We're testing out an I2C-to-solenoid driver today. It uses an MCP23017 expander. We like this particular chip for this usage because it has push-pull outputs, making it ideal for driving our N-channel FETs and flyback diodes. The A port connects to the 8 drivers, while the B port remains available for other GPIO purposes. For this demo, whenever we 'touch' a pin on port B to ground, the corresponding solenoid triggers provide an easy way to check speed and power usage.
How to Build an ESP32 Stress Detector Using a MAX30100 Sensor
Most people think stress detection requires expensive medical equipment or professional polygraph systems. Surprisingly, modern microcontrollers have become powerful enough to monitor several physiological indicators associated with stress using affordable components.
👉 Read the complete ESP32 Biometric Stress Detector tutorial on Quartz Components
Learn how to build an ESP32 stress detector using a MAX30100 sensor, HRV analysis, and capacitive touch sensing for real-time stress monitor
One interesting example combines an ESP32 Development Board with a MAX30100 Heart Rate Sensor to create a real-time biometric stress detector. By monitoring heart rate, heart rate variability (HRV), and skin conductance, the system can estimate a user's stress level and generate a live stress score.
The Science Behind It
When a person experiences stress, the body's autonomic nervous system responds almost instantly. Several measurable changes occur:
✔ Heart rate increases
✔ Heart rate variability decreases
✔ Skin conductivity rises due to increased perspiration
These same physiological responses have been used for decades in polygraph and biometric monitoring systems. The difference is that today's maker-friendly hardware makes experimentation far more accessible than ever before.
Why ESP32 Is Perfect For The Job
The ESP32 isn't just another microcontroller.
Its built-in Wi-Fi, Bluetooth, dual-core processor, and capacitive touch sensing capabilities allow it to process biometric data in real time while communicating with external sensors such as the MAX30100.
Even more interesting, the ESP32's touch pins can be used to estimate skin conductivity without requiring a dedicated GSR module, making the entire project both affordable and compact.
Beyond Simple Heart Rate Monitoring
Most DIY health projects stop at displaying BPM values.
A more advanced approach involves combining multiple biometric signals into a single stress index. By comparing live readings against a personalized baseline, the system can identify changes that may indicate elevated stress levels.
This multi-sensor approach delivers significantly more meaningful insights than relying on heart rate alone.
What Can You Learn From This Project?
Building a biometric stress detector introduces several valuable engineering concepts:
I2C sensor communication
Signal filtering techniques
HRV calculations
Capacitive touch sensing
Embedded data processing
Real-time physiological monitoring
Whether you're a student, maker, IoT enthusiast, or electronics hobbyist, projects like these provide a practical introduction to biomedical sensing and wearable technology.
Want To Build One Yourself?
We've created a complete step-by-step guide covering:
✅ Components required
✅ Circuit connections
✅ ESP32 source code
✅ Stress scoring algorithm
✅ Calibration process
✅ Real-time visualization setup
You can find the full tutorial, component list, and project resources at Quartz Components, where we regularly publish hands-on electronics, IoT, robotics, and ESP32-based projects.
From Coil to Component: Watching Nickel Tabs Being Punched
The Life of a Nickel Tab
There's something satisfying about watching metal transform.
I set up a camera by the press last week to capture how Nickel Tabs actually get made. Not the polished marketing version — just the raw process. Coil feeds in, die comes down, parts come out.
What you're seeing:
A coil of pure nickel, 0.15mm thick, feeding into a progressive stamping die. At full speed, this press runs about 300 strokes per minute. Each stroke produces multiple Nickel Tabs, depending on the die design.
The details matter:
The material position is controlled to ±0.02mm
The punch-die clearance is optimized for clean edges (critical for Nickel Tab for SMT applications)
Scrap is cut and separated automatically
Why stamping?
For Custom Laser Welding Nickel Tab requirements, the starting point matters. A consistently formed tab means consistent contact during welding. No warping. No variation. Just repeatable quality, thousands of times per hour.
I'm planning more videos like this — different materials, different processes. Anything specific you'd like to see? Drop it in the comments. 👇
Seeing that people have really appreciated something I made has been some sunshine at the end of a very tough week. Thanks @hacksterio Posted @withregram • @hacksterio The term "cyberdeck" originated in the '80s with William Gibson's Neuromancer novel. Nothing is more '80s than a boombox, which is why this cyberdeck is so great. Its enclosure is a late '70s Sanyo radio with built-in cassette tape deck, but it looks pure '80s. Inside are a @raspberrypi and @arduino.cc Pro Micro. Outside are a 7" LCD, a 1502 LCD, an analog VU meter, a keyboard, and even a joystick built into the original tuner knob. // 📻 bit.ly/boombox-cyberdeck // 📷 cyberdeck.cafe/mix/sanyo #hackster #raspberrypi #arduino #arduinopromicro #sparkfun #boombox #cyberdecks #cyberdeck #vumeter #keyboard #joystick #cassettetapes #casetteplayer #retrotechnology #retrotech #diyelectronics #engineering https://www.instagram.com/p/CUN_RbvsE5f/?utm_medium=tumblr
I built my first MIDI controller - a budget version of the “MIDI Fighter” 🤺 Had lots of fun learning how to make this from scratch and it has inspired me to continue exploring the world of DIY Electronics and music instrument design ✨ … #midicontroller #arduino #arduinoproject #musicinstrument #diyelectronics #electronics #diysynth https://www.instagram.com/p/CUrzIjcF4z_/?utm_medium=tumblr
