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Battery-Powered Light-Activated LED Circuit with BC547 Transistor

Image of Battery-Powered Light-Activated LED Circuit with BC547 Transistor

Circuit Documentation

Summary

This circuit is designed to control an LED using a BC547 transistor, a photocell (LDR), a resistor, and a 9V battery. The LED will light up based on the light intensity detected by the photocell. The BC547 transistor acts as a switch, controlled by the photocell and resistor network.

Component List

  1. BC547 Transistor

    • Pins: Collector, Base, Emitter
    • Description: NPN Bipolar Junction Transistor
    • Purpose in Circuit: Acts as a switch to control the LED based on the input from the photocell.
  2. Photocell (LDR)

    • Pins: pin 0, pin 1
    • Description: Light Dependent Resistor
    • Purpose in Circuit: Senses the ambient light level and provides a variable resistance based on the light intensity.
  3. Resistor

    • Pins: pin1, pin2
    • Description: Fixed Resistor
    • Properties: 100 Ohms
    • Purpose in Circuit: Limits the current flowing through the circuit to protect the components.
  4. 9V Battery

    • Pins: -, +
    • Description: Power Source
    • Purpose in Circuit: Provides the necessary voltage to power the circuit.
  5. LED: Two Pin (red)

    • Pins: cathode, anode
    • Description: Light Emitting Diode
    • Purpose in Circuit: Emits light when current flows through it.

Wiring Details

BC547 Transistor

  • Collector: Connected to the cathode of the LED.
  • Base: Connected to pin 1 of the Photocell and pin 2 of the Resistor.
  • Emitter: Connected to pin 0 of the Photocell and the negative terminal of the 9V Battery.

Photocell (LDR)

  • pin 0: Connected to the Emitter of the BC547 Transistor and the negative terminal of the 9V Battery.
  • pin 1: Connected to the Base of the BC547 Transistor and pin 2 of the Resistor.

Resistor

  • pin1: Connected to the anode of the LED and the positive terminal of the 9V Battery.
  • pin2: Connected to the Base of the BC547 Transistor and pin 1 of the Photocell.

9V Battery

  • - (Negative): Connected to pin 0 of the Photocell and the Emitter of the BC547 Transistor.
  • + (Positive): Connected to the anode of the LED and pin 1 of the Resistor.

LED: Two Pin (red)

  • cathode: Connected to the Collector of the BC547 Transistor.
  • anode: Connected to the positive terminal of the 9V Battery and pin 1 of the Resistor.

Code

No microcontroller code is provided for this circuit.