Unidirectional way thyristor SCR trigger diode characteristic test similarities that have a one-way conductivity, except that the SCR conduction also controlled by the gate voltage. That makes thyristor must have two conditions: should be added between the anode (A) and the cathode (K) forward voltage, the control electrode may be applied between the forward voltage (G) and the cathode (K) . When the thyristor, a gate will lose effect. Unidirectional conducting SCR process is illustrated in Figure 2 shows an equivalent circuit to illustrate: PNP emitter tube quite SCR anode (A), NPN emitter tube quite SCR cathode (K) , base of the PNP and NPN tube collector tube is equivalent to the posterior pole associated thyristor control electrode (G). Way thyristor SCR triggering characteristic test between A, G joins a touch switch (in order to operate), with a multimeter R × 1Ω files, black pen then A very SCR, the red pen then K at this time to add a forward voltage of the SCR (multimeter enclosed by batteries), multimeter pointer does not move, the SCR is not conducting, when you press the switch, A, G turned on, G, K coupled between the trigger voltage thyristor BTA216, SCR was turned on, the multimeter pointer deflection, point to a smaller value; when G, after A disconnected, lost control voltage multimeter pointer if the same position, SCR is still in the conduction state, indicating that the characteristics of the SCR trigger good, if G, after disconnecting A multimeter pointer then deflected SCR BTA140, point ∞. That SCR is not conducting, then the characteristics of the SCR trigger bad or corrupted. SCR BTA216, SCR, are fertile Electronics Dongguan City is provided by Wal-Electronic Technology Co., Ltd. Dongguan City is Wal-Electronic Technology Co., Ltd. (www.dgmydz.com) (www.dgmydz.com) strong, credible, FET and other industries in Dongguan, Guangdong has accumulated a large number of loyal customers. The company better work attitude and constantly improving innovative ideas will lead the electronics are fertile and you hand into the brilliant, for a better future!