Which of the following circuits continuously alternates between two states without an external clock signal?
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.
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 Application
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.
Key Concepts
Why Other Options 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.
题目解析
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.
考试技巧
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.
记忆口诀
Circuit continuously alternating without external clock = astable multivibrator. Think 'A'stable = 'A'lternates automatically. Astable multivibrators oscillate continuously. Important for digital circuits.
实际应用示例
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.
错误选项分析
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.
知识点
Circuits, Continuously alternates, Two states, Without external clock signal, Astable multivibrator
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.