Designing IoT Wireless Sensor Nodes
Mahesh Balan outlines practical strategies for building tiny IoT wireless sensor nodes that run on harvested energy. The post explains using small solar cells with coin-cell or supercapacitor buffering, pairing sensors with Bluetooth Low Energy for short-range telemetry, and choosing PMICs with ultra-low quiescent and startup power. A Cypress PMIC example shows operation can be sustained under low-brightness conditions near 100 lx.
VERY Fast Japanese Sumo Robots
Japanese sumo robots can be oddly mesmerizing, and this short post captures that perfectly. Stephane Boucher shares a quick reaction to a video and points out the parts embedded engineers would want to hear about, like the sensors, microcontroller, algorithms, and design challenges behind the machine. It is more of a teaser than a teardown, but it makes a strong case for a deeper technical writeup.
The Other Kind of Bypass Capacitor
Most engineers treat bypass capacitors as supply decoupling, but Jason Sachs digs into the other kind: a capacitor placed in the feedback path to tame unpredictable high-frequency plant behavior. He walks through real examples, Bode plots, and a simple RC model to show how the cap forces unity-gain feedback at high frequency, stabilizing switching regulators and wideband amplifiers while revealing the speed versus stability tradeoff.
Unmanned Ground Vehicles - Design Considerations for Snow and Cold Environments
Winter conditions expose UGV weaknesses: snow, ice and extreme cold change traction, sensor performance, batteries and lubrication. This post walks through snow mechanics, ground-pressure tradeoffs for wheels versus tracks, and practical mitigations like heaters, insulation, sensor covers and low-temperature lubricants. If you design autonomous ground systems for cold climates, these engineering checks and referenced studies will help you avoid mission-ending failures.
Basic Sensors for an Autonomous Vehicle
A compact primer on inexpensive sensors you can use to help a small autonomous vehicle sense its surroundings. The post walks through line follower modules, several switch types for bumpers, ultrasonic PING sensors and passive infrared units, with practical notes on mounting and common pitfalls like reversed pins and unreliable returns on rough surfaces.
Metal detection: building the detector
Fabien Le Mentec turns a bench-validated BFO stage into a field-ready metal detector using scavenged parts and straightforward fabrication. He moves the circuit from breadboard to a through-hole prototyping PCB, swaps the Arduino Nano for a lower-power Mini, and builds an ABS control box with buttons and a buzzer. The build uses a 2S LiPo pack with a 5V LDO and a nonmagnetic coil mount, with practical notes on tradeoffs and safety.
Metal detection: beat frequency oscillator
Fabien Le Mentec walks through a practical beat frequency oscillator metal detector, from the LC oscillator theory to the Arduino-based frequency counter. He shows how changes in coil inductance reveal nearby metal, and why capacitor choice matters when you want a stable detector. The post focuses on the BFO sensing stage, with enough detail to help you build and test one yourself.
A quick look at the Line Follower Vehicle
A line follower vehicle boils down to four parts: sensors, steering, chassis, and processing. This quick overview explains sensor counts and placement, the tradeoffs between Ackerman and skid-steer steering, and simple processing choices from comparators to an Arduino Uno. Read on for practical tips to pick sensors, arrange the chassis, and avoid common pitfalls when building or tuning a basic LFV.
Motion Sensor with Raspberry Pi and MPU6050 - Part 1
This blog will help you build your own, low cost 3-axis motion sensor using Raspberry Pi and Invensense MPU6050.
Handling latency in data acquisition systems
In recent projects, I found myself working with data acquisition systems. For instance: PCIe/10GbE readouts for 2D XRay detectors (RASHPA slides, RASHPA paper) instruments mixing 1D signal acquisition and triggering, microcontroller based system for audio transmission: (NRF spearker)
Two Capacitors Are Better Than One
Jason Sachs revisits a simple stacked RC trick that dramatically reduces DC error from capacitor insulation leakage in long time-constant filters. Splitting one RC into two stages forces most of the DC drop onto the lower capacitor, squaring the remaining error while changing the effective pole locations. The post walks through the math, practical component tradeoffs, and when to prefer a digital approach.
