Deep Dive: E7A05
The correct answer is D: Astable multivibrator. Which of the following circuits continuously alternates between two states without an external clock signal is an astable multivibrator. Astable multivibrators oscillate continuously. For amateur radio operators, this is important for digital circuits. Understanding this helps when working with oscillators.
Why Other Answers Are Wrong
Option A (Monostable multivibrator): Incorrect. Monostable has one stable state, doesn't continuously alternate - astable does. Monostable isn't the answer. Option B (J-K flip-flop): Incorrect. J-K flip-flop needs clock signal - astable doesn't need external clock. J-K flip-flop isn't the answer. Option C (T flip-flop): Incorrect. T flip-flop needs clock signal - astable doesn't need external clock. T flip-flop isn't the answer.
Exam Tip
Circuit continuously alternating without external clock = astable multivibrator. Think 'A'stable = 'A'lternates 'A'utomatically (no external clock). Astable multivibrators oscillate continuously. Not monostable (one stable state), not J-K flip-flop (needs clock), not T flip-flop (needs clock) - just astable multivibrator.
Memory Aid
Circuit continuously alternating without external clock = astable multivibrator. Think 'A'stable = 'A'lternates automatically. Astable multivibrators oscillate continuously. Important for digital circuits.
Real-World Example
A circuit that continuously alternates between two states without an external clock signal: It's an astable multivibrator. Astable multivibrators are free-running oscillators that continuously switch states. This is the circuit - astable multivibrator.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E7A
Reference: 2024-2028 Question Pool · E7 - Practical Circuits
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E7A topic.