Question
Which of the following might be useful in reducing RF interference to audio frequency circuits?
Answer Options
- A) Bypass inductor
- B) Bypass capacitor
- C) Forward-biased diode
- D) Reverse-biased diode
Correct Answer: B
Explanation
RF Interference (RFI) often infiltrates audio circuits by coupling into the wiring and being rectified (turned into DC or audio frequency) by semiconductors. To prevent RFI from causing problems, the RF signal must be shunted to ground before it reaches the sensitive audio circuitry.
A bypass capacitor is ideal for this purpose. When installed on the signal line, the capacitor presents a very low impedance path to the high-frequency RF energy, effectively shorting the unwanted RF to ground, while maintaining a high impedance to the desired low-frequency audio signal. This action ‘bypasses’ the RF around the sensitive circuit, leaving only the audio intact.
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