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Magic Eye using 555 Timer IC

Summary

By: 
Anjali Sethiya

     Magic eye can be used as automatic guest indicator in your home. Just install this at the bottom of the door and whenever a person comes at door its shadow will fall on light dependent resistor and will ring the bell. Giving you an indication that somebody is present on the door without the knowledge of the visitor.

     It can also used as a prevention measure against vandalism. So, apart from homes, it can also be used shop and banks.

     So this magic eye circuit can be worked as automatic door bell plus thief alarm.

Magic Eye using 555 IC Timer

Description

This circuit is based on a LDR which act as a sensor to detect the shadow; NE555 is a timer IC and UM66 which is used as melody generator IC.

The circuit woks on the principle of operation of LDR (light dependence resistor). LDR is a device whose sensitivity depends upon the intensity of light falling on it. The resistance of LDR decreases when intensity of light falling on it increases and vice versa (resistance increases when intensity of light falling on it decreases). In dark or in absence of light, LDR exhibits a resistance in the range of mega ohms, which decreases to a few hundred ohms in presence of bright light.
When light is continuously falling on LDR its resistance decreases. Therefore potential difference between pin 2 of IC1 and ground is also low. In this state out pin 3 of IC1 is high. This will make the pin 3 which is the ground terminal also high and IC2 will not conduct and no musical bell sound will be heard.
But when somebody comes on door and its shadow falls on LDR. Then resistance between the pin 2 of IC1 and ground start increasing and output pin 3 of 555 timer goes low. This will provide the ground to pin 3 of IC2 for its operation and melody can be hear. In this circuit transistor T1 is used to amplify the weak signals which will then feed to speaker.
We have used a zener diode at the pin 2 of UM66 because excess voltage more than 3.3V will harm the IC. And with the help of VR1 you can change the threshold operation of the circuit.

Circuit Diagram

Components

Resistor Image
Resistor

Resistor is a passive component used to control current in a circuit. Its resistance is given by the ratio of voltage applied across its terminals to the current passing through it. Thus a particular value of resistor, for fixed voltage, limits the current through it. They are omnipresent in electronic circuits.

...
Capacitor image
Capacitor

Capacitor is a passive component used to store charge. The charge (q) stored in a capacitor is the product of its capacitance (C) value and the voltage (V) applied to it. Capacitors offer infinite reactance to zero frequency so they are used for blocking DC components or bypassing the AC signals. The capacitor undergoes through a recursive cycle of charging and discharging in AC circuits where the voltage and curre...

Potentiometer, Variable Resistor Image
Potentiometer

Potentiometer (Pot) is another class of variable resistors and is used as an adjustable voltage divider. It consists of a fixed resistance track having connections at both ends and a sliding contact, called wiper, which moves along this track by turning the spindle. If only one of the connections and wiper are used, it behaves as a variable resistor or rheostat. In case wiper is not used, it will offer fixed resistance across th...

UM66 | Melody IC Image
IC UM66
 
UM66T is a melody integrated circuit. It is designed for use in bells, telephones, toys etc. It has an inbuilt tone and a beat generator. The tone generator is a programme...
555 Timer | IC 555 | NE555
555 Timer IC

555 is a very commonly used IC for generating accurate timing pulses. It is an 8pin timer IC and has mainly two modes of operation: monostable and astable. In monostable mode time delay of the pulses can be precisely controlled by an external resistor and a capacitor whereas in astable mode the frequency & duty cycle are controlled by two external resistors and a...

Video

Step-By-Step

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Thank you
Team EG

 

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