This is a low-pass filter implemented using a resistor and an inductor. The inductor passes lower frequencies, causing the output voltage to fluctuate more. Higher frequencies are blocked, and there is reduced current across the resistor, keeping the output voltage closer to ground.
Below the circuit is the frequency response in dB for a range of frequencies. You can click on the frequency response graph to see the circuit in operation at that particular frequency.
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Previous: High-Pass Filter (RL)
Analog Filter Applet