An Automatic LED Emergency Light circuit is designed to turn ON when there is no adequate lighting or if the power supply is cut-off. Earlier fluorescent lights were used to build such circuits. But the use of LEDs has proven to provide adequate lighting for a longer period before draining the battery.
We have developed three circuits under Automatic LED Emergency Light. Two of them are designed by Mr. Seetharaman, a very valuable and important contributor to this website. We have listed the circuits here for your ease of reading. If you have any doubts; please comment on the circuit name or circuit number.
1. Simple Emergency Light Circuit
This is one of the most cost-effective (cheap) and simple emergency light circuit developed for CircuitsToday – This is an automatic emergency lamp with daylight sensing, means it senses darkness/night and turns ON automatically. Similarly, it senses daylight and turns OFF automatically.
We have designed a simple emergency lamp circuit that does not require any special equipment; even a multimeter to assemble and use. Any individual who can do a good quality soldering must be able to build this circuit successfully. This can be easily accommodated in the defunct two 6 watt tube National Emergency Lamp or any PL tube type emergency lamp. The difference will be in the working; it will work non stop for more than 8 hours. Deep discharge is taken care of by the LED characteristic and overcharge protection is taken care of by the fixed voltage regulator. This uses a simple 3-Pin fixed regulator that has a built-in current limiting circuit. The only required adjustment is preset which has to be set to ensure the LEDs just light up (it should be left at that position). The 5mm LDR is just mounted on top of the emergency light as shown in the photograph. LDR is used to avoid it lighting up during day time or when the room lights are ON. 2 LEDs are used in series; the dropping resistance is avoided and 2 LEDs light up with current that is required for a single LED, by which energy is saved to a great extent.
Note: This circuit is developed by Mr.Seetharaman for readers of CircuitsToday. This particular circuit has been kept so simple for people who have limited access to components or in other words, this is an emergency light circuit that you can build with minimum components. In addition to the circuit diagram, He has shared photographs of the prototype he made in National emergency light and a PCB design.
Simple Emergency Light Circuit Diagram:
Photographs of prototype made in National Emergency Light:
Emergency Light Circuit PCB Design:
2. Automatic LED Emergency Light
NOTE: Considering the doubts raised by many of our valuable readers in our Comments section, this circuit has been modified by Mr.Seetharaman, one of our valuable contributors. You can see his modified circuit here: Automatic LED Emergency Light Modified.
This is the circuit diagram of a low-cost emergency light based on a 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 that stops charging when the battery is fully charged.
The IC LM 317 produces a regulated 7 V for the charging of Battery. Transistor BD 140 drives the output. Transistor BC 548 and Zener diode controls the charging of the battery.
It is always better to connect a heat sink with BD 140. Before using the circuit output of LM317 must be set to 7V by adjusting the potentiometer.
Automatic LED Emergency Circuit Diagram:
The most modified and best version for this circuit is intricately explained with a neat circuit diagram and a 2 part explanation. One part is the LED lamp light circuit and the other is the battery charger circuit. All current ratings and voltage ratings are perfectly calculated with basic and clear instructions. A further modified version is also available where under-voltage cut-off protection is provided for the LED emergency light circuit. You can find the circuit here.
We have more interesting Lighting circuits for you, please take a look:
2. Flashing LED Unit – A circuit application to flash many LED’s.
4. Street Light Circuit – Want to build a street light application? This is the one you are looking for.
5. Light Activated Switch – A circuit application to make a switch activated when light falls upon (and vice versa).
When I was in my young days, I always had this desire to build an emergency light application. I’ve successfully built one during my high school days. I hope you enjoyed building these circuits and understood the concepts behind each. I wish you all learn more about electronics from our website. Happy learning days.