A) ordinary diode testing (including the detector diodes, rectifier diode, damping diodes, switching diodes, freewheeling diode) is a PN structure into a semiconductor device having a one-way electrical properties. By detecting its positive and negative resistance value with a multimeter, it can distinguish the diode electrode, but also estimate the diode is damaged. 1. Polarity discrimination would multimeter R × 100 R × 1k file or files, two tables document the two electrodes respectively connected diodes, measure a result, the swap two tables document, and then measure the result. The results of the two measurements, DO35 diode, once measured large (reverse resistance) resistance, a measure of the resistance is small (for the forward resistance). In the lower value measurement, the black pen then the diode cathode, the red pen then the negative diode. 2. Single negative conductivity detection and the quality of judgment generally, germanium diode forward resistance value of about 1kΩ, reverse resistance value of about 300. Silicon diode resistance value is approximately 5 kΩ, negative resistance value is ∞ (infinity). Forward resistance the smaller the better, the bigger the better reverse resistance. Positive and negative resistance values ??differ more poor, DO41 diode, indicating a one-way diode better electrical properties. If the positive and negative resistance values ??were measured diode close to 0 or less resistance, it shows that the diode has a breakdown of internal short circuit or leakage damage. If the measured diode positive, negative resistance values ??are infinite, then the diode is open corrupted. 3. Reverse breakdown voltage detector diode reverse breakdown voltage (voltage value) to test meter to measure the transistor DC parameters. The method is: When measuring diode, should the test table "NPN / PNP" selection key is set to NPN state, diode, diode within and then tested positive then the test table "C" jack, insert the negative test table "e" jack, then press the "V (BR)" button, the test table to indicate the diode reverse breakdown voltage. Also available megohmmeter and a meter to measure the diode reverse breakdown voltage measurement tested positive phase diode cathode and megger, the cathode of the diode is connected to the positive and megger, but with a multimeter (set ) voltage to an appropriate DC voltage profile across the monitor diode. As shown in Figure 4-71, shake megger handle (should slow gradually speed up), the voltage across the diode to be stable and no longer rises, the voltage value that is the diode reverse breakdown voltage. Diode voltage drop: a silicon diode (non-light emitting type) forward voltage drop of 0.7V, germanium tube forward voltage drop of 0.3V, light-emitting diode forward voltage drop will vary with different emission colors. There are three main colors, the specific reference values ??drop as follows: red light-emitting diode voltage drop 2.0--2.2V, yellow light-emitting diode voltage drop of 1.8-2.0V, a green light-emitting diode voltage drop of 3.0-3.2V, normal Rated current emits light approximately 20mA. 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, in-line diode PN junction capacitance is small, suitable 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. Diodes | gold credit | SOD80 diode provided by Qingdao integrity Technology Co., Ltd. Diodes | gold credit | SOD80 diode is Qingdao integrity Technology Co., Ltd. (www.qdjcx.com) this year introduced a new upgrade, the above picture is for reference only, please call the telephone or pictures on this page, for the latest information Contact: Mr. Yang.