SCR principle When the anode A side with a positive voltage, BG1 and BG2 tube amplification tubes are in a state of SCR, this time, from the control electrode G a positive trigger signal input, BG2 tube base there ib2 current flows, the current flowing through the pipe to the collector BG2, enlarged to ic2, ic2 = β2ib2, ic2 along the circuit flow to the base BG1 tube pole, so there ib1 = ic2, flows through BG1 tube to reach the collector, the current becomes ic1, ic1 = β1ib1 = β1β2ib2, BG2 this current flows back into the base, so that ib2 increased to ib2 = ic1, thus forming a positive feedback loop so that the current surge, it is saturated and the thyristor is turned on . SCR is turned on and off only two states, with the switching characteristics, changing its status there are some prerequisites. SCR changes from the off state to a conduction state T405-600T, must meet the cathode potential is always higher than the anode potential, and the control electrode have sufficient forward voltage and current; when maintained in the ON state, the anode potential must meet higher than the cathode potential, and the anode current is greater than maintaining the current; transition from conduction state to the OFF state, the need to meet the anode potential is lower than the cathode potential, or anode current is less than the holding current. Way thyristor SCR polarity determination is made of a semiconductor material constituting the three PN junctions, their basic structure, and the equivalent circuit symbols. SCR has three electrodes: the anode (A), cathode (K) and control electrode (G). From the equivalent circuit, between the anode (A) and the control electrode (G) are the two opposite polarity in series PN junction between the control electrode (G) and the cathode (K) is a PN junction. According to the one-way electrical properties of the PN junction, the pointer to select the appropriate multimeter resistance profile SCR 2P4M, tested positive and negative resistance between poles (same poles, will lead the two exchanged measured resistance value) SCR C106G, For the pros and cons of a normal SCR, G, K a big difference between the resistance; G, K, respectively, and the positive and negative A small difference between the resistance and the resistance are great. This test result is only, according to this uniqueness can determine the polarity of the thyristors. SCR 2P6M, are fertile Electronics (certified), SCR provided by the Dongguan City is Wal-Electronic Technology Co., Ltd. Dongguan City is Wal-Electronic Technology Co., Ltd. (www.dgmydz.com) (www.dgmydz.com) is Dongguan, FET leader, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, the maximum limits to meet customer needs. Wal-electronics leader in the positive with the staff warmly welcome all inquiries negotiations to create a positive future Wal-electron better.