Astable multivibrator behavior Which statement best describes an astable multivibrator circuit?

Introduction / Context:
Multivibrators are foundational timing and waveform-generation circuits. Understanding the differences among monostable (one-shot), bistable (flip-flop), and astable (free-running) forms is crucial in digital design and signal generation. The astable multivibrator is the go-to choice when a continuous clock or square wave is needed without external triggers.

Given Data / Assumptions:

• No external trigger required once power is applied.
• Feedback network ensures periodic switching between states.
• Waveform is typically a rectangular/square wave whose period is set by R and C components.

Concept / Approach:

An astable multivibrator has no stable state; it continually oscillates between two quasi-stable states. This continuous toggling yields a repetitive output signal whose frequency and duty cycle are determined by component values. Implementations include transistor cross-coupled designs and IC solutions such as the 555 in astable mode or CMOS inverters with RC feedback.

Step-by-Step Explanation:

Verification / Alternative check:

Measuring the output with an oscilloscope shows a periodic waveform without any external trigger event. Changing R or C shifts the period and, depending on topology, the duty cycle.

Why Other Options Are Wrong:

• “Two stable states” describes a bistable (flip-flop), not an astable.
• “Free-running” alone is incomplete; it must also produce a continuous output.
• “Requires a trigger” describes a monostable one-shot, not an astable.

Common Pitfalls:

• Confusing “astable” with “unstable”; astable is intentionally designed to oscillate.
• Assuming duty cycle is always 50%; many astables have asymmetric charge/discharge paths.

Final Answer:

is free-running and produces a continuous output signal