The Cutoff Frequency Calculator helps determine the frequency at which a circuit begins to attenuate a signal, marking the transition between the passband and stopband in electronic filters. This is crucial for audio processing, communication systems, and circuit design.
Cutoff frequency is widely used in:
- Low-pass filters (allowing low frequencies while blocking higher ones).
- High-pass filters (allowing high frequencies while blocking lower ones).
- Band-pass and band-stop filters (allowing or rejecting a specific frequency range).
This calculator is particularly useful for engineers, students, and hobbyists working with resistor-capacitor (RC) and resistor-inductor (RL) circuits.
Formula of Cutoff Frequency Calculator
For an RC (Resistor-Capacitor) Circuit:
The cutoff frequency is calculated using:
f_c = 1 / (2π × R × C)
Where:
- f_c = Cutoff frequency (in hertz, Hz)
- R = Resistance (in ohms, Ω)
- C = Capacitance (in farads, F)
- π = Approximately 3.1416
For an RL (Resistor-Inductor) Circuit:
The cutoff frequency is calculated using:
f_c = R / (2π × L)
Where:
- f_c = Cutoff frequency (in hertz, Hz)
- R = Resistance (in ohms, Ω)
- L = Inductance (in henries, H)
- π = Approximately 3.1416
These formulas help determine the frequency response of electronic circuits, ensuring optimal design and performance.
General Cutoff Frequency Reference Table
The following table provides pre-calculated cutoff frequencies for different resistor and capacitor values.
| Resistance (Ω) | Capacitance (µF) | Cutoff Frequency (Hz) |
|---|---|---|
| 1,000 | 1 | 159.2 |
| 5,000 | 0.5 | 63.7 |
| 10,000 | 0.1 | 159.2 |
| 50,000 | 0.01 | 318.3 |
| 100,000 | 0.005 | 318.3 |
This table provides a quick reference for engineers and students designing electronic filters.
Example of Cutoff Frequency Calculator
A low-pass filter circuit has:
- Resistance (R) = 10,000Ω
- Capacitance (C) = 0.1µF (0.0000001F)
Using the formula:
f_c = 1 / (2 × 3.1416 × 10,000 × 0.0000001)
f_c = 159.2 Hz
This means the circuit attenuates frequencies above 159.2 Hz, allowing only lower frequencies to pass.
Most Common FAQs
Cutoff frequency defines where a circuit starts blocking signals, ensuring proper filtering, noise reduction, and signal processing.
To lower the cutoff frequency, increase capacitance or resistance in an RC circuit, or increase inductance in an RL circuit.
Yes, the same formulas apply, but in a high-pass filter, frequencies above the cutoff frequency pass through, while lower frequencies are blocked.