Some Highlights from the contents Surround-sound decoder Compact amp Sampling rate converter Battery powered preamplifier Titan 2000 amplifier Crescendo Millennium amplifier Audio-DAC/ADC IR-S/PDFI receiver and transmitter High-End Power Amp Hi-fi Wireless Headset Paraphase Tone Control and more… Using Adobe Reader you are able to browse and search the articles on your computer, as well as print texts, circuit diagrams and PCB layouts.
Easy and Affordable Digital Signal Processing
The aim of this book is to teach the basic principles of Digital Signal Processing (DSP) and to introduce it from a practical point of view using the bare minimum of mathematics. Only the basic level of discrete-time systems theory is given, sufficient to implement DSP applications in real time. The practical implementations are described in real time using the highly popular ESP32 DevKitC microcontroller development board. With the low cost and extremely popular ESP32 microcontroller, you should be able to design elementary DSP projects with sampling frequencies within the audio range. All programming is done using the popular Arduino IDE in conjunction with the C language compiler.
After laying a solid foundation of DSP theory and pertinent discussions on the main DSP software tools on the market, the book presents the following audio-based sound and DSP projects:
Using an I²S-based digital microphone to capture audio sound
Using an I²S-based class-D audio amplifier and speaker
Playing MP3 music stored on an SD card through an I²S-based amplifier and speaker
Playing MP3 music files stored in ESP32 flash memory through an I²S-based amplifier and speaker
Mono and stereo Internet radio with I²S-based amplifiers and speakers
Text-to-speech output with an I²S-based amplifier and speaker
Using the volume control in I²S-based amplifier and speaker systems
A speaking event counter with an I²S-based amplifier and speaker
An adjustable sinewave generator with I²S-based amplifier and speaker
Using the Pmod I²S2 24-bit fast ADC/DAC module
Digital low-pass and band-pass real-time FIR filter design with external and internal A/D and D/A conversion
Digital low-pass and band-pass real-time IIR filter design with external and internal A/D and D/A conversion
Fast Fourier Transforms (FFT)
Jan Didden created Linear Audio in 2010 and published 14 Volumes between 2010 and 2017. Each 200-page Volume contains on average 10 articles by expert authors in the field of audio, acoustics, and instrumentation. Whether you are interested in tube amplifiers, solid-state equipment, loudspeaker design, capacitor and resistor distortion or distortion measurement, you are certain to find helpful advice and interesting discussions. From beginner to advanced level, for the audio professional or the serious hobbyist, this ExpertCollection will advance your understanding and offer new perspectives on common issues.
Bonus material included with this collection is a 5-part YouTube series on negative feedback as applied to audio by renowned author Jan Didden, and nine additional landmark audio articles and presentations.
If you are seriously interested in audio, acoustics, and instrumentation, you can’t afford to miss this! The published material is indexed and fully searchable and will provide an almost limitless resource for many years to come.
You can read about Linear Audio’s authors, and the Table of Contents of each Volume, at linearaudio.net.
The QA403 is QuantAsylum's fourth-generation audio analyzer. The QA403 extends the functionality of the QA402 with improved noise and distortion performance, in addition to a flatter response at band edges. The compact size of the QA403 means you can take it just about anywhere.
Features
24-bit ADC/DAC
Up to 192 kS/s
Fully isolated from PC
Differential Input/Output
USB powered
Built-in Attenuator
Fast Bootup and Driverless
The QA403 is a driverless USB device, meaning it’s ready as soon as you plug it in. The software is free and it is quick and easy to move the hardware from one machine to the next. So, if you need to head to the factory to troubleshoot a problem or take the QA403 home for a work-from-home day, you can do it without hassle.
No-Cal Design
The QA403 comes with a factory calibration in its flash memory, ensuring consistent unit-to-unit performance. On your manufacturing line you can install another QA403 and be confident what you read on one unit will be very similar to the next unit. It is not expected that re-calibration will be required at regular intervals.
Measurements
Making basic measurements is quick and easy. In a few clicks you will understand the frequency response, THD(+N), gain, SNR and more of your device-under test.
Dynamic Range
The QA403 offers 8 gain ranges on the input (0 to +42 dBV in 6 steps), and 4 gain ranges on the output (-12 to +18 dBV in 10 dB steps). This ensures consistent performance over very wide ranges of input and output levels. The maximum AC input to the QA403 is +32 dBV = 40 Vrms. The maximum DC is ±40 V, and the maximum ACPEAK + DC = ±56 V.
