KIT INCLUDED:

• Breadboard 400 point – 1
• 9V Battery - 1
• Snapper – 1
• Resistor 1k – 2
• Resistor 100 k – 2
• Transistor BC547 – 2
• Led – 8
• Single Stand Wire 2m – 1

HARDWARE REQUIRED

• Breadboard 400 point – 1
• 9V Battery - 1
• Snapper – 1
• Resistor 1k – 2
• Resistor 100 k – 2
• Transistor BC547 – 2
• Led – 8
• Single Stand Wire 2m – 1

PIN DESCRIPTION

LDR

LED

BC547 Transistor

CIRCUIT DESCRIPTION

• Connect LDR one pin to the negative rail on the breadboard.
• Connect LDR pin 2 to the base of the transistor and the same rail is connected with the positive rail via a 100k resistor.
• Connect LED negative with the collector of the transistor and negative to positive rail via 1 k resistor
• Connect the emitter of the transistor to the negative rail
• Now connect the battery.

WORKING

Welcome to the LED controller project by making a dark sensor using LDR (Photodiode). The basic principle depends upon the LDR which is being described here. Automatic Dark Detector senses darkness and as light decreases and LDR meets maximum threshold resistance, the circuit automatically switches on the LED.

Dark Sensor can also be used with the variable resistor. In such cases, the sensitivity of the circuit can be adjusted with a variable resistor.

• • High Resistance -> more darkness to switch on the LED.
  • Low Resistance -> less darkness top switch on the LED.

Now, whenever you put a finger or hand over the LDR (Light dependent resistor), that time LED will glow.