Introduction to Electronics - Filters: First-order filters in real life applications

Real-world applications of first- and second-order filters

Here are some everyday applications for these filters:

Audio applications:

When you adjust the bass or treble controls on a music player, simple first-order filters are shaping the sound. Capacitors and resistors modify the balance of low and high frequencies to match your preference.

Sensor inputs:

An Arduino reading a temperature sensor can receive noisy signals due to environmental interference. A small RC low-pass filter, using just a resistor and a capacitor, can significantly improve the quality of the sensor reading.

Motor control:

When controlling a motor’s speed with PWM (Pulse Width Modulation), a first-order low-pass filter can smooth the voltage and prevent the motor from producing audible whining noises.

Wireless systems:

Before transmitting or receiving wireless signals, circuits often include filters to ensure that only the desired frequencies are used. First-order filters can remove simple spurious signals, while second-order filters are sometimes used for tighter frequency control.

What about second-order filters?

While first-order filters are sufficient for many tasks, second-order filters are valuable when:

• A sharper transition between passed and blocked frequencies is required.
• Higher selectivity is needed, such as isolating a very narrow frequency band in communication systems.
• Improved stability and control over gain and phase are critical, such as in feedback control systems.

Learning second-order filters becomes natural and much easier once you are confident with the concepts and behaviours of first-order filters.

Ready for the next tutorial in this series? Here's the next one, or choose an alternative from the list of articles in the side bar. There's also lots of interesting article in our Blog. where you can read about off-grid communication technologies, electronics test equipment, course updates, and much more.