Street light

1. Automatic Street Light ON/OFF
System
(Without Arduino)
• A smart lighting system using LDR, transistor,
and relay without microcontroller.

2. Introduction
• • Street lights often remain ON during
daytime due to manual errors.
• • Automatic system reduces energy wastage.
• • Works on light intensity using LDR.

3. Objective
• • Turn ON lights automatically at night.
• • Turn OFF lights automatically in daytime.
• • Reduce electricity consumption.
• • Low-cost automation.

4. Working Principle
• • LDR resistance decreases in light, increases
in dark.
• • Controls base current of transistor.
• • Relay switches street light ON/OFF based on
transistor output.

5. Components Required
• • LDR (Light Dependent Resistor)
• • Transistor (BC547/BC548)
• • Relay 12V SPDT
• • Resistors: 10kΩ, 1kΩ
• • Diode 1N4007
• • AC Lamp
• • 12V DC Supply

6. Circuit Diagram (Text Format)
• +12V DC → Relay → Transistor → Ground
• LDR + 10kΩ → Base resistor → Transistor
• Relay NO → AC Lamp → Neutral
• 1N4007 diode across relay

7. Advantages
• • Low cost and simple design.
• • No microcontroller required.
• • Automatic operation.
• • Low maintenance.

8. Applications
• • Street lighting
• • Garden/pathway lighting
• • Parking lots
• • Industrial lighting
• • Solar street lights

9. Conclusion
• This system provides an economical, efficient,
and reliable solution for automatic outdoor
lighting without using any microcontroller.