This circuit is called the auto circuit which can use any electronic device to operate it automatically. To make this circuit the cost is very low. Any interested student can make it very easily. The main component of this circuit is transistor. Its operation is very easy.
The main purpose of this is to operate a charger fan where need 6volt battery. This circuit is mainly needed when the main power is OFF. That is called load shedding. Because at the time of load shedding , 6volt battery operate the fan automatically. You don’t have need to ON the switch of the fan or OFF the fan switch. Only relay work this as a switch. The charging system is also automatically. On the other big matter is that no over charge is occurred of the battery. So the life time of the battery is increased.
1. Transistor ( npn ) – 2N2222, BC547
2. Zener Diode - 6.8V
4. Relay - 6V
5. Resistor – 1K, 100Ω
6. Rechargeable Battery - 6V
7. Fan - 6V
8. Power supply - 6V
This circuit is three section, input section and output section. 2N2222 transistor is used to control relay. BC547 transistor is used to control output section using relay. Zener diode and a diode connect with BC547 transistor base as a series connection. Zener diode always controls battery charge. It zener voltage is 6.8V which can’t overcome battery voltage.
When power supply voltage is applied to the 2N2222 transistor base the transistor is on. So the relay is ON relatively the output circuit is OFF. Inverse will occurs when power supply voltage is OFF. When 2N2222 transistor is ON then relay active only battery charging, relay deactivate the fan. Zener diode always keeps battery voltage full (6volt).
1. Need not switch ON/OFF.
2. It depends on AC power supply come or gone.
3. This circuit is used when you are sleeping.
4. Easy to make
5. Cost is very low
6. Components are few.
7. Battery can’t over charge.
8. Overall efficiency is 78%.
9. Not you, only relay can do your work.
10. The circuit is a small project for all students.