6V "Clairvoyance" charger circuit diagram analysis

　　The circuit of the "Clairvoyant" charger is shown in the figure. Among them, the unidirectional thyristor VS1 is the charging current tube of the battery GB, and VS2 is used to cut off the charging current when the battery is charged. When the power is turned on for charging, the relay K is activated, contact 3 is connected to contact 2, the trigger end of VS1 obtains the trigger voltage from R1 and VD4 and is turned on, and the rectified current charges the battery GB through VS1. When the battery GB is charged to the set voltage (for example, 7.2V), VS2 is turned on, causing the potential of the trigger end A of VS1 to be much lower than the cathode potential of VS2, VS1 is cut off, and the battery GB stops charging. The light-emitting tube LED is used for charging display. When the battery charging stops and VS2 is turned on, the LED goes out. The 6V indicator light HL is used to indicate ~220V power outage.