In this project, we will see a simple Home Security application called Electronic Eye Controlled Security System using LDR as the main sensor and a few other components.
Electronic eye is also called magic eye. As the automation is an emerging technology these days, just imagine a door bell that automatically rings when a person visits your home. This also provides security when any person is trying to enter into your home without your permission. Electronic eye is a simple electronic device that continuously watches if anyone is visiting your home.
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Step 1: Required Hardware
The following components have been used:
· 7805 Regulator
· Resistors – 220Ω x 2, 1KΩ x 2, 100KΩ
· 1N4007 PN Diode
· Capacitors – 1µF, 10µF
· Transistors – BC 547 x 2
· Light Dependent Resistor (LDR)
· Connecting wires
· 9V battery
Step 2: Circuit Schematic & Working
This circuit can be divided into two parts. One is the power supply and the other is the logic circuit. In the power supply circuit, a 9V supply from a battery is converted to the 5V .The logic circuit operates the buzzer and an LED when any shadow falls on the LDR.
Power supply circuit consists of battery, diode, regulator and capacitors. Initially a 9V battery is connected to the diode. Diode used here is a simple P-N junction diode of 1N4007 series. In this circuit, 1N4007 is connected in the forward bias condition.
The main purpose of the diode in this circuit is to protect the circuit from reverse polarity i.e. to protect the circuit if by any chance the battery is connected in reverse polarities. So, the P-N junction diode connected in the forward bias allows the current to flow only in one direction and thus the circuit can be protected. There is some voltage drop across the diode. A voltage of 0.7V is dropped across the diode.
A regulator is used for regulating the output voltage of the circuit .The regulator IC used here is 7805. 78 represent the series and 05 represent the output voltage. Thus a voltage of 5V is produced at the output of the regulator. Two capacitors are used before and after the regulator. These two capacitors eliminate the ripples. Thus a constant voltage is produced at the output of the regulator, which is applied to the logic circuit.
Step 3: PCB Design
The above figure shows the PCB design using Eagle software.
Parameter consideration for PCB design
1. Trace width thickness is minimum 8 mil.
2. Gap between plane copper and copper trace is minimum 8 mil.
3. Gap between trace to trace is minimum 8 mil.
4. Minimum drill size is 0.4 mm
5. All the tracks which has current path needs thicker traces.
Step 4: Sending the Gerber to Manufacturer
You can draw the PCB Schematic with any software as per your convenience. Here I have my own design and Gerber file attached. After you generate the Gerber file you can send it to your manufacturer.
Mine is LIONCIRCUITS. They provide high quality boards in the best prices. Also, they have free shipping all over India.
Step 5: Waiting for Fabricated Board From LIONCIRCUITS
I will write part-2 instructable in the coming week after I receive the fabricated board form LIONCIRCUITS.
Till then stay tuned.