Discrimination thyristor (SCR) SCR pin pin determine the following manner: first block with a multimeter to measure the resistance between the R * 1K tripod SCR BTA412Y, the resistance of small feet were a control electrode and cathode, anode remaining foot. Then multimeter R * 10K block, with fingers anode and the other foot, and do not let the feet touching, black pen then the anode, the red pen then the rest of the foot, such as the swing to the right hands SCR BTA216 , indicating that the red pen for the connected cathode-gate was not swinging. Triac structure principle and application of typical applications Triac can be widely used in industry, transportation, household appliances and other fields, to achieve AC voltage regulator, motor speed, AC switch, automatically turn on and off street lights, temperature control, lamp dimmer, stage dimming functions, it is used for solid state relays (SSR) and solid-state contactor circuit. Figure 5 is a proximity switch circuit constituted by Triac. R is the gate current limiting resistor, JAG dry reed pipe. JAG usually off thyristor BTA212, Triac TRIAC is also turned off. Only when a small magnet when JAG pull closer, so that two-way thyristor, the load power is turned on. Due to the current through the reed is very small, only a few microseconds of time, so life is very long thyristor switch BTA140, 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.