Monochromatic light emitting diode detector multimeter externally attached a saving 1.5V batteries, set the multimeter R × 10 or R × 100 block. This connection is equivalent to giving a multimeter in series on the voltage of 1.5V, the detection voltage is increased to 3V (light-emitting diode turn-on voltage of 2V). Detection, LL34 diodes, two pen rotation with a multimeter contact with the light emitting diode two pins. If the tube performance is good, there must be a normal light, this time, the black pen connects to the positive red lead connection is negative. A. detect infrared light emitting diode infrared light-emitting diode discriminating positive and negative electrodes. Infrared light-emitting diode has two pins, usually longer pin is positive, the short pin is negative. Because infrared light-emitting diodes are transparent, so that the envelope of the electrode is clearly visible, the larger a wider internal electrode to the negative electrode, and a narrow and small as the positive electrode. B. Measure the red light-emitting diode, the reverse resistance, usually forward resistance should be about 30k, 500k reverse resistance to the above, diodes, such as pipe before normal use. Voltage characteristics of the semiconductor diode diode anode: the P region as the anode electrode leads. Cathode: N district drawn by the cathode electrode. Point-contact diode, the current through a small, small junction capacitance for high frequency circuits and switching circuits. Surface contact type diode, SMD diode junction area, current, junction capacitance, suitable for low-frequency rectifier circuit. Planar diode junction area is larger by a large current, for high-power rectifier junction area is small, it can be used as a digital circuit switch. Divided by material germanium, silicon or gallium arsenide; by the structure a little touching, pn junction, pin, Schottky barrier, heterojunction; divided according to the principle of the tunnel, varactor, avalanches and step recovery. Mainly used for detection, mixing, parametric amplification, switches, regulators, rectifier and so on. After the development of optical communication, appear light, photoelectric, avalanche photodiodes, pin optoelectronics, semiconductor laser diodes. Diodes mainly by PN junction and work. PN junction and indivisible point-contact and Schottky type, are also included within the scope of a general diode. Including these two models, including, according to the characteristics of PN structure made plane, the crystal diode classified as follows: point-contact point contact diode is on a single wafer of silicon germanium or a metal pin contact pressure, and then by the current Method formed. Thus, the PN junction capacitance is small, the diode-line for high-frequency circuits. However, compared with the junction type, point-contact diode forward characteristics and backward characteristics are poor, therefore, can not be used for large current and rectification. Because the structure is simple, it is cheap. DO35 Diode _ gold credit (certified) _ diode provided by Qingdao integrity Technology Co., Ltd. Qingdao integrity Technology Co., Ltd. (www.qdjcx.com) is in Qingdao, Shandong diode leaders, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs. Ethical Leadership in gold with the staff warmly welcome all inquiries negotiations to create a better future gold credit.