Automatic emergency light

Automatic emergency light  

Hello friends today we are going to build a simple auto emergency light using some few components. 

Component needed are as follows:

RESISTORS

  1k  2pcs

  2.2k  2pcs

  10k 3pcs

  10R (ohms) 2pcs

  4.7k   1

  LDR   1

CAPACITORS

1000mf   1

100mf     2pcs

TRANSISTORS

BC547  2PCS

INTEGRATED CIRCUIT (IC) 

NE555 OR LM555

TRANSFORMER

Step down 220/12volt 1

DIODE 

1N4007

LED

white 9pcs, with 1 red 

BOARD 

vero board or good pcb

SWITCH
Normal close 1

BATTERY 

See text

CIRCUIT DIAGRAM:

In the cct diagram above you can replace R5 with 10k potential meter 10k pot(code 103),  to enable you to adjust the light dependence resistance (LDR) in such a away that it can be able to sensed the day and the night to activate the light emitting diodes (LED) 

How it works 

The hart of the circuit is the NE555 , pin 8 is the VCC (+) while pin 1 is the GND (-) The LDR and R5 where connected in voltage divider send to pin 2,pin 6 from the point of connection. pin 2 and pin 6 were

connected to monitor when their is ⅔ volt across the point of LDR and R5, pin 3 is the output which send a high/low signal to the Bc547 to turn the light ON or OFF,  Pin4 is the reset which off the entire sectary when the  pin is connected on GND ( -)

When there is a public mains it sense it through the R1, which activate the Q4, Q4 will now send a negative signal to pin 4 which is the reset  pin of the IC the light will now shut down automatically,  it happens vice versa

The battery is a rechargeable battery that may be 3.7volt or 7.3volt with a good capacity
Example a portable DVD player battery 7.3volt / 2000mA

It had a good volt and current, but you can also double both in parallel or in series in *parallel current increase
*series voltage increase.


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