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Low Pass RC Filter Equation:
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A low pass RC filter is an electronic circuit that allows signals with a frequency lower than the cutoff frequency to pass through while attenuating signals with frequencies higher than the cutoff frequency. It consists of a resistor (R) and capacitor (C) in series.
The calculator uses the low pass RC filter equation:
Where:
Explanation: The cutoff frequency is the point where the output signal is attenuated by 3 dB (about 70.7% of the input voltage).
Details: The cutoff frequency determines the filter's frequency response characteristics and is crucial for designing circuits that need to block high-frequency noise while passing desired low-frequency signals.
Tips: Enter resistance in ohms and capacitance in farads. For practical values, resistance is typically in ohms (Ω) and capacitance in microfarads (μF) or nanofarads (nF).
Q1: What happens at the cutoff frequency?
A: At the cutoff frequency, the output voltage is 70.7% of the input voltage (-3 dB point), and the phase shift is 45 degrees.
Q2: How does changing R or C affect the cutoff frequency?
A: Increasing either R or C lowers the cutoff frequency, while decreasing either raises it. They have an inverse relationship with fc.
Q3: What's the difference between low pass and high pass filters?
A: A low pass filter passes frequencies below the cutoff, while a high pass filter passes frequencies above the cutoff.
Q4: Can I cascade multiple RC filters?
A: Yes, but each additional stage increases the roll-off rate (-20 dB/decade per stage) while affecting the overall cutoff frequency.
Q5: What are typical applications of RC low pass filters?
A: Common uses include noise reduction, signal smoothing, anti-aliasing in ADCs, and preventing high-frequency interference in audio circuits.