Timer IC 555 — Astable Mode How many stable states does an astable multivibrator have? Choose the correct count.

Introduction / Context:
An astable multivibrator built with a 555 or logic gates is a free running oscillator. It continually switches between two conditions without external triggers. The key idea is whether any of those conditions is stable in the absence of timing action.

Given Data / Assumptions:

• Astable configuration, not monostable or bistable.
• Standard 555 thresholds at 1/3 Vcc and 2/3 Vcc.
• Proper RC network connected to charge and discharge the timing capacitor.

Concept / Approach:
A stable state is one where the circuit remains indefinitely without an external disturbance. In an astable, the timing capacitor never rests at a final value; it charges and discharges between thresholds, driving the comparator outputs and flip flop to toggle continuously.

Step-by-Step Solution:
1) In astable mode, the capacitor charges toward Vcc through resistors and discharges toward ground through a resistor and the discharge transistor.2) Crossing 2/3 Vcc forces a state change that initiates discharge; crossing 1/3 Vcc forces another state change that initiates charge.3) Because thresholds are repeatedly crossed, neither state is stable; oscillation persists without triggers.

Verification / Alternative check:
Datasheets describe the astable as having no stable states and two quasi stable states that are left automatically by the RC dynamics.

Why Other Options Are Wrong:

• 1: A single stable state characterizes monostable, not astable.
• 2: Two stable states describe a bistable flip flop, not an astable.
• 3: Not applicable to standard multivibrator classifications.

Common Pitfalls:
Confusing quasi stable dwell times with true stability; mixing up astable with monostable or bistable terms.

Final Answer:
0