In the circuit of the solar panel based charger for the 12v battery, and built in the operational amplifiers LM324 and LM393.The LM324 it consist of high-gain, four-independent, internally frequency compensated operational amplifiers. It is designed specifically to operate of a single power supply over a wide range of voltages. The battery is connected to the solar panel through the diode D1 prevents the battery from discharging to the panel and current-sensing resistor R1.
Voltage Drop across resistor R1 is fed to the non-inverting inputs amplifier N1 through N4 of LM324.The output of the operational amplifier N1 lights up the Light-emitting diode (LED1) and ranges in 0 to50mA. If LED2 and LED3 also glow, the charging current is between 50mA and 100mA. Similarly, LED4 through LED6 also glow, the charging current is between 100mA and 200mA and remaining LEDs also glow, the charging current is above than 200mA. The LM393 consists of two-independent, precision, voltage comparators with low-offset voltage that operate off a single power supply over a wide range of voltage.
The reference voltage of non-inverting pin of comparators N5 and N6 derived using zenerdiode ZD1 and the outputs of the comparator go low and LED11 and LED12 glow. The battery voltage of non-inverting pin of comparators and derived using potential-divider resistors R18 and R19. The circuit of the LED lighting system consist of three white LEDs are connected in series with a 150-ohm current limiting resistor. Totally 18 white LEDs are used in the similar fashion for the lighting system in solar cell.
