Measuring positive and negative resistance with a multimeter R × 1k or R × 10k file, DO41 diodes, measuring the diac positive and negative resistance. Normally its positive and negative resistance should be infinity. If the measured positive and negative resistance values ??are very small or 0, it shows that the diode breakdown. Measuring voltage measuring diac turn turning voltage There are three ways. The first method is: the positive electrode (E) and the negative megger (L) were connected to both ends of the bi-directional trigger diode, providing breakdown voltage, line type diode with a Megger, while DC voltage profile with a multimeter measure the voltage, the diac poles reversed measured once again. Compare the bias voltage value of the two measurements (usually 3 ~ 6V). This deviation is smaller, the better the performance of the diode. The second method is: first with a multimeter measure the mains voltage U, and the measured way trigger diode string into the multimeter's AC voltage measuring circuit, the access mains voltage, read voltage value U1, then the diac and read voltage values ??U2 poles reversed after connection. If the voltage value U1 and U2 are the same, but with different voltage values ??U, then the bidirectional trigger diode conduction properties with good symmetry. If U1 and U2 voltage value difference is large, it indicates that the bidirectional trigger diode continuity asymmetry. If U1, U2 voltage values ??are the same mains U, diode, it shows that the diac internally short-circuit damage. If U1, U2 voltage values ??are 0V, the description of the diac internal open damaged. The third method is: 0 ~ 50V continuously adjustable DC power supply, the power of positive series with a 20kΩ resistor after the end of the two-way trigger diode phase, the negative power supply series multimeter current file (which is set at 1mA file) after the two-way trigger the other end of the diode phase. Gradually increase the power supply voltage, a more obvious when the ammeter pointer swing (tens of microamps or more), then this has been a two-way trigger diode turns on, then the power supply voltage that is the breakover voltage of the diac. Figure 4-73 is a bidirectional detection voltage diode turn trigger. Diodes, press forward and reverse characteristics are classified as follows. 1. general use point contact diode This diode as the title puts it, is often used in the detection and rectifying circuit, is a forward and reverse characteristics are neither particularly good nor particularly bad intermediate products. Such as: SD34, SD46,1N34A etc. fall into this category. 2. High reverse voltage point contact diode is high maximum peak reverse voltage and the maximum reverse voltage DC products. For use in high voltage circuit detection and rectification. This type of diode is generally not very good or positive characteristics in general. In the point-contact germanium diodes, there SD38,1N38A, OA81 and so on. Such germanium diode, SMD diode, the pressure is limited. Silicon alloys and diffusion when demanding. 3. High reverse resistance point contact diode forward voltage characteristics and the same general diode. Although its reverse breakdown voltage is particularly high, but the reverse current is small, so the specialty is the reverse resistance is high. Used in high input circuits and high-impedance load resistance of the circuit resistance of the material on germanium diodes high reverse resistance is concerned, SD54,1N54A etc. belong to this type of diode. 4. High point contact diode conduction and high reverse resistance type it instead. Despite its reverse characteristic is poor, but the forward resistance becomes sufficiently small. High point contact diode conduction, there are SD56,1N56A like. High conductivity bond type diode, to be more excellent characteristics. Such diodes, particularly in the load resistance is low, a high rectification efficiency. Reverse diode characteristics of the applied reverse voltage does not exceed a certain range, current through the diode is a minority carrier drift motion of the reverse current form. Since the reverse current is small, the diode is in the off state. The reverse current is also called the reverse saturation current or leakage current, diode reverse saturation current greatly affected by temperature. Generally silicone tube reverse current is much smaller than the germanium tube, reverse saturation current at low power silicon tube nA magnitude, low-power germanium tube μA magnitude. When the temperature rises, heating the semiconductor excitation, a small number of the number of carriers increases, the reverse saturation current increases. Diodes | gold credit | 0.5W Zener provided by Qingdao integrity Technology Co., Ltd. Diodes | gold credit | 0.5W Zener 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 contact phone book pages or pictures on request The latest information, contact: Mr. Yang.