Latest Filters Projects

An A-Weighted Analog Filter that Mimics the Response of the Human Ear

In this project, we design an A-weighted analog noise filter for audio frequencies. The filter provides a variable frequency gain response that is similar to that of our hearing.

October 29, 2023 by John Woodgate

Design of an Unweighted Audio Filter with Flat Frequency Response

This article presents the design of an unweighted (Z-weighted) audio filter with a flat frequency response from 20 Hz to 20 kHz for the measurement of audio noise.

July 23, 2023 by John Woodgate

An RMS Detector for a Wideband Voltmeter—Design and Operation

This project demonstrates the design and operation of a root-mean-squared (RMS) detector for inclusion in a wideband voltmeter. The RMS detector is useful for measuring certain signal types, including noise, since it provides an indication of the energy in a signal.

June 25, 2023 by John Woodgate

Designing a Wideband Analog Voltage and Current Meter

Design a wideband analog multimeter to measure AC voltages and currents from 20 Hz to 1 MHz with a selectable sensitivity from 1 mV to 100 V, while the ammeter has a selectable current sensitivity of 10 mA to 10 A.

May 03, 2023 by John Woodgate

Designing a Quadrature Network Using an All-pass Filter

Quadrature networks convert a single input signal into two outputs with a 90-degree phase difference. This article explains how to design quadrature networks using all-pass filters.

December 23, 2022 by John Woodgate

Magnetic Field Strength Meter and Calibrator

This project will explain how to develop a system to measure magnetic field emissions at frequencies up to 150 kHz from high-current power cables without cutting or disturbing the cable.

October 28, 2022 by John Woodgate

How to Build a Class-D Power Amp

Learn how to build your own Class D power amplifier—one of the most efficient ways to listen to music.

August 29, 2018 by Cezar Chirila

Incorporating Microphone Functionality into a Robot System

In this article, we’ll look at a fairly straightforward circuit that enables a robot or other device to detect sound.

September 11, 2017 by Robert Keim

Build Your Own LED Photography Ring Light

LED ring flashes and lights can be a valuable tool for photographers. In this tutorial, we are going to build our own ring light out of LEDs!

January 26, 2017 by Alex Udanis

Digital-to-Analog Conversion with the SAM4S Peripheral DMA Controller

Part Three in this three-article series shows you how to generate values for a discrete sinusoid and continuously convert this data into an analog signal without overburdening the CPU.

May 09, 2016 by Robert Keim

Understanding and Using the SAM4S Digital-to-Analog Converter

Part Two in this three-article series explores the SAM4S DAC. We’ll look at hardware configuration, electrical characteristics, and the application programming interface.

May 04, 2016 by Robert Keim

DMA Digital-to-Analog Conversion with a SAM4S Microcontroller: The Timer/Counter

Part One in this three-article series focuses on using the SAM4S timer/counter peripheral to precisely control the DAC’s sampling rate.

April 28, 2016 by Robert Keim

PWM Digital-to-Analog Conversion with the SAM4S Xplained Pro

In this article we’ll use the SAM4S Xplained Pro development platform to get some hands-on experience with a PWM DAC.

April 19, 2016 by Robert Keim

Building Raspberry Pi Controllers Part 5: Reading Analog Data with an RPi

Learn how to read electrical signals and data from an analog device using the Step Response technique in Part 5 of the Building Raspberry Pi Controllers series.

February 09, 2016 by Don Wilcher

Make an Analog Sound Reactive LED Strip

This analog design allows your LEDs to respond to your music. Just plug your music source into this which sends a channel to your sound system and some LEDs.

October 28, 2015 by Fadi Kasem

Build a Laser Communication System

Use a laser and a photo resistor to build a laser based point-to-point communication system. The best part? It's under $10.

October 22, 2015 by Jacob Smith

EFM8 Sound Synthesizer: Driving the Speaker

Part 2 in the “How to Make an EFM8-Based Sound Synthesizer” series.

September 11, 2015 by Robert Keim

Ambient Light Monitor: Measuring and Interpreting Ambient Light Levels

Part 3 in the “How to Make an Ambient Light Monitor” series. The project continues by building an ambient light sensor circuit on a breadboard, digitizing the circuit’s output signals, and interpreting the digitized measurements.

August 05, 2015 by Robert Keim