Flashing Light Controller (1)

The circuit of the flashing light controller is shown in Figure 1-38.     Experienced readers may find that this circuit is very much like a thyristor stepless dimmer, which is indeed good. If you remove the large capacitor C2 in the circuit, it is a voltage regulator . Now due to the existence of the large capacitor C2, its charging time is longer after the power is turned on. When the voltage at both ends of C2 is charged to a certain value, C2 discharges to the gate of the thyristor vs through R2, turning on vs and the light. Just light up. When the alternating current crosses zero, vs is blocked, the light goes out, and C2 starts charging again, forming an ultra-low-frequency oscillation over and over again, and the light flashes one after another. The flickering frequency of the circuit is mainly determined by the time constant of R2 and C2. According to the data shown in the figure, the lamp H is on for 2 seconds. Turn off for 2 seconds. If you want to speed up the flashing frequency, you can reduce the resistance of resistor R2, but do not change the value of capacitor a. Reducing the resistance of resistor R3 also affects the flashing frequency.