Dependent and Independent Sources in Electrical Circuits

Independent Sources

• An independent source is a circuit element that provides a fixed voltage or current, regardless of any other voltages or currents elsewhere in the circuit.
• These sources are not influenced by circuit conditions; their output remains constant as specified.
• Examples include batteries (independent voltage source) and ideal current sources used in laboratory settings

Dependent (Controlled) Sources

• A dependent source, also known as a controlled source, is a circuit element whose output (voltage or current) depends on another voltage or current elsewhere in the circuit.
• The value provided by a dependent source changes in response to the controlling variable, making them essential for modeling amplifiers and feedback systems.
• Dependent sources are categorized based on what controls them and what they output:
  • Voltage-Controlled Voltage Source (VCVS)
  • Current-Controlled Voltage Source (CCVS)
  • Voltage-Controlled Current Source (VCCS)
  • Current-Controlled Current Source (CCCS)

Comparison Table

Feature| Independent Source| Dependent Source
---|---|---
Output| Fixed, unaffected by circuit conditions| Controlled by another voltage or current
Types| Voltage, Current| VCVS, CCVS, VCCS, CCCS
Symbol| Circle| Diamond
Application| Batteries, generators, power supplies| Amplifiers, oscillators, sensor circuits
Circuit Terminals| Two| Four

Key Points

• Independent sources are simple and predictable, making circuit analysis straightforward.
• Dependent sources introduce dynamic behavior, crucial for advanced electronic designs like amplifiers and control systems

• In circuit diagrams, independent sources are usually depicted with a circle, while dependent sources use a diamond shape

In summary, independent sources provide a constant output regardless of circuit conditions, while dependent sources adjust their output in response to other circuit variables