Monostable (one-shot) multivibrator — need for an external trigger Assess the statement: “A one-shot is a special type of multivibrator that must be triggered to produce each output pulse.”

Introduction / Context:
Multivibrators are categorized by stability: astable (no stable state), monostable (one stable state), and bistable (two stable states). A monostable, commonly called a one-shot, produces a single pulse of defined width in response to a trigger. Understanding this behavior is key to designing timers, pulse stretchers, and debounce circuits.

Given Data / Assumptions:

• The device has one stable state and returns to it automatically.
• An external triggering event initiates the temporary unstable state.
• Pulse width is set by internal or external timing elements (RC, digital counters, etc.).

Concept / Approach:
Upon receiving a valid trigger, the one-shot output changes state and stays there for a predetermined period T. After T elapses, the circuit self-resets to the stable state. There are retriggerable and non-retriggerable versions; both still require a trigger for the first pulse.

Step-by-Step Solution:
Hold the device in its stable state with no trigger.Apply a trigger edge/level; output asserts for interval T.After T, output returns to the stable level automatically.If retriggerable, a new trigger during T extends the pulse; if not, it is ignored.

Verification / Alternative check:
Timing diagrams and datasheets (e.g., 74HC123 retriggerable one-shot) show the dependence on triggers to produce pulses.

Why Other Options Are Wrong:
“Incorrect” contradicts the definition of monostable. Limitations like “only for non-retriggerable” or “only when RC timing is used” are unnecessary; trigger dependence is fundamental regardless of timing implementation.

Common Pitfalls:
Confusing monostable with astable oscillators; improper trigger conditioning leading to multiple pulses; not debouncing mechanical triggers.

Final Answer:
Correct