Design of Automated Light for Bed Room

Well you might have heard of the automated lights but you may not have seen such lights before. The project is regarding making a do it your own design of an automated light for the bed room of your house. The light will switch ON and OFF without your efforts. Yes, it is definitely possible to make a light which would get ON and OFF itself whenever you would enter in to the room and it would switch off when you leave the room. This project is going to be a small part of the automated home system if you are ever interested to make your entire home autonomous i.e. operation of all electrical equipment itself. The automated light could merely be made with the help of an operation amplifier and a timer along with a lamp or bulb.

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List of Components Required for the Project

The following is the entire list of components that you would need to make the project.

1.Resistors of different values (70K, 10K, 50K, and 5K).

2.Capacitors of different values (470uF and 0.01uF).

3.IC of Operational Amplifier i.e. LM741.

4.An IC of timer i.e. IC555.

5.A transistor.

6.A bulb or Lamp of 12 Volts.

7.Wires for circuit completion.

 

Simple Block Diagram

The following is the simple block diagram of the circuit.

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Working of the Circuit and Schematics

The IC of the operational amplifier is having 8 pins in which pin 2, 3 are for the inputs, whereas the pin 3 is for the non-inverting input and pin 2 is the inverting input terminal. The pin 3 is given with a fixed voltage with the help of a potential divider whereas at the pin 2 input voltage is given through the switch. Now the switch is being used in the closed position i.e. SPST switch is being used. Now the output of the operational amplifier is being fed to the IC of timer i.e. 555 which when triggers generates a very low voltage at the input terminal 2 and is also generating a high pulse at the terminal 3 of the OP AMP IC. Now the output of the operational amplifier is then connected to the lamp of 12 volts.

 

The basic circuitry or schematic diagram of the project is as follows.

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As it is evident from the schematic diagram that the switch must be placed over the wall of the room in a way such that when the door of the room is opened, the light gets ON automatically when the trigger of the switch is pushed. When the trigger of the switch is pushed, the connection through switch is completed and it gets ON. The IC of the operational amplifier is working as a comparator by the time when the switch is opened, the inverting terminal of the OP AMP IC is connected to the lamp and a voltages of almost 4 Volts are generated which are fed in to the non-inverting terminal of the OP AMP IC.

 

Now at the non-inverting terminal of the OP AMP IC, the voltage is lesser than that of the inverting terminal of the IC, therefore a novel pulse is being generated at the output of the IC which is fed in to the 555 timer IC with the help of a potential divider arrangement. By this time the IC of 555 timer is getting triggered with the help of low voltage signals at the input side and in return it generates a very high pulse at the output terminal. Now the timer is working in the mode known as mono-stable mode. Here when the lamp is receiving a signal of 12 volts, it glows automatically.

 

Now when you are coming out of the room, you will definitely close the door and the entire process will happen in reverse. Basically the switch would get back in to its original position and would get close. This is because the non-inverting terminal of the operational amplifier IC is getting higher voltages in comparison to the inverting terminal. This ends up in failing the trigger to get ON and the lights don’t get 12 volts and is made OFF.

 

The PCB Design of the Circuit

The basic layout of the Printed Circuit Board for the project is given as below.There are numerous methods which can be used for making the Printed Circuit Board for the project. However, WellPCB is a good choice of printed circuit board manufacturing.

 

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