Estimated reading time: 3 minutes
What is an RC High Pass Filter?
An RC high pass filter is a circuit. It has a resistor and a capacitor. This circuit lets high frequencies pass. It stops low frequencies. We use it to get rid of unwanted low-frequency parts in a signal. This filter is simple. It is common in many electronics. We use it for audio, sensors, and other things. It is a good first circuit to learn about.
Get Started
Cutoff frequency (fc): – Hz
Gain at test freq: –
Phase at test freq: –°
Capacitor reactance |Xc|: – Ω
Magnitude (dB)
Phase (degrees)
Every high-pass filter has a cutoff frequency, the point which the filter starts to work. Frequencies above this point pass through the circuit easily, while those below it are attenuated. At the cutoff frequency, the output signal voltage is about 70.7 % of the input voltage, a standard measure. You can change the cutoff frequency by adjusting the resistor or capacitor value, and our calculator helps you find the right value quickly.
How to Calculate Cutoff Frequency
The math is simple. The formula for the cutoff frequency is:
fc = 1 / (2 π R C)
Here is what each part means:
- fc is the cutoff frequency in Hertz (Hz).
- π is approximately 3.14.
- R is the resistance in Ohms (Ω).
- C is the capacitance in Farads (F).
Use the correct units for R and C. The calculator handles unit conversion for you, turning kΩ, MΩ, mF, μF, nF, and pF into their base values so you avoid mistakes. Just enter your numbers and receive the correct result in seconds.
FAQ
A high-pass filter does exactly that: it removes low-frequency sounds such as deep bass or hum while allowing higher frequencies—like voices or cymbals—to pass through unaltered. This keeps woofers from trying to reproduce notes they can’t handle and ensures tweeters receive only the frequencies they were designed to play, resulting in clearer, more accurate sound from the speaker system.
No, they are not the same. An equalizer is a device that adjusts the volume of many different frequencies by employing multiple filters inside. A high-pass filter, on the other hand, is only one type of those filters—a small part of what an equalizer does. The equalizer itself is more complex and provides much greater control over sound.
Adding another circuit can change how the filter works. This is called "loading." The new circuit adds resistance. This changes the total resistance of the filter. It can move the cutoff frequency. To prevent this, the new circuit's resistance should be much higher. This makes sure the filter works as you planned. It is a very important step in circuit building.
Resistors and capacitors are readily available. They're available in many stores. You can find them online at Jinxinyang (https://www.szjxy-ic.com/). They're common and inexpensive, making them a great starting point for electronics beginners.