Easy Programmability
The QA403 supports a REST interface, making it easy to automate measurements in just about any language you might anticipate. From Python to C++ to Visual Basic—if you know how to load a web page in your favorite language, you can control the QA403 remotely. Measurements are fast and responsive, usually with dozens of commands being processed per second.
Isolated and USB Powered
The QA403 is isolated from the PC, meaning you are measuring your DUT and not chasing some phantom ground loop. The QA403 is USB powered, like nearly all our instruments. If you are setting up remotely, throw a powered hub in your bag and your entire test setup can be running with a minimum of cables.
Goodbye Soundcard, Hello QA403
Tired of trying to make a soundcard work? The calibration nightmare? The lack of gain stages? The limited drive? Are you tired of dealing with the fixed input ranges? The worry that you might destroy it with too much DC or AC? Tired of the ground loops? That’s why QuantAsylum built the QA403.
Specifications
Dimensions
177 x 44 x 97 mm (W x H x D)
Weight
435 g
Case Material
Powder-coating Aluminum (2 mm thick front panel, 1.6 mm thick top/bottom)
Downloads
Datasheet
Manual
GitHub
The intention of this book is to offer the reader understandings, ideas and solutions from the perspective of a workbench technician and electronics hobbyist. It is a descriptive text with many tables of useful data, servicing tips and supplementary notes of not so common knowledge.
Today there is a re-emerging, nostalgic interest in vinyl records and associated music entertainment gear. With this interest, there is a paralleled market for the repair of this gear.
This ‘hands-on’ servicing guide opens with fundamental considerations of the work space of repair and servicing. This includes a comprehensive discussion of essential test equipment and tools. Two chapters are devoted to obtaining servicing information about repair and obtaining spare parts. A key chapter is on general diagnosis and testing and includes the discussion of resistance, capacitance and inductance. These electrical properties are regularly in the mind of the repairer, so understanding of them is a key objective of this book. The next chapter is about time saving repair techniques and ensuring quality repair. The remaining chapters discuss entertainment equipment itself. Each of the chapters begins with an orderly discussion of the theory of operation and common and not so common problems specific to the equipment. All chapters conclude with a summary.
The State of Hollow State Audio in the Second Decade of the 21st Century
Vacuum-tube (or valve, depending upon which side of the pond you live on) technology spawned the Age of Electronics early in the 20th Century. Until the advent of solid-state electronics near mid-century, hollow-state devices were the only choice. But following the invention of the transistor (after their process fell to reasonable levels), within a couple of decades, the death of vacuum tubes was widely heralded. Yet here we are some five decades later, and hollow-state equipment is enjoying something of a comeback, especially in the music and high-end audio industries.
Many issues surround hollow-state audio:
Does it produce—as some claim—better sound? If so, is there science to back up these claims?
How do hollow-state circuits work?
How do you design hollow-state audio circuits?
If hollow-state equipment fails, how do you go about troubleshooting and repairing it?
Can we recreate some of the classic hollow-state audio devices for modern listening rooms and recording studios?
How can we intelligently modify hollow-state amplifiers to our taste?
These and other topics are covered in The State of Hollow State Audio.
The Elektor Audio DSP FX Processor combines an ESP32 microcontroller and an ADAU1701 Audio DSP from Analog Devices. Besides a user-programmable DSP core, the ADAU1701 has high-quality analog-to-digital and digital-to-analog converters built-in and features an I²S port. This makes it suitable as a high-quality audio interface for the ESP32.
Programs for the ESP32 can be created with Arduino, Platform IO, CMake or by using the Espressif IDF in another way. Programs for the ADAU7101 audio DSPs are created with the free visual programming tool SigmaStudio by dragging and dropping pre-defined algorithm blocks on a canvas.
Applications
Bluetooth/Wi-Fi audio sink (e.g. loudspeaker) & source
Guitar effect pedal (stomp box)
Music synthesizer
Sound/function generator
Programmable cross-over filter for loudspeakers
Advanced audio effects processor (reverb, chorus, pitch shifting, etc.)
Internet-connected audio device
DSP experimentation platform
Wireless MIDI
MIDI to CV converter
and many more...
