Friday 22 August 2014

LED EMERGENCY LIGHT

Simple LED Emergency Light Circuit




The article depicts an exceptionally basic natively constructed crisis light circuit that can be utilized amid power disappointments and outside where whatever other wellspring of power may be inaccessible. The circuit utilizes LEDs rather than radiant light, accordingly making the unit extremely power proficient and brighter with its light yield. Additionally, the circuit utilizes an exceptionally imaginative idea particularly contrived by me which further upgrades the practical element of the unit. 

We should take in the idea and the circuit all the more nearly: 

The idea: 

We realize that LEDs oblige a certain settled forward voltage drop to end up lit up and it is at this rating when the Drove is grinding away's best, that is voltages which is around its forward voltage drop encourages the gadget to work in the most proficient way. 

As this voltage is expanded, the Drove begins drawing more present, rather dispersing additional current by getting warmed up itself furthermore through the resistor which likewise gets warmed up during the time spent constraining the additional current. 

In the event that we could keep up a voltage around a Drove close to its evaluated forward voltage, we could utilize it all the more proficiently. That is precisely what I have attempted to settle in the circuit. 

Since the battery utilized here is a 6 volt battery, implies this source is a touch higher than the forward voltage of the LEDs utilized here, which adds up to 3.5 volts. The additional 2.5 volts rise can bring about extensive dispersal and loss of power through warmth era. 

Along these lines I utilized a couple of diodes in arrangement with the supply and verified that at first when the battery is completely charged; three diodes are viably changed in order to drop the overabundance 2.5 volts over the white LEDs (on the grounds that every diode drop 0.6 volts crosswise over itself). 

Presently as the voltage of the battery drops, the diodes arrangement are decreased to two and along these lines to one verifying just the fancied measure of voltage achieves the Drove bank. 

Along these lines the proposed basic crisis light circuit is made exceptionally effective with its present utilization, and it gives reinforcement to an any longer time of time than what it would do with normal associations.




Efficient, Automatic, White LED Emergency Light Circuit Description:


Referring the shown simple LED emergency light circuit, we see that the circuit is actually very easy to understand, let’s evaluate it with the following points:

The transformer, bridge and the capacitor forms a standard Power supply for the circuit. The circuit is basically made up of a single PNP transistor, which is used as a switch here.

We know that PNP devices are referenced to positive potentials and it acts like ground to them. So connecting a positive supply to the base of a PNP device would mean grounding of its base. Here, as long as mains power is ON, the positive from the supply reaches the base of the transistor, keeping it switched off. Therefore the voltage from the battery is not able to reach the LED bank, keeping it switched off.
In the meantime the battery is charged by the power supply voltage and it’s charged through the system of trickle charging.

However, as soon as the mains power disrupts, the positive at the base of the transistor disappears and it gets forward biased through the 10K resistor.

The transistor switches ON, instantly illuminating the LEDs.

Initially all the diodes are included in the voltage path, and are gradually bypassed one by one as the LED gets dimmer.

HAVE ANY DOUBTS? FEEL FREE TO COMMENT AND INTERACT.

Parts List for the proposed LED emergency light circuit

R1 = 10K,
C1 = 100uF/25V,
D1, D2 = 1N4007,
D3---D6 = 1N5408,
T1 = BD140
Tr1 = 0-9V, 500mA,
LEDs = white, hi-efficiency, 5mm,
S1 = switch with three changeover contacts.


Because of the recommendation of one of our eager perusers, the above programmed Drove crisis lightcircuit has been changed and enhanced with a second transistor stage consolidating a LDR trigger framework. The stage renders the crisis light activity inadequate amid day time when adequate surrounding light is accessible, consequently sparing valuable battery power by maintaining a strategic distance from superfluous exchanging of the unit.



Circuit modifications for operating 150 LEDs, requested by SATY:



Parts List for the modified emergency light circuit

R1 = 220 Ohms, 1/2 watt
R2 = 100Ohms, 2 watts,
RL = All 22 Ohms, 1/4 watt,
C1 = 100uF/25V,
D1,2,3,4,6,7,8 = 1N5408,
D5 = 1N4007
T1 = AD149, TIP127, TIP2955, TIP32 or similar,
Transformer = 0-6V, 500mA


The accompanying circuit demonstrates how a low voltage cut off circuit can be incorporated in the above configuration for keeping the battery from getting over released. 

Power Supply Circuit with Crisis Reinforcement 

The circuit demonstrated underneath was asked for by one of the perusers, it is a power supply circuit which stream charges a battery when air conditioning mains is accessible, furthermore bolsters the yield with the obliged DC power through D1. Presently, the minute air conditioning mains falls flat, the battery in a split second goes down and the repays the yield disappointment with its power by means of D2. 

At the point when info Mains is available, the redressed DC goes through R1 and accuses the battery of the sought yield current, additionally, D1 exchanges the transformer DC to the yield for keeping the heap exchanged on at the same time. 

D2 stays converse one-sided and is not ready to direct in light of higher positive potential delivered at the cathode of D1. 

However when mains air conditioning falls flat, the cathode capability of D1 gets to be lower and along these lines D2 begins leading and gives the battery DC move down in a split second to the heap with no interferences.


Parts List for an emergency light back up circuit


All Diodes = 1N5402 for battery up to 20 AH, 1N4007, two in parallel for 10-20 AH battery, and 1N4007 for below 10 AH.

R1 = volt/charging current (Ohms)

Transformer Current/Charging current = 1/10 * batt AH

C1 = 100uF/25


Using NPN transistors



The first circuit can be also built using NPN transistors, as shown here:

circuit is in working, checked !

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