We can count up from the cathode of the first, second and third floors to see the surface is an NPN type transistor, but two, three or four layers composed of the other PNP transistor. Wherein the second and third layers of two overlapping common. When between the anode and cathode plus a forward voltage Ea, SCR BT136S-600E, and the gate G and the cathode C between (rather BG1 between the base-emitter) Enter a positive trigger, BG1 will generate base current Ib1, amplified, SCR BT137S-600E, BG1 will have a magnified β1 times the collector current IC1. Way thyristor SCR circuit is 7-1 in place of the relay J, can still be completed Figure 7-1 latch function, which is closed when the switch K1, SCR, the circuit does not work, SCR T435 -600T, L bulb does not light. When touched at K2 when micro switch, SCR power supply voltage through the gate, power-R1 is triggered turned on and the self-locking, L is lit, then K2 no longer work, to make the L goes off, only disconnect K1. Thus, the circuit in Figure 7-2 also has a latch function. SMD SCR | n Waugh electronic (online consultation) | SCR provided by the Dongguan City is fertile Electronic Technology Co., Dongguan City is Wo Electronic Technology Co., Ltd (www.dgmydz.com) (www.dgmydz.com) Dongguan, Guangdong, FET leaders, 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-e-leadership in the positive with the staff warmly welcome all inquiries negotiations to create a positive fertile electronic better future.