Specifications
ADAU1701 28-/56-bit, 50-MIPS digital audio processor supporting sampling rates of up to 192 kHz
ESP32 32-bit dual-core microcontroller with Wi-Fi 802.11b/g/n and Bluetooth 4.2 BR/EDR and BLE
2x 24-bit audio inputs (2 V RMS, 20 kΩ)
4x 24-bit audio outputs (0.9 V RMS, 600 Ω)
4x Control potentiometer
MIDI in- and output
I²C expansion port
Multi-mode operation
Power supply: 5 V DC USB or 7.5-12 V DC (barrel jack, center pin is GND)
Current consumption (average): 200 mA
Included
1x ESP32 Audio DSP FX Processor board (assembled)
1x ESP32-PICO-KIT
2x Jumpers
2x 18-pin headers (female)
4x 10 KB potentiometers
Downloads
Documentation
GitHub
Easy and Affordable Digital Signal ProcessingThe aim of this book is to teach the basic principles of Digital Signal Processing (DSP) and to introduce it from a practical point of view using the bare minimum of mathematics. Only the basic level of discrete-time systems theory is given, sufficient to implement DSP applications in real time. The practical implementations are described in real time using the highly popular ESP32 DevKitC microcontroller development board. With the low cost and extremely popular ESP32 microcontroller, you should be able to design elementary DSP projects with sampling frequencies within the audio range. All programming is done using the popular Arduino IDE in conjunction with the C language compiler.After laying a solid foundation of DSP theory and pertinent discussions on the main DSP software tools on the market, the book presents the following audio-based sound and DSP projects:
Using an I²S-based digital microphone to capture audio sound
Using an I²S-based class-D audio amplifier and speaker
Playing MP3 music stored on an SD card through an I²S-based amplifier and speaker
Playing MP3 music files stored in ESP32 flash memory through an I²S-based amplifier and speaker
Mono and stereo Internet radio with I²S-based amplifiers and speakers
Text-to-speech output with an I²S-based amplifier and speaker
Using the volume control in I²S-based amplifier and speaker systems
A speaking event counter with an I²S-based amplifier and speaker
An adjustable sinewave generator with I²S-based amplifier and speaker
Using the Pmod I²S2 24-bit fast ADC/DAC module
Digital low-pass and band-pass real-time FIR filter design with external and internal A/D and D/A conversion
Digital low-pass and band-pass real-time IIR filter design with external and internal A/D and D/A conversion
Fast Fourier Transforms (FFT)
Learn KiCad with Peter Dalmaris
The Academy Pro Box "Design PCBs like a Pro" offers a complete, structured training programme in PCB design, combining online learning with practical application. Based on Peter Dalmaris’ KiCad course, the 15-week programme integrates video lessons, printed materials (2 books), and hands-on projects to ensure participants not only understand the theory but also develop the skills to apply it in practice.
Unlike standard courses, the Academy Pro Box provides a guided learning path with weekly milestones and physical components to design, test, and produce working PCBs. This approach supports a deeper learning experience and better knowledge retention.
The box is ideal for engineers, students, and professionals who want to develop practical PCB design expertise using open-source tools. With the added option to have their final project manufactured, participants complete the programme with real results – ready for use, testing, or further development.
Learn by doing
Build skills. Design real boards. Generate Gerbers. Place your first order. This isn’t just a course – it’s a complete project journey from idea to product.
You’ll walk away with:
Working knowledge of KiCad’s tools
Confidence designing your own PCBs
A fully manufacturable circuit board – made by you
What's inside the Box (Course)?
Both volumes of "KiCad Like a Pro" (valued at €105)
Vol 1: Fundamentals and Projects
Vol 2: Advanced Projects and Recipes
Coupon code to join the bestselling KiCad 9 online course by Peter Dalmaris on Udemy, featuring 20+ hours of video training. You'll complete three full design projects:
Breadboard Power Supply
Tiny Solar Power Supply
Datalogger with EEPROM and Clock
Voucher from Eurocircuits for the production of PCBs (worth €85 excl. VAT)
Learning Material (of this Box/Course)
15-Week Learning Program
▶ Click here to open
Week 1: Setup, Fundamentals, and First Steps in PCB Design
Week 2: Starting Your First PCB Project – Schematic Capture
Week 3: PCB Layout – From Netlist to Board Design
Week 4: Design Principles, Libraries, and Workflow
Week 5: Your First Real-World PCB Project
Week 6: Custom Libraries – Symbols, Footprints, and Workflow
Week 7: Advanced Tools – Net Classes, Rules, Zones, Routing
Week 8: Manufacturing Files, BOMs, and PCB Ordering
Week 9: Advanced Finishing Techniques – Graphics, Refinement, and Production Quality
Week 10: Tiny Solar Power Supply – From Schematic to Layout
Week 11: Tiny Solar Power Supply – PCB Layout and Production Prep
Week 12: ESP32 Clone Project – Schematic Design and Layout Prep
Week 13: ESP32 Clone – PCB Layout and Manufacturing Prep
Week 14: Final Improvements and Advanced Features
Week 15: Productivity Tools, Simulation, and Automation
KiCad Course with 18 Lessons on Udemy (by Peter Dalmaris)
▶ Click here to open
Introduction
Getting started with PCB design
Getting started with KiCad
Project: A hands-on tour of KiCad (Schematic Design)
Project: A hands-on tour of KiCad (Layout)
Design principles and PCB terms
Design workflow and considerations
Fundamental KiCad how-to: Symbols and Eeschema
Fundamental KiCad how-to: Footprints and Pcbnew
Project: Design a simple breadboard power supply PCB
Project: Tiny Solar Power Supply
Project: MCU datalogger with build-in 512K EEPROM and clock
Recipes
KiCad 9 new features and improvements
Legacy (from previous versions of KiCad)
KiCad 7 update (Legacy)
(Legacy) Gettings started with KiCad
Bonus lecture
About the Author
Dr. Peter Dalmaris, PhD is an educator, an electrical engineer and Maker. Creator of online video courses on DIY electronics and author of several technical books. As a Chief Tech Explorer since 2013 at Tech Explorations, the company he founded in Sydney, Australia, Peter's mission is to explore technology and help educate the world.
