Dimming light circuit using parametric solid state relay

The stepless dimmer
lamp circuit using parametric solid-state relay is shown in Figure 48 (a). To understand
the working principle of this dimmer, you must first be familiar with
the working characteristics of parametric solid-state relay. The working characteristics of parameter comrade relays can be divided into positive power drive
, negative power drive and passive power drive according to the driving power. This circuit is a passive power drive. Under passive power
drive conditions, the relationship between the control terminals ①, ②, ③, and ④ pins and the output terminals ⑤ and @ pins is as follows; when
the input impedance of the control terminals ③ and ④ pins When z, (i.e. RI'] + RP2) is less than Lei, the impedance of the output terminals ⑤ and ⑥ is extremely
large, and the voltage drop (U,.) is close to 220V, that is, the parameter solid state relay PSSR is turned off, and the lamp E does not light up at this time. When
the input impedance z between @ and @ pins. ． Greater than z. When , the impedance of the output terminals @ and ⑥ is extremely small, and the voltage drop (U.e) is close to
oV, that is, the PSSR is turned on, and the lamp E lights up normally at this time; when the input impedance between the control terminals ③ and ④ is Z,.
(That is, RPl + RP2) is between 厶 and 磊, and the pressure drop (U5e) of the output terminals ⑤ and ⑥ is
linear , see Figure 48 (Xiu), so the adjustment of (RP]~-RP2) The resistance value can change the output voltage drop U. . The size
is from 『m to achieve the purpose of adjusting the brightness of the electric lamp E.
    The larger value of RFI is used to adjust the initial brightness of the lamp. It is a fine-tuning potentiometer. Once set once, it
will not be adjusted again. RP2 is the brightness adjustment potentiometer, and adjusting its resistance can adjust the Z of PSSR. ;
Continuous change between Zn - Ze can make U. Changes smoothly between 3-2] 5V (actual measurement value), that is, the light brightness
changes smoothly. Since the insulation resistance between the control terminals ①~④ and the output ⑤ and ⑥ pins of the PSSR is
1OOMfl, there is good electrical isolation between the manual barrel photopotentiometer and the mains, making it very
safe and reliable to use. The varistor RV is used to protect I and SSR from the impact of power grid surge voltage.