last modified: October 23, 2025
Posted on 2021-04-03— 3D Printing, Projects
I walk through the sensor board I designed for the pet feeder, explaining the position sensor, four fill sensors, and why component choices (like the 100kΩ resistor) matter. I keep the design simple and practical — read the full post for schematics, measurements, and ordering details.
Posted on 2021-03-31— 3D Printing, Fail, Projects
I ran into unexpected problems testing the fill-sensor panel: light was travelling through the printed turntable and confusing one sensor. I walk through how I diagnosed the issue, which fixes failed, and two practical approaches I’m testing — read on for the full troubleshooting and print updates.
Posted on 2021-03-15— 3D Printing, Common
I've assembled the new input boards for the pet feeder and I'm testing the sensors—940nm IR LEDs paired with phototransistors. I share photos of the board top and underside, the turntable mounting, and revision notes. Please read on if you'd like to see the test results and next steps.
Posted on 2020-12-19— Projects
I published a small command-line tool to read the Sensirion SGP30 air-quality sensor on a Raspberry Pi. I explain usage, options, and how to build and install the C tool so you can get JSON CO2/TVOC output. If it helps, please read the full post for details.
Posted on 2020-12-13— Software
I built a small compiled command-line tool to read SHT31 temperature and humidity over I2C on a Raspberry Pi. It emits simple JSON for easy parsing in scripts. If you