What is Elektor Academy Pro?
Elektor Academy Pro delivers specialized learning solutions designed for professionals, engineering teams, and technical experts in the electronics and embedded systems industry. It enables individuals and organizations to expand their practical knowledge, enhance their skills, and stay ahead of the curve through high-quality resources and hands-on training tools.
From real-world projects and expert-led courses to in-depth technical insights, Elektor empowers engineers to tackle today’s electronics and embedded systems challenges. Our educational offerings include Academy Books, Pro Boxes, Webinars, Conferences, and industry-focused B2B magazines – all created with professional development in mind.
Whether you're an engineer, R&D specialist, or technical decision-maker, Elektor Academy Pro bridges the gap between theory and practice, helping you master emerging technologies and drive innovation within your organization.
From Theory to Practical Applications in Wireless Energy Transfer and Harvesting
Wireless power transmission has gained significant global interest, particularly with the rise of electric vehicles and the Internet of Things (IoT). It’s a technology that allows the transfer of electricity without physical connections, offering solutions for everything from powering small devices over short distances to long-range energy transmission for more complex systems.
Wireless Power Design provides a balanced mix of theoretical knowledge and practical insights, helping you explore the potential of wireless energy transfer and harvesting technologies. The book presents a series of hands-on projects that cover various aspects of wireless power systems, each accompanied by detailed explanations and parameter listings.
The following five projects guide you through key areas of wireless power:
Project 1: Wireless Powering of Advanced IoT Devices
Project 2: Wireless Powered Devices on the Frontline – The Future and Challenges
Project 3: Wireless Powering of Devices Using Inductive Technology
Project 4: Wireless Power Transmission for IoT Devices
Project 5: Charging Robot Crawler Inside the Pipeline
These projects explore different aspects of wireless power, from inductive charging to wireless energy transmission, offering practical solutions for real-world applications. The book includes projects that use simulation tools like CST Microwave Studio and Keysight ADS for design and analysis, with a focus on practical design considerations and real-world implementation techniques.
For Speed, Area, Power, and Reliability
This book teaches the fundamentals of FPGA operation, covering basic CMOS transistor theory to designing digital FPGA chips using LUTs, flip-flops, and embedded memories. Ideal for electrical engineers aiming to design large digital chips using FPGA technology.
Discover:
The inner workings of FPGA architecture and functionality.
Hardware Description Languages (HDL) like Verilog and VHDL.
The EDA tool flow for converting HDL source into a functional FPGA chip design.
Insider tips for reliable, low power, and high performance FPGA designs.
Example designs include:
Computer-to-FPGA UART serial communication.
An open-source Sump3 logic analyzer implementation.
A fully functional graphics controller.
What you need:
Digilent BASYS3 or similar FPGA eval board with an AMD/Xilinx FPGA.
Vivado EDA tool suite (available for download from AMD website free of charge).
Project source files available from author’s GitHub site.
Design Guide for EMI Filter Design, SMPS & RF Circuits The book focuses on the selection of components, circuitry and layout recommendations for a wide array of magnetics components, always keeping in mind an EMC point of view. Contents Basic principles The most important laws and foundations of inductive components, equivalent circuit diagrams and simulation models give the reader a basic knowledge of electronics. Components This chapter introduces inductive components and their special properties and areas of use. All relevant components are explained, from EMC components and inductors to transformers, RF components, circuit protection components, shielding materials and capacitors. Applications In this chapter, the reader will find a comprehensive overview of the principle of filter circuits, circuitry and numerous industrial applications that are explained in detail based on original examples.
