One of the fade-in and fade-out light switch circuits

The fade-in light switch can make the brightness of the light change slowly when it is turned on and off, and the brightness can be adjusted at will. (1) One of the light switch circuits of
gradually brightening and dimming.     The circuit is shown in Figure 2-35. When the switch SA is closed, the brightness of the lamp changes from weak to strong and lights up; when the switch SA is opened, the brightness of the lamp changes from strong to weak and goes out. Adjust the potentiometer RP to change the brightness of the bulb.     If the values ​​shown in Figure 2-35 are used, the process of the light gradually brightening and dimming takes about 60 seconds. By changing the resistance values ​​of Rs, MA, cl and RP, you can adjust the fade-in and fade-out time. If you want to control a high-power light group, you can choose high-current rectifier diodes and thyristors.