AUTOMATIC EMERGENCY LIGHT

This is automatic emergency light used in night at emergency time when the power cut or off by some region. This emergency light takes 230V AC and it converts it in 12V DC and charge the battery which is used in this circuit. The power of the battery is used that time when the power is cut off or we need to use it. This light is used mostly in villages because there is the lack of electricity is provided.

 In this circuit I use BD 140 transistor the advantage of this emergency light is that if we Use this emergency light in a room no other light source is required but in other emergency light we use another light source when the power is available.

BLOCK DISCRIPTION

First the power supply is given 230 through the step down transformer, the transformer convert it into 12V 1A but it is not gives dc so rectifier is used in it to convert it into dc. For filter the signals in the circuit a capacitor is used on it which filter the signals and convert it into pure DC. It also charged the battery when the power is given in the circuit. A transistor is used to maintain the power supply regularly and the control units (Zener diode) it maintain the zener  voltage and also used it as a switch in reverse biased  condition after that battery is the second power supplier which charged first and give backup power when the main power is cut off. 

CIRCUIT DESCRIPTION

 This is the circuit diagram of low cost emergency light based on white LED. The white led provides very bright light which turns on when the mains supply is not there. The circuit has an automatic charger which stops charging when the battery is fully charged. Here 230v is converted into 12v using step down transformer. Bridge rectifier is used to convert AC input to DC supply. Capacitor is used to filter the input AC supply. When the main supply is ON the charged capacitor voltage is much greater than the battery voltage which keeps the transistor T1 & T2 in reversed biased. As soon as the main supply fails or removed the capacitor voltage becomes lesser as compared to battery voltage. This puts both transistor T1 and T2 in forward biased and the LEDs will glow with the battery voltage. 

Uses

1.   Convert 120V-230V Ac into 12V Dc and charge the battery.

2.   Use in that places where the power doesn’t supply properly.

Advantages

•  Saves fuel.
• Pollution free.
• Easy to use.
• Very low cost under Rs(200-300)
• Easy to install anywhere.

Disadvantages

•  It can be used only for short period.
• Delectated circuit.