How to Analyze a Differential Amplifier
Jason Sachs walks through the algebra and intuition behind the classic four-resistor differential amplifier. He derives the exact output equation, isolates error terms from resistor mismatch and op-amp imperfections, and explains why common-mode gain depends on mismatch not on the differential gain. Read this for clear formulas, modal insight into common-mode versus differential-mode, and practical steps to reduce offsets in real designs.
The Most Annoying Sound
Independent consultants often face requests and requirements that go beyond the technicalities of software and hardware. Designing user interfaces is a common example, and even though most of us are not UI experts, we still have to get it right, otherwise the users may get annoyed, and the product will fail. However, what happens when we're asked explicitly to annoy users? Here's a true story about such a case.
Introduction to Microcontrollers - Button Matrix & Auto Repeating
Wiring every button to its own GPIO gets expensive fast, so Mike Silva shows how to read a 4x4 keypad with only eight pins using matrix scanning. He then builds the raw scan into a debounced state machine, adds auto-repeat, and even extends it to a two-stage repeat rate. The result is a practical, code-heavy walkthrough for turning a keypad into clean button events on AVR and STM32.
10 Items of Test Equipment You Should Know
Jason Sachs walks through ten often-overlooked pieces of test gear that make debugging embedded hardware faster, safer, and more precise. From clamp-on and Rogowski current probes to spring-tip probes, IC test clips, and compact DAQ systems, each tool targets a common bench frustration. Practical buying notes and use cases help you choose tools that save time and reduce guesswork.
VolksEEG Project: Initial Hardware Architecture
The VolksEEG prototype pairs an Adafruit Feather nRF52840 Sense MCU with an ADS1299 analog front end, organized into non-isolated and isolated domains to protect patients. The post explains why isolation is required, which chips bridge the domains, and why simple, high-level power and signal diagrams help clarify the KiCad schematics for engineers and reviewers.
How to Arduino - a video toolbox
Lonnie Honeycutt is kicking off a practical Arduino video series aimed at hobbyists who want the fastest, simplest way to get things working. The first few lessons cover the Arduino IDE, breadboards, a 16x2 LCD, servos, potentiometers, and analogRead. He also shares a behind-the-scenes look at his multi-camera filming setup and how it helps him focus on the project instead of the shot.
How to use I2C devices in (Apache) NuttX: Adding support for an I2C device in your board
You can add an I2C sensor to NuttX with a few file edits, menuconfig tweaks, and a standard build-and-flash cycle. This guide shows how the BMP280 barometer was integrated into the Raspberry Pi Pico bringup by copying and adapting an existing board driver, wiring the sensor to I2C0, enabling the BMP280 option in menuconfig, and compiling and flashing the resulting nuttx.uf2. It includes exact wiring and build tips.
Getting Started With Zephyr: Writing Data to EEPROM
In this blog post, I show how to implement a Zephyr application to interact with EEPROM. I show how the Zephyr device driver model allows application writers to be free of the underlying implementation details. Unfortunately, the application didn't work as expected, and I'm still troubleshooting the cause.
Someday We’ll Find It, The Kelvin Connection
Low-ohm measurements will fool your multimeter unless you use Kelvin connections. Jason Sachs walks through four-wire sensing using a current-limited supply and two DMMs, explains thermoelectric and connector-related errors, and shows why schematics and PCB layout must reflect Kelvin sense pads to avoid subtle measurement and circuit problems.
10 Items of Test Equipment You Should Know
Jason Sachs walks through ten often-overlooked pieces of test gear that make debugging embedded hardware faster, safer, and more precise. From clamp-on and Rogowski current probes to spring-tip probes, IC test clips, and compact DAQ systems, each tool targets a common bench frustration. Practical buying notes and use cases help you choose tools that save time and reduce guesswork.
How to Analyze a Differential Amplifier
Jason Sachs walks through the algebra and intuition behind the classic four-resistor differential amplifier. He derives the exact output equation, isolates error terms from resistor mismatch and op-amp imperfections, and explains why common-mode gain depends on mismatch not on the differential gain. Read this for clear formulas, modal insight into common-mode versus differential-mode, and practical steps to reduce offsets in real designs.
How to Arduino - a video toolbox
Lonnie Honeycutt is kicking off a practical Arduino video series aimed at hobbyists who want the fastest, simplest way to get things working. The first few lessons cover the Arduino IDE, breadboards, a 16x2 LCD, servos, potentiometers, and analogRead. He also shares a behind-the-scenes look at his multi-camera filming setup and how it helps him focus on the project instead of the shot.
Optimizing Optoisolators, and Other Stories of Making Do With Less
Jason Sachs digs into how to squeeze speed and reliability from low-cost optoisolators, showing practical tweaks that often outperform default datasheet usage. He mixes hands-on circuits — using 4N35 base-emitter resistors, Schottky clamps, input speedup caps, and output buffering — with transistor-switching theory and a cautionary production story to show when to optimize and when to splurge on pricier isolators.
Metal detection: beat frequency oscillator
Fabien Le Mentec walks through a practical beat frequency oscillator metal detector, from the LC oscillator theory to the Arduino-based frequency counter. He shows how changes in coil inductance reveal nearby metal, and why capacitor choice matters when you want a stable detector. The post focuses on the BFO sensing stage, with enough detail to help you build and test one yourself.
Isolated Sigma-Delta Modulators, Rah Rah Rah!
Analog isolation can blow up DAQ budgets, but isolated sigma-delta modulators let you send a single 1-bit stream and a clock across the barrier, keeping costs down. Jason walks through Avago, TI, and Analog Devices parts, explains sigma-delta noise shaping in plain terms, and calls out the real engineering work: converting a 10–20 MHz bitstream into usable samples with sinc/CIC decimators or FPGA filtering.
Reverse engineering wireless wall outlets
Fabien Le Mentec reverse engineers a cheap set of wireless wall outlets to add them to his BANO home automation while avoiding uncertified mains hardware. He uses PCB inspection to identify a Holtek MCU and RF83C, captures 433.92 MHz OOK signals with an RTL-SDR and ookdump, then replays commands using an RFM22 in direct mode controlled by an ATmega328P. The post explains frame structure and links to a working GitHub implementation.
Have You Ever Seen an Ideal Op-Amp?
Forget the ideal op-amp fantasy, Jason Sachs walks through the practical nonidealities that make textbook gain formulas fail in real circuits. Using the uA741C and TLC081C as examples, he explains offset voltage, input bias and offset currents, common-mode and supply rejection, gain-bandwidth and slew-rate limits, plus capacitive loading, RF rectification and overload recovery. Read to learn which datasheet specs matter and why.
Voltage Drops Are Falling on My Head: Operating Points, Linearization, Temperature Coefficients, and Thermal Runaway
A lot of the neat, tidy diode and transistor rules you learned in school are really just approximations. Jason Sachs shows how operating points, linearization, and temperature coefficients give you a better mental model for real circuits, then uses that framework to explain why thermal runaway happens. Along the way, he connects the theory to practical device behavior, op-amp output stages, and the design tricks that keep parts from letting out the magic smoke.
C++ on microcontrollers 4 – input pins, and decoding a rotary switch
Wouter van Ooijen shows how to extend a small C++ I/O library for microcontrollers to support input pins and mixed I/O, and how to decode a rotary switch reliably. The post walks through a safe class hierarchy for input, output, and bidirectional pins, then builds a quadrature decoder with a saturating counter and an HC595 seven-segment demo you can run on LPCXpresso hardware.
