R × 1K block or R × 10K block. Note that when the voltage stabilized value of the measured Zener diode is higher than that of the R × 10K block of the multimeter, it is impossible to distinguish by this method.