SCR principle When the anode A side with a positive voltage, BG1 and BG2 tube pipe are in the enlarged state, this time, from the control electrode G a positive trigger signal input, BG2 tube there ib2 base current flows before, the current flowing through the pipe to the collector BG2, enlarged to ic2, ic2 = β2ib2, ic2 along the circuit flow to the base of the pole tube BG1 SCR 2P6M, so there ib1 = ic2, flows through BG1 tube, arriving at the collector current changes ic1, ic1 = β1ib1 = β1β2ib2, this current also flows back BG2 base SCR C106G, making ib2 increased to ib2 = ic1, thus forming a positive feedback loop so that the current surge, so SCR reach saturation and conduction. SCR is turned on and off only two states, with the switching characteristics, changing its status there are some prerequisites. Transition from the off state to a conduction state, the anode potential is always higher than required to meet the cathode potential, and the control electrode have sufficient forward voltage and current; while maintaining the conductive state, must satisfy the anode potential is higher than the cathode potential, and 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. Unidirectional SCR trigger characteristic test between A, K plus allowable forward voltage, two tubes are not conducting thyristor BTA225, this time between when the G, K with a positive voltage will forming a control current flows into the base electrode of SCR V2, and so on until two full conduction. When turned on, even if Ig = O, there is a base current due to V2, and is much larger than Ig, and therefore the two tubes are still turned on. For conducting thyristor off, A, K forward voltage must be reduced to a certain value, or vice versa, or disconnected. The conductive properties of the SCR can be used to test multimeter resistance profile. For low-power thyristor can figure 3 (a) joins the circuit shown, SCR BTA412Y_ are fertile Electronics (certified) _ SCR Dongguan City is provided by Wal-Electronic Technology Co., 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. You can also access (www.dgmydz.com/supply_details_41645395.html), for more information about the company.