Astable multivibrator fundamentals Which of the following does an astable multivibrator inherently require in order to operate?

Introduction / Context:
An astable multivibrator is a free-running oscillator that continuously switches states without any external triggering. It produces a periodic waveform determined by its timing network. This distinguishes it from monostable (one-shot) and bistable (latch) circuits that require specific triggers or stable inputs.

Given Data / Assumptions:

• We want the defining requirement of an astable topology.
• Internal RC timing or regenerative feedback sustains oscillation.
• No external periodic input is necessary once powered.

Concept / Approach:
The hallmark of an astable is self-oscillation. Component values set frequency and duty cycle, but external drive is not required, only power. Many implementations exist (transistor pair, op-amp, Schmitt trigger inverter chains, or 555), but all share autonomous operation.

Step-by-Step Solution:

Verification / Alternative check:
Examine a 555 astable or a cross-coupled transistor astable: after power-up, oscillation begins without any external trigger waveform.

Why Other Options Are Wrong:

• Balanced time constants: not strictly required; frequency and duty cycle can be asymmetric.
• Matched transistors: helpful in symmetric designs but not mandatory.
• Dual J-K flip-flops: one of many possible implementations, not a requirement.

Common Pitfalls:
Assuming symmetry is required for oscillation; it is not. Only sufficient loop gain and timing network are needed.

Final Answer:
no input signal