This is a 12v battery level indicator circuit using BC 547 NPN transistor. The circuit will work fine using the 12 volt Lead acid battery. With few components and connections only needed for working this entire circuit. The complete circuit working, Diagram and components details are included here.
12v Battery Level Indicator Circuit Diagram
Components Required
- BC 547 NPN transistor – 1
- 11v Zener diode – 1
- 8.2v Zener diode – 1
- LED – ( Red and green )
- 470 ohms 1/4 watt resistor – 2
- 1K resistor – 2
Working
The circuit working based on a NPN transistor. The circuit will indicate if the battery voltage is less than 12v or over 12v DC. Then the led light will change glowing its color in different situation.
The green led is connection to the 8.2v Zener diode. When 12 v is reached the zener diode will passes the voltage and the green LED will turn on.
In that same time Red LED will turn off. The 11v Zener diode will conduct the voltage and the BC547 transistor will turn on and its start to conduct.
Passing negative voltage to the positive pin of the RED LED in that time red LED turn off.
