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RC Low Pass Filter Formula:
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The RC low pass filter is an electronic circuit that allows signals with a frequency lower than a certain 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 RC low pass filter formula:
Where:
Explanation: The cutoff frequency is the point at which the output signal power is reduced to half (-3dB) of the input signal power.
Details: Accurate cutoff frequency calculation is crucial for designing filters in audio systems, signal processing, radio communications, and many other electronic applications where frequency separation is required.
Tips: Enter resistance in ohms (Ω) and capacitance in farads (F). All values must be valid (resistance > 0, capacitance > 0). For microfarads (μF), remember that 1μF = 0.000001F.
Q1: What is the -3dB point?
A: The -3dB point is the frequency at which the output voltage drops to approximately 70.7% of the input voltage, representing half the power.
Q2: Can I use different units for R and C?
A: Yes, but you must ensure consistent units. Common combinations are Ω and F for Hz, kΩ and μF for Hz, or MΩ and μF for Hz.
Q3: What happens above the cutoff frequency?
A: Signals above the cutoff frequency are attenuated at a rate of -20dB per decade (or -6dB per octave).
Q4: Are there limitations to this simple RC filter?
A: Yes, RC filters have a relatively gentle roll-off and may not provide sufficient attenuation for applications requiring sharp frequency cutoff.
Q5: How can I create a steeper roll-off?
A: You can cascade multiple RC filters or use active filters with operational amplifiers to achieve steeper roll-off characteristics.