Use PSSR to make a gradual brightening and dimming light switch

The gradually brightening and dimming light switch circuit made with PSSR is shown in Figure 3-67. The parameter solid state relay PSSR in this circuit works
in active positive power drive mode.
    The characteristics of the active positive power drive mode are: when the control input terminals 1 and 4 have voltage and current input (lv, lU A),
the voltage drop U56 of the 5 and 6 pins of the PSSR is the power supply voltage 220V, that is, the PSSR is turned off; there is no current When inputting,
the pressure of pins 5 and 6 of PSSR drops to zero, that is, PSSR is turned on. Similar to the curve in Figure 3-64, PSSR also has a linear control section near IV,
so the circuit has a soft-start function.
    In Figure 3-67, SB is a 1×2 toggle switch . The position shown in the picture is the light-off state. Since there is a voltage of about 3V between pins 1 and 2
, and the capacitor CI is also fully charged, the voltage drop of U56 at this time is 220V, that is, PSSR is turned off and light H does not light up. When you need to
turn on the light, you only need to turn SB to position 2. At this time, the charge stored in capacitor C1 will be discharged to resistor R1, causing
the voltage between pins 1 and 4 of PSSR to drop. PSSR soon enters the linear control section, and the voltage of U5b begins to decrease, that is, the voltage across the lamp H begins to rise.
When the Cl charge is basically discharged, Um drops to zero, and the 220V voltage is all applied to both ends of the lamp H, that is, the lamp lights up normally. Glowing,
this is the gradual brightening process of turning on the light. When turning off the light, just turn SB to position l. At this time, G charges CI through R1, causing
the voltage between pins l and 4 of PSSR to rise. PSSR will soon enter the linear control section, and the voltage of US6 begins to rise, that is, the bulb The voltage across H
rises and then falls. When the voltage across Cl is significantly higher than IV, oh 6 rises to 220V, that is, the PSSR is turned off and the light
is completely extinguished. This is the fading process of turning off the light. Adjusting the resistance value of Rl changes the charge and discharge time constant of the capacitor Cl
, so the time of the circuit's fading-in and fading-out process can be adjusted. However, the data shown in the diagram is very suitable and readers do not need to change it.
    Resistor R2 and capacitor C2 form an absorption loop, which is used to protect the PS SR parameter solid state relay.