Automatic battery charger circuit in the figure below is the type of battery charger with pulse system and were able to identify the position of a full battery. Automatic battery charger circuit can be used for AA battery charger or another battery. This battery charger circuit can be supplied with 12 volt DC voltage source of power supply. Automatic battery charger circuit is designed with a simple digital and analog components. Automatic battery charger circuit is composed of several parts of the pulse generator serves as a charger (CD4011 CMOS IC), a full battery level detector in charge (IC LM741 comparator), power charger (transistor BD139) and charger indicator (green and red LED). And a complete range of data components used to build an automatic battery charger circuit can be seen in detail in the following figure.
Automatic Battery Charger Schematic
Automatic battery charger circuit on the battery charging process with the system are generated by an astable multivibrator circuit IC2 CD4011 NAND Gate.
The process of charging the battery using the battery charger circuit automatically above monitored by IC LM741 voltage comparator circuit which serves to detect the charged battery voltage level and compares the reference voltage comparator. Reference voltage comparator circuit is determined by the resistor R1 and R2. to get the full battery voltage reference value in accordance with the wishes of the R2 can be changed using the VR 10kOhm. For charging AA batteries comparator reference voltage (the voltage at pin 3 of IC1 LM741) is set to 1.47 volts DC using R2 (VR 10 kOhm).
Battery charging process performed by the BD139 transistor Q1 which functions as a power charger on the battery charger circuit above.
Automatic battery charger schematic is equipped with 2 indicators are indicators of the process of charging the battery using the green LED will light up during the charging process and will be on when charging is complete. Then the red LED battery level indicator is full, where the LED will light when the battery is full and turns off when the charging process is running.