2. UZAIR
AHMAD
Principle:
The main principle of the circuit is to
ring the door bell when there is any person at
the entrance. Light on the LDR
determines whether a person is present or not.
When there is any object at the entrance, LDR
is in dark and buzzer starts ringing and the LED
starts glowing.
Components :
7805 regulator U1
ResistorsR1,R2,R3,R4,R5-
1N4007 diode D1
4. PINS OF 7805 IC :
7805 IC have Three pins :
1.INPUT
5. 2.GROUND
3.OUTPUT
PINS OF 7805 TIMER :
INPUT :
In this pin of the IC positive unregulated
voltage is given in regulation.
GROUND :
In this pin where the ground is given. This
pin is neutral for equally the input and output.
OUTPUT :
The output of the regulated 5V volt is taken
out at this pin of the IC regulator.
Working
Initially, connect the on the bread board.
6. Now connect the supply voltage of 9v using
battery.
Place the Light Dependent Resistor in light.
You can observe no sound is produced from
the buzzer.
Place the LDR in dark buzzer starts ringing.
LED connected to the buzzer also starts
blinking.
As the intensity falling on the LDR increases
sound produced by the buzzer increases.
Advantages :
1.This can be used in door bell circuits.
7. 2.This can be used in garage door opening
circuits.
3.Electronic eye can be used in security
applications
4.Easy replacement as it is more economical to
replace them than to repair them.
5.Greater ability of operating at extreme
temperatures.
SCHEMATIC CAPTURE