How to Make 1.2V Battery Charger

AA batteries are widely used in portable power tools, photography equipment, flashlights, toys, emergency lighting, hobby R/C, and portable electronic devices. The problem with standard AA batteries is that we need to replace them when they discharge which sometime become costly the solution for that is to use rechargeable AA batteries. By using a suitable battery charger, rechargeable batteries can be recharged over and over again, this makes rechargeable batteries an inexpensive solution to power up our portable devices. Good battery chargers can be very expensive and sometime good chargers are not easily available so we have designed an automatic AA battery charger which works flawlessly and it is very inexpensive so below are the steps to build the charger.

Step 1:

We have used LM393IC as a voltage comparator and we have given a reference voltage to its inverting input which is its pin number 2.we have used a diode and a 10k resistor to make a voltage divider this divider makes 0.6 volts which is given as reference we have used a 5k trim pot as a voltage divider this will divide battery voltages and these voltages are given to non-inverting input of the competitor which is its pin 3.we have used a BC557 transistor as a switch at the output of the comparator so when the battery is fully charged the comparator turns off the transistor and the circuit stops charging the battery that will protect the battery from being overcharged the charger has two leds the red led is turned on when the battery is being charged and when the battery is fully charged the green led is turned on.

Components:
Circuit Diagram:
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