Share nine tips for detecting Schottky diodes

　　1. Detect low-power Schottky diodes


　　A. Identify the positive and negative electrodes


　　(a) Observe the symbol on the outer shell. The Schottky diode symbol is usually marked on the outer shell of the Schottky diode. The end with a triangular arrow is the positive electrode and the other end is the negative electrode.


　　(b) Observe the color dots on the outer shell. The outer shell of the point-contact Schottky diode is usually marked with polarity color dots (white or red). Generally, the end marked with the color dot is the positive electrode. Some diodes are marked with color rings, and the end with the color ring is the negative electrode.


　　(c) Based on the measurement with a smaller resistance value, the end connected to the black test lead is the positive electrode, and the end connected to the red test lead is the negative electrode.


　　B. Detect the highest reverse breakdown voltage. For alternating current, because it is constantly changing, the highest reverse working voltage is also the peak AC voltage that the Schottky diode can withstand.

　　2. Detection of bidirectional Schottky diodes


　　Set the multimeter to the corresponding DC voltage block. The test voltage is provided by the megohmmeter. During the test, shake the megohmmeter and measure the VBR value in the same way. Finally, compare VBO with VBR. The smaller the difference between the absolute values ​​of the two, the better the symmetry of the bidirectional trigger Schottky diode being tested.


　　3. Detection of transient voltage suppression diodes (TVS)


　　A. Use a multimeter to measure the quality of the tube For single-pole TVS, the forward and reverse resistances can be measured according to the method of measuring ordinary diodes. Generally, the forward resistance is about 4kΩ and the reverse resistance is infinite.


　　For bidirectional TVS, the resistance value between the two pins measured by arbitrarily exchanging the red and black test pens should be infinite, otherwise, it means that the tube has poor performance or is damaged.


　　4. Detection of high-frequency variable-resistance Schottky diodes


　　Identify the positive and negative poles. The difference between the appearance of high-frequency variable-resistance Schottky diodes and ordinary diodes is that their color codes are different. The color code of ordinary diodes is generally black, while the color code of high-frequency variable-resistance Schottky diodes is light. Its polarity rule is similar to that of ordinary diodes, that is, the end with a green ring is the negative pole, and the end without a green ring is the positive pole.


　　5. Detection of variable-capacitance Schottky diodes


　　How to swap the red and black test leads of the multimeter for measurement, the resistance value between the two pins of the variable-capacitance Schottky diode should be infinite. If during the measurement, it is found that the multimeter pointer has a slight swing to the right or the resistance value is zero, it means that the variable-capacitance Schottky diode being measured has a leakage fault or has been broken down.


　　6. Detection of monochrome luminous Schottky diodes


　　Attach an energy-saving 1.5V dry battery to the outside of the multimeter and set the multimeter to R×10 or R×100. This connection method is equivalent to giving the multimeter a 1.5V voltage in series, so that the detection voltage increases to 3V (the turn-on voltage of the light-emitting diode is 2V). When testing, use the two test pens of the multimeter to alternately touch the two pins of the light-emitting diode. If the performance of the tube is good, it must be able to emit light normally once. At this time, the black test pen is connected to the positive pole and the red test pen is connected to the negative pole.


　　7. Detection of infrared light-emitting Schottky diodes


　　A. Determine the positive and negative electrodes of infrared light-emitting Schottky diodes. Infrared light-emitting Schottky diodes have two pins, usually the long pin is the positive pole and the short pin is the negative pole. Because the infrared light-emitting Schottky diode is transparent, the electrodes in the tube shell are clearly visible. The wider and larger internal electrode is the negative pole, and the narrower and smaller one is the positive pole.


　　B. First measure the forward and reverse resistance of the red light-emitting Schottky diode. Usually the forward resistance should be around 30k, and the reverse resistance should be above 500k. Such tubes can be used normally.


　　8. Inspection of infrared receiving Schottky diodes


　　A. Identify the polarity of the pins


　　(a) Identify from the appearance. Common infrared receiving Schottky diodes have a black appearance. When identifying the pins, face the light receiving window, from left to right, they are positive and negative. In addition, there is a small chamfered plane on the top of the infrared receiving Schottky diode body. Usually, the pin with one end of this chamfered plane is the negative pole, and the other end is the positive pole.


　　(b) First use a multimeter to identify the positive and negative electrodes of ordinary Schottky diodes for inspection, that is, swap the red and black test leads to measure the resistance value between the two pins of the tube twice. Under normal circumstances, the resistance value should be one large and one small. The one with the smaller resistance value shall prevail. The pin connected to the red test lead is the negative pole, and the pin connected to the black test lead is the positive pole.


　　B. Detect the performance. Use the resistance block of the multimeter to measure the forward and reverse resistance of the infrared receiving Schottky diode. According to the size of the forward and reverse resistance values, the quality of the infrared receiving Schottky diode can be preliminarily determined.


　　9. Testing of Laser Schottky Diodes


　　A. According to the method of testing the forward and reverse resistance of ordinary diodes, the pin arrangement order of the laser Schottky diode can be determined. However, it should be noted during testing that since the forward voltage drop of the laser Schottky diode is larger than that of ordinary diodes, the multimeter pointer will only slightly deflect to the right when testing the forward resistance.