FCC Exam Question: 6A307

Bleeder resistors are used in power supplies:

A. To improve the output voltage regulation
B. They also discharge the filter capacitor when the power is turned off
C. Either A or B
D. None of the above
Correct Answer: C

Explanation: Bleeder resistors serve a dual purpose in power supplies. Firstly, they improve output voltage regulation (Option A). By drawing a small, constant current from the power supply output, bleeder resistors ensure there's always a minimum load. This prevents the output voltage from rising excessively when the primary load is very light or disconnected, leading to more stable operation. Secondly, and critically for safety, bleeder resistors discharge the filter capacitors when the power supply is turned off (Option B). Filter capacitors can store dangerous levels of electrical charge for extended periods after the main power is removed. The bleeder resistor provides a continuous path for this stored energy to dissipate, making the circuit safe to handle after a reasonable waiting period. Since bleeder resistors perform both functions, option C, "Either A or B," is the most comprehensive and correct answer.

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