FCC Exam Question: 39E1

Which of the following best describes a standard full wave rectifier power supply?

A. It uses a capacitor input filter to provide good voltage regulation.
B. It must only use a single diode rectifier.
C. The ripple frequency is twice the input frequency.
D. It must always use a center tapped transformer secondary.
Correct Answer: C

Explanation: A standard full-wave rectifier converts both the positive and negative halves of an AC input signal into pulsating DC. For every complete cycle of the input AC waveform (e.g., 60 Hz), a full-wave rectifier produces two output pulses. This effectively doubles the fundamental frequency of the remaining AC component (the ripple) in the output. Therefore, if the input frequency is 60 Hz, the ripple frequency will be 120 Hz, which is twice the input frequency. Option A is incorrect because while many power supplies use capacitor input filters to reduce ripple, the filter itself doesn't inherently provide "good voltage regulation"; that's typically achieved with a dedicated voltage regulator circuit after the filter. Option B is incorrect because a single diode forms a half-wave rectifier, not a full-wave rectifier. Full-wave rectifiers require at least two diodes (for a center-tapped design) or four diodes (for a bridge rectifier). Option D is incorrect because a full-wave bridge rectifier is a common standard design that does not require a center-tapped transformer secondary. It uses four diodes to achieve full-wave rectification from a standard transformer winding.

Pass Your FCC Exam!

Study offline, track your progress, and simulate real exams with the GMDSS Trainer app.


Includes Elements 1, 3, 6, 7R, 8, and 9.