Definition scope: “A multivibrator is a circuit that toggles between two digital levels, either free-running (continuous) or on demand (triggered).” Assess this statement.

Introduction / Context:
Multivibrators are foundational timing circuits in digital and mixed-signal electronics. They appear in three canonical forms—bistable, monostable, and astable—and underpin clocks, pulse stretchers, debouncers, and many other functions. This item checks a clear conceptual definition spanning these modes.

Given Data / Assumptions:

• Bistable: two stable states (e.g., flip-flop).
• Monostable: one stable state; produces a pulse when triggered (one-shot).
• Astable: no stable states; oscillates continuously (free-running).

Concept / Approach:
The essence of a multivibrator is the controlled switching between logic levels. In the astable case, this occurs autonomously, generating a square or rectangular waveform. In the monostable case, a trigger causes a temporary excursion (a pulse) before returning to the stable state. The bistable case toggles states on demand and stays until another trigger. The statement’s wording correctly captures “continuous, free-running” (astable) and “on demand” (monostable/bistable) behavior.

Step-by-Step Solution:

Verification / Alternative check:
Textbook definitions group monostable/astable/bistable under “multivibrator” families, each with characteristic waveforms and timing components (RC networks, Schmitt triggers, 555 timers, or logic feedback networks).

Why Other Options Are Wrong:

• Incorrect: Conflicts with standard categorization.
• Only true for astable / monostable: The term covers all three classic types, not one exclusively.

Common Pitfalls:
Thinking “multivibrator” means only oscillators (astable), ignoring monostable/bistable forms; confusing “on demand” (triggered) with level-sensitive gating.

Final Answer:
Correct