Basic Electronic Circuits and Components

Posted on Mar 25, 2025 in Textile Technology and Design Engineering

Basic Electronic Circuits

Components and Principles

  • Resistance, Potentiometer, Transistor: These are fundamental electronic components.
  • AC Cycle: It completes a cycle reaching 220V at 50 cycles per second (50 Hz).
  • Potentiometer Function:
    • Left (Counter-Clockwise): Lowest resistance, LED is brighter.
    • Right (Clockwise): Highest resistance, LED is dimmer.
  • Diode Behavior (L1, L2, and L4):
    • L1 and L2 light up because they are correctly polarized (positive to positive and negative to negative), allowing current to flow.
    • L4 does not light up because it is reverse-biased (polarity is reversed), blocking current flow.
  • Transistor Circuit: The circuit on the left controls the transistor, allowing the other part of the circuit to operate.
  • Applications:
    • Temperature Sensor (Fire Alarm)
    • Light Sensor (Light-Dependent Resistor controlling lamps)
  • Resistance Identification: Determining the value of a resistor.
  • Light Regulation: Adjusting the brightness of a light source.
  • Current in Series Circuit: Yes, the current would be the same in a series circuit.

LDR and Circuit Calculations

  1. LDR Function: When the Light-Dependent Resistor (LDR) receives full light, it has lower resistance, activating the transistor and enabling the other part of the circuit.
  2. Calculations:
    • V = I x R (Ohm’s Law)
    • Total Resistance (R) = R1 + R2 = 10Ω + 20Ω = 30Ω
    • Total Current (I) = V / R = 5V / 30Ω = 0.16A
    • Voltage across R1 (V1) = I x R1 = 0.16A x 10Ω = 1.6V
    • Voltage across R2 (V2) = I x R2 = 0.16A x 20Ω = 3.2V (Note: The original calculation had a slight error, it should be 3.2V, not 3.5V)
    • Answers: 0.16A, 1.6V, 3.2V
  3. Circuit Observation: Everything is correct.