Method for detecting diode

B. detects the highest reverse breakdown voltage. For AC, because of the constant change, the maximum reverse operating voltage is the AC peak voltage that the diode is subjected to.
Detecting bidirectional trigger diode
Place the multimeter in the corresponding DC voltage barrier. The test voltage is supplied by a trillion ohm meter. When testing, shake the VBR and measure the value of the same way. Finally, comparing the VBO with the VBR, the smaller the absolute value, the better the symmetry of the bidirectional trigger diode is tested.
Transient voltage suppressor diode (TVS) detection
A. measure the quality of the tube with a multimeter. For the single pole type TVS, according to the method of measuring common diode, the positive and reverse resistance can be measured. The general forward resistance is about 4K, and the reverse resistance is infinite.
For the double pole type TVS, any exchange red, black test to measure the resistance of the two pin between the values should be infinite, otherwise, that bad performance or damaged pipe.
Detection of high frequency variable resistance diode
The difference between variable resistance diode diode in the appearance of the identification of positive and negative frequency is the color of different colors, color color ordinary diode is black, color color and high frequency variable resistance diode is light. Its polarity law is similar to that of ordinary diode, that is, one end with green ring is negative pole, without green ring, one end is positive pole.
Detection of variable capacitance diode
The multimeter red and black pen on how to measure resistance of varactor diode two pin between the values should be infinite. If the meter is found to have a slight swing to the right or the resistance to zero in the measurement, it is indicated that the measuring diode has an electrical leakage fault or has already broken down.
Detection of monochromatic LED
An energy-saving 1.5V dry battery is attached to the meter outside, and the multimeter is placed in R * 10 or R * 100 blocks. This connection is equivalent to a multimeter, connected to the 1.5V voltage, so that the detection voltage increased to 3V (light-emitting diode open voltage of 2V). Contact detection, led two pins with table two pens with 000 rotation. If the performance is good, there must be a normal light, at this time, the black probe connected to the cathode anode for the red pen.
Detection of infrared LED
A. distinguishing positive and negative electrodes of infrared led. The infrared LED has two pins, usually the long pin is the positive pole and the short pin is the negative one. Because the infrared light emitting diode is transparent, the electrode inside the tube shell is clearly visible, the internal electrode is wider, the larger one is negative electrode, and the narrower and smaller one is an anode.
B. first measure the positive and reverse resistances of the red LEDs. The normal forward resistance should be about 30K, and the reverse resistance should be above 500K, so that the tubes can be used normally.
Detection of infrared receiving diode
A. identification of pin polarity
(a) identify by appearance. The common infrared receive diode is black in appearance. When identifying the pins, facing the light window, from left to right, they are respectively positive and negative. In addition there is a small oblique plane at the top end of the tube body infrared receiving diode, usually with the chamfered end of the pin plane is negative, the other end is positive.
(b) check with the method of distinguish the positive and negative electrode of the diode, the resistance is the exchange of red, black pen two measuring tube pin two and the value of the normal, the resistance should be a small. With a smaller resistance as the standard, the pace of the red pen tube as anode, pin connected to the positive black pen.
B. test performance is good or bad. Measure the positive and negative resistance of infrared receiving diode by the resistance gauge of multimeter. According to the size of positive and reverse resistance, we can judge the quality of infrared receiving diode preliminarily.
Laser diode detection
A. according to the method of detecting the positive and negative resistance of the common diode, the arrangement order of the pins of the laser diode can be determined. However, it is important to note that the forward voltage drop of the laser diode is greater than that of the common diode, so when the forward resistance is detected, the meter pointer deflects slightly to the right.