How to use single-junction transistor SCR trigger circuit it? RB1 base resistance decreases rapidly, the capacitor C discharges rapidly through the PN junction of resistors R1 to SCR T405-800T, so that the voltage across R1 Ug a positive transition occurs, forming a steep leading edge [Figure 8 (b)]. As the capacitor C discharges, UE decline exponentially until below the valley voltage UV single-junction transistor is turned off. Thus SCR T405-600T, across R1 trigger pulse output is the steeple. In this case, the power UBB began to charge the capacitor C, into the second charge-discharge process. This cycle, the circuit engaged in periodic oscillations. RP can be changed to adjust the oscillation cycle in the waveform controlled rectifier circuit, found within the forward voltage of the thyristor to withstand every half cycle SCR, issuing the first time the trigger pulse are the same, that is, the control angle α and the conduction angle θ are equal, then the single-junction transistor relaxation oscillator exactly how to cooperate with the AC power supply in order to achieve effective control of it? When the AC voltage zero-crossing instant, SCR VS forced shutdown, relaxation oscillator energized, they began to charge the capacitor C, repeat the process. Thus, each time after AC voltage zero crossing, the first issue of a relaxation oscillator trigger the same time SCR 2P4M, this time depends on the resistance of RP and C capacitance. Adjusting the resistance of RP, can change the charging time of the capacitor C, the first time it changed Ug issued, a corresponding change of the control angle of the thyristor, so that the average value of the output voltage across the load RL is changed, to achieve the purpose of the regulator. SCR T405-800T, 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!