Smart light
Have you ever wondered how street lights automatically turn on the street?
This is the core principle of a light system.
Adivated switch, An electronic circuit that responds to changes in light intensity
LDR
Principle of operation
Components
Light dependent resistor is a type of variable resistor which is made from semi-conductor materials and relies on the property of photo conductivity
How
Does
It
Work?
In light:
When photons of light strike the material. they are absorbed by electrons. If the photon’s energy is sufficient; it gives the electrons enough energy to jump from the valence band to the conduction band. The increase of free electrons number means an increase in electrical conductivity.
In darkness:
Electrons in the semi-conductor material are tightly bound in the valance band, The number of free electrons is very small in the conduction band, The result is a very high resistance.
LDR
Principle of operation
Components
Light dependent resistor is a type of variable resistor which is made from semi-conductor materials and relies on the property of photo conductivity
How
Does
It
Work?
In light:
When photons of light strike the material. they are absorbed by electrons. If the photon’s energy is sufficient; it gives the electrons enough energy to jump from the valence band to the conduction band. The increase of free electrons number means an increase in electrical conductivity.
In darkness:
Electrons in the semi-conductor material are tightly bound in the valance band, The number of free electrons is very small in the conduction band, The result is a very high resistance.
LDR
Principle of operation
Components
Light dependent resistor is a type of variable resistor which is made from semi-conductor materials and relies on the property of photo conductivity
How
Does
It
Work?
In light:
When photons of light strike the material. they are absorbed by electrons. If the photon’s energy is sufficient; it gives the electrons enough energy to jump from the valence band to the conduction band. The increase of free electrons number means an increase in electrical conductivity.
In darkness:
Electrons in the semi-conductor material are tightly bound in the valance band, The number of free electrons is very small in the conduction band, The result is a very high resistance.
LDR
Principle of operation
Components
In light:
The LDR’s resistance is low, the result is a low output voltage from a voltage divider, so the transistor stay “off”, so the LED doesn’t light up and the relay stay “off” and doesn’t switch on the lamp.
In darkness:
The LDR’s resistance increases, the result is a high output voltage from the voltage divider, which turns the transistor “on” to allows current to flow, so the LED lights up and the relay is turns “on” and switches on the lamp.
LDR
Principle of operation
Components
In light:
The LDR’s resistance is low, the result is a low output voltage from a voltage divider, so the transistor stay “off”, so the LED doesn’t light up and the relay stay “off” and doesn’t switch on the lamp.
In darkness:
The LDR’s resistance increases, the result is a high output voltage from the voltage divider, which turns the transistor “on” to allows current to flow, so the LED lights up and the relay is turns “on” and switches on the lamp.
LDR
Principle of operation
Components
In light:
The LDR’s resistance is low, the result is a low output voltage from a voltage divider, so the transistor stay “off”, so the LED doesn’t light up and the relay stay “off” and doesn’t switch on the lamp.
In darkness:
The LDR’s resistance increases, the result is a high output voltage from the voltage divider, which turns the transistor “on” to allows current to flow, so the LED lights up and the relay is turns “on” and switches on the lamp.
LDR
Principle of operation
Components
Transistor “BDW93”
We can use this type of electronic components as a switch. It amplifies a small signal to control a larger signal. In this circuit: when the LDR senses darkness, the transistor turns on and allowed current to flow to the relay and activate the lamp.
LDR
Principle of operation
Components
Resistor 220 Ω
This is a small component which limits electric current to protect other parts in the circuit. In this circuit, it is used in the LED indicator circuit to prevent the LED from burning from high currents.
LDR
Principle of operation
Components
Resistor 2.2 KΩ
This resistor is also used to limit electric current. In this circuit, it is connected in series with the LDR to form a voltage divider and to help the transistor to detect changes in light levels accurately.
LDR
Principle of operation
Components
LED
This is a small light-emitting diode which glows light when an electric current flows through it. In this circuit, it works as an indicator: it lights up to show that the circuit is working and the relay is activated (when it is dark in this case).
LDR
Principle of operation
Components
Relay 5V
This in an electromagnetic switch which uses a small current to control a larger current. In this circuit, it isolates the low-voltage control from the high-voltage lamp. When the transistor activates it, the relay closes and lets 220V power flow to the lamp.
LDR
Principle of operation
Components
LDR
This is a sensor whose resistance changes with different light levels. In this circuit, it is the brain that detects darkness: as it gets dark, it signals the transistor to turn on the relay and lamp.
In conclusion
This project demonstrates how simple electronics can solve everyday problems, such as saving energy and improving comfort. It enhances skills in electronic design and opens the door to developing more complex systems, like smartphone-controlled lighting. Always remember safety with high voltage, and enjoy the experience of innovation.
Created by:
- Abdulhalim Mohammed
- Abdulrahman Ahmed
- Abdulrahman Mahmoud
- Ali Ahmed
- Mayer Maged
- Mennat Allah Ibrahim
- Mohammed Ayman
- Mohammed Raafat
- Nada Ahmed
- Nariman Mohammed
Supervised by:
- Dr/ Rawaa Mohammed