Voltage/Current Sources

Definition: Voltage and current sources are components in electrical circuits that provide electrical energy. They can be classified based on their characteristics and behavior.

1. Ideal Sources

  • Ideal Voltage Source:
    • Definition: A theoretical device that provides a constant voltage regardless of the current drawn from it.
    • Characteristics:
      • Infinite internal resistance.
      • Voltage remains constant (V = V₀) across all loads.
  • Ideal Current Source:
    • Definition: A theoretical device that provides a constant current regardless of the voltage across it.
    • Characteristics:
      • Zero internal resistance.
      • Current remains constant (I = I₀) regardless of the load.

2. Non-Ideal Sources

  • Non-Ideal Voltage Source:
    • Definition: A real-world voltage source that has some internal resistance.
    • Characteristics:
      • Voltage drops when current is drawn (V = V₀ - I × R_internal).
      • Cannot maintain constant voltage under varying load conditions.
  • Non-Ideal Current Source:
    • Definition: A real-world current source that has some internal resistance.
    • Characteristics:
      • Current may vary with changes in load voltage (I = I₀ - V/R_internal).
      • Cannot maintain constant current under varying load conditions.

3. Independent Sources

  • Definition: Sources that provide a constant voltage or current regardless of the circuit conditions.
  • Characteristics:
    • Do not depend on any other circuit variables.
    • Can be either ideal or non-ideal.
  • Examples: Batteries (voltage source), constant current sources.

4. Dependent Sources

  • Definition: Sources whose output (voltage or current) depends on another voltage or current in the circuit.
  • Characteristics:
    • Can be voltage-controlled or current-controlled.
    • Represented in circuit diagrams with a diamond shape.
  • Examples:
    • Voltage-Controlled Voltage Source (VCVS): Output voltage depends on an input voltage.
    • Current-Controlled Current Source (CCCS): Output current depends on an input current.

5. Source Transformation

  • Definition: A technique used to simplify circuit analysis by converting between equivalent voltage and current sources.
  • Process:
    • Voltage Source to Current Source:
      • A voltage source (V) in series with a resistor (R) can be transformed into a current source (I = V/R) in parallel with the same resistor.
    • Current Source to Voltage Source:
      • A current source (I) in parallel with a resistor (R) can be transformed into a voltage source (V = I × R) in series with the same resistor.
  • Benefits:
    • Simplifies circuit analysis and calculations.
    • Helps in understanding complex circuits by breaking them down into simpler components.