Automatic power-off nickel-cadmium battery charger circuit diagram

This circuit uses a simple timer. When charging, four nickel-cadmium batteries with a capacity of 500mA each are connected in series. After the battery is charged with a constant current of 50mA for 15 hours, the circuit is automatically cut off and charging stops. The circuit uses 555 as the clock circuit, which generates a square wave with a period of 6 seconds to trigger IC2. IC2 is connected into an 8192:1 frequency divider. When charging, transistor T1 is turned on, causing relay RL1 to close, and the LED lights up to indicate that charging is in progress. After 555 sends the clock pulse from IC2 to 8192, pin 3 of IC2 becomes high potential, T1 is cut off, RL1 is released, and the circuit stops charging. When starting to charge, press switch S1 to cause the relay to automatically close and charge until the predetermined time.