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Battery-Powered Light-Activated Alarm with BC547 Transistor and Photocell

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Circuit Documentation

Summary

This document provides a detailed overview of a simple electronic circuit that includes a 9V battery, a BC547 transistor, a photocell (LDR), a resistor, a buzzer, and a red LED. The circuit is designed to activate the buzzer and LED based on the light intensity detected by the photocell.

Component List

  1. 9V Battery

    • Description: Provides the power supply for the circuit.
    • Pins: +, -
  2. BC547 Transistor

    • Description: A general-purpose NPN transistor used for switching and amplification.
    • Pins: Collector, Base, Emitter
  3. Photocell (LDR)

    • Description: A light-dependent resistor that changes its resistance based on the light intensity.
    • Pins: pin 0, pin 1
  4. Resistor

    • Description: Limits the current flow in the circuit.
    • Pins: pin1, pin2
    • Properties:
      • Resistance: 10,000 Ohms
  5. Buzzer

    • Description: Produces sound when activated.
    • Pins: PIN, GND
  6. LED: Two Pin (red)

    • Description: Emits red light when current flows through it.
    • Pins: cathode, anode

Wiring Details

9V Battery

  • + Pin:

    • Connected to the Collector of the BC547 Transistor
    • Connected to pin 0 of the Photocell (LDR)
    • Connected to the PIN of the Buzzer
    • Connected to pin1 of the Resistor
    • Connected to the cathode of the LED
  • - Pin:

    • Connected to the Emitter of the BC547 Transistor
    • Connected to pin 1 of the Photocell (LDR)
    • Connected to the GND of the Buzzer
    • Connected to pin2 of the Resistor
    • Connected to the anode of the LED

BC547 Transistor

  • Collector:

    • Connected to the + pin of the 9V Battery
    • Connected to pin 0 of the Photocell (LDR)
    • Connected to the PIN of the Buzzer
    • Connected to pin1 of the Resistor
    • Connected to the cathode of the LED
  • Emitter:

    • Connected to the - pin of the 9V Battery
    • Connected to pin 1 of the Photocell (LDR)
    • Connected to the GND of the Buzzer
    • Connected to pin2 of the Resistor
    • Connected to the anode of the LED

Photocell (LDR)

  • pin 0:

    • Connected to the + pin of the 9V Battery
    • Connected to the Collector of the BC547 Transistor
    • Connected to the PIN of the Buzzer
    • Connected to pin1 of the Resistor
    • Connected to the cathode of the LED
  • pin 1:

    • Connected to the - pin of the 9V Battery
    • Connected to the Emitter of the BC547 Transistor
    • Connected to the GND of the Buzzer
    • Connected to pin2 of the Resistor
    • Connected to the anode of the LED

Resistor

  • pin1:

    • Connected to the + pin of the 9V Battery
    • Connected to the Collector of the BC547 Transistor
    • Connected to pin 0 of the Photocell (LDR)
    • Connected to the PIN of the Buzzer
    • Connected to the cathode of the LED
  • pin2:

    • Connected to the - pin of the 9V Battery
    • Connected to the Emitter of the BC547 Transistor
    • Connected to pin 1 of the Photocell (LDR)
    • Connected to the GND of the Buzzer
    • Connected to the anode of the LED

Buzzer

  • PIN:

    • Connected to the + pin of the 9V Battery
    • Connected to the Collector of the BC547 Transistor
    • Connected to pin 0 of the Photocell (LDR)
    • Connected to pin1 of the Resistor
    • Connected to the cathode of the LED
  • GND:

    • Connected to the - pin of the 9V Battery
    • Connected to the Emitter of the BC547 Transistor
    • Connected to pin 1 of the Photocell (LDR)
    • Connected to pin2 of the Resistor
    • Connected to the anode of the LED

LED: Two Pin (red)

  • cathode:

    • Connected to the + pin of the 9V Battery
    • Connected to the Collector of the BC547 Transistor
    • Connected to pin 0 of the Photocell (LDR)
    • Connected to the PIN of the Buzzer
    • Connected to pin1 of the Resistor
  • anode:

    • Connected to the - pin of the 9V Battery
    • Connected to the Emitter of the BC547 Transistor
    • Connected to pin 1 of the Photocell (LDR)
    • Connected to the GND of the Buzzer
    • Connected to pin2 of the Resistor

Code

There is no microcontroller code associated with this circuit.