Bidirectional thyristor dimming circuit diagram

The picture shows the bidirectional thyristor dimming circuit diagram . Its working principle is: turn on the power, 220V charges C23 through the bulb VR4 R19... Since the voltage at both ends of the capacitor cannot change suddenly... charging takes a certain amount of time. ..The charging time is determined by the size of VR4 and R19...The smaller it is, the faster it will charge...The larger it will be, the slower it will charge...When the voltage on C23 is charged to about 33V...DB1 can be turned on...can The thyristor is also turned on... After the thyristor is turned on... there is current flowing through the bulb... the bulb lights up... as DB1 is turned on... the voltage on C23 is completely discharged... .DB1 cuts off again...the thyristor also cuts off...the light bulb goes out...the same cycle starts again on C23...because the time is short and the human eye has a lingering phenomenon, so the light bulb looks like If it is always on, the shorter the charge and discharge time...the brighter the bulb will be, and vice versa...R20 C24 can protect the thyristor...If it is used on a resistive load, it can be omitted. If it is used on an inductive load, such as It is said that it must be added to the motor. This circuit can also be used for motor speed regulation.