Today we are going to learn how to make a very cheap NiCd battery charger with overvoltage protection or control circuit. This circuit is very much simple and specifically designed for 12V NiCd battery. The charger have current and voltage control at the same time.
Its charging current is around 100mA but we can change it using the formula : (Vd1 - 0.7) / R2 ; where Vd1 is voltage of zener diode D1.
Its Cutoff voltage is limited to Vd2 - 0.7 ; where Vd2 is voltage of zener diode D2
Part List:-
R1 - 2.7 kilo ohms 1/4watt
R2 - 56 ohms 1Watt
D1 - 1N4735A or any 6.2V zener diode
D2 - 1N5244B or any 6.2V zener diode
D3 - 1N4001 or similar diode
Q1 - 9013, 2N2222 or similar NPN transistor
Q2 - 2N3440 or similar NPN transistor
Simply solder the above circuit and enjoy simple 12v 100 mA or change it.
For any further querry please ask them in comment section. I wil be happy to help.
