Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-001-009
A circuit depending on positive feedback for its operation would be a:
- A mixer
- B detector
- C audio amplifier
- D variable-frequency oscillator
Correct answer: D — variable-frequency oscillator. From the official ISED question bank, verified word for word.
Why
A variable-frequency oscillator needs positive feedback to keep generating a steady signal at a specific pitch, which can be adjusted to change that frequency. The full explanation — and one for every question — is in Pro.
Practise this section
Transmitters, modulation and processing: AM, FM, SSB, keying, speech processing, and the numbers behind occupied bandwidth.