physics class 12 project on electronic eye

[jaseela123d]

The electronic eye has a lot of use in this electronic age, also known as magical eye. It can be used as an automatic guest indicator on the door, if installed in the lower part of the door entrance. Once it is installed in the door, it is not necessary to install a call ringer. It can also be used in homes or banks as an anti-theft alarm.

Fix the LDR on the wooden door or in a locker to protect it so that when someone tries to open it, a shadow falls on the LDR and the circuit activates and produces a pleasant sound through the buzzer.

This electronic eye circuit uses the NOT gateway of CMOS I.C CD 4049. The CD 4049 contains six independent NOT gates in one package; we have only used one. NO the output of the door goes high (1) when the input pin 3 is at a level lower than 1 / 3rd level of the supply voltage, on the other hand the low output (0) when it is above 1 / 3rd level. Therefore, a small change in pin-2 voltage is sufficient to change the output level (pin-3) from 1 to 0 and from 0 to 1. The output has only two high and low states and can not remain at no intermediate stage. It is powered by a 9V battery for portable use. The circuit is economical in energy consumption. Pin 1 is connected to the positive supply and pin 8 is connected to ground.

To detect the present of an object, we have used LDR and a light source. LDR is a special type of resistance whose value depends on the brightness of the light that falls on it. It has a resistance of approximately 1 megaohm when it is in total darkness, but a resistance of only about 5k ohms when the brightness is illuminated. It responds to a large part of the light spectrum.

We have created a potential splitter circuit with LDR and 220 KΩ resistor connected in series. We know that the voltage is directly proportional to the conductance, so we will get more voltage from this divider when LDR is receiving light and low voltage in the dark. This split voltage is given to the door entry NO.

As soon as the LDR goes dark, the input voltage of the gate does not fall 1/3 of the supply voltage and pin 2 goes high and the LED or the buzzer that is connected to the output is activated.

The advantage of using the logic gate is that the data can be easily sent to another digital interface device, that is, one can easily feed data to the computer using a parallel port or for further processing.