In the context of a control system, feedback has a more technical meaning. It refers to taking a portion of the system’s output and feeding it back into the input to control the system’s behavior.
There are two main types:
Positive Feedback (Regenerative Feedback)
- Meaning: The feedback signal is added to the input.
- Effect: Increases the overall system output.
- Result: Can make the system unstable if not controlled.
Example:
- In amplifiers, positive feedback can increase gain.
- In oscillators, it helps generate continuous signals.
Output reinforces the input → grows stronger
Negative Feedback (Degenerative Feedback)
- Meaning: The feedback signal is subtracted from the input.
- Effect: Reduces the difference (error) between desired and actual output.
- Result: Makes the system more stable and accurate.
Example:
- Temperature control in an AC: if the room is too hot, cooling increases; if too cold, cooling decreases.
- Speed control in motors.
Output corrects the input → keeps things stable
Comparison:
| Type | Feedback Action | Effect on System |
|---|---|---|
| Positive Feedback | Adds to input | Increases output, less stable |
| Negative Feedback | Subtracts from input | Stabilizes, improves accuracy |
Summary:
- Negative feedback → control & stability (most commonly used)
- Positive feedback → amplification or oscillation