ESP32 I2S-PDM Interface for Digital Guitar Pedal Application

The PDM (pulse-density modulation) has been widely used in the current technology of audio signal conversion (from analog to digital) because its simplicity while achieving high quality conversion. This technology is widely used in digital microphone, and it is basically a sigma delta modulator circuit which is used in many modern audio codec chip as well. It is an interesting […]

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Types of AC/DC Power Supply Adapter Circuits and How to Use Them

Power supply is one of the main element in every electronic circuit, and the right AD/DC adapter circuit should be chosen if we want our device to accept power line voltage as the main supply. There several types of AC/DC adapter circuits, transformer-less (non-isolated), step-down transformer, and switched-mode power supply adapter. The schematic diagram of the circuits and how to […]

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Full-Adder Circuit, The Schematic Diagram and How It Works

Introduction Full-adder circuit is one of the main element of arithmetic logic unit. It is the full-featured 1-bit (binary-digit) addition machine that can be assembled to construct a multi-bit adder machine. We can say it as a full-featured addition machine since it has “carry input” and a “carry-output”, in addition to the two 1-bit data inputs and one 1-bit data […]

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ESP32-A1S Guitar Multi-Effect Engine with Microphone and MIDI I/O

Since the release of ESP32 by Espressif, many application-specific modules based on this chip are produced. For example, Ai-Thinker produce image processing module with artificial intelligence support for image recognition. In the audio processing area, one interesting product by Ai-Thinker is the ESP32-A1S module. Because of the integrated AC101 codec inside, this module enable very compact and low cost solution […]

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DIY Reverb Pedal Circuit: Spring-Hall Reverb with PT2399 IC

Introduction to Reverberation Before getting into the design of DIY reverb pedal circuit, lets see the concept of reverberation first. Real reverberation happens in a performance chamber when the walls and every object inside reflects the sound back and forth. As the sound bounces back and forth in three dimensional space, the reflections creates more and more complex pattern. The […]

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DIY Multi-Effect Pedal Platform is Now Low-Cost!

DIY Multi-Effect Pedal and Today’s Advanced Electronics Digital DIY multi-effect pedal is an expensive things in the past, but the advance of today’s digital electronics brings new hopes for many things. Because now there are many choices for low cost and high performance DSP microcontrollers, now I think we can implement a DIY multi-effect pedal with much lower cost than […]

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DIY Digital Effect Pedal Platform Review: The Top 9

9 DIY Digital Effect Pedal Platform List To start researching on DIY (do-it-yourself) digital  effect pedal for the next project, let’s see the list first. Take a look at some popular platforms to compare their specifications and prices, here are some: UNO – Electrosmash’s pedalSHIELD UNO MEGA – Electrosmash’s pedalSHIELD MEGA DUE – Electrosmash’s pedalSHIELD DUE Electrosmash’s Pedal Pi Openmusiclabs’s […]

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Multi-Channel Expansion Oversampling: 15Bit from 12Bit ADC

Introduction: Analog-to-Digital Conversion Oversampling Every analog-to-digital conversion is designed for specific resolution depending on the bit (binary digit) width of the conversion. For example, a 10 bit ADC with 5V reference would have 5V/1024 resolution or about 4.883 mV. The intrinsic error related to the resolution is the digital-quantization error  of ±0.5 bit. In other words, it should produce only […]

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16-bit Audio PWM by Dual 8-bit PWM with Auto Calibration

Introduction: PWM (Pulse-Width Modulation) for Digital Audio Conversion Pulse width modulation (PWM) technique has been widely used for converting digital audio stream into audio signal since it is very simple and easy to implement. Many low-cost micro controllers include dedicated PWM controllers as their standards, and many engineers use it for many purposes. In this article, we present the solution […]

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Arduino HM-936D Soldering Station Controller Development

A. Introduction: The 936 Soldering Station Series in The Market With the popularity of specific brand’s soldering station labeled with 936-series, many manufacturers (mostly Chinese companies) make benefits by producing the counterfeit products with the generic names “936 series” soldering station. It is a good things that their parts are widely available on the online marketplace, as shown in the […]

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Adjustable Frequency Flip-Flop Circuit Using Inverter Gate

This flip-flop circuit uses one potentiometer and one capacitor as the frequency determining components. The assembled circuit is shown in the Figure 1, and the schematic diagram of the circuit is shown in the Figure 2. The circuit consists of one integrated circuit of inverter gates (4069 CMOS or  74C04), one electrolytic capacitor, two resistors, two LEDs, and one potentiometer. […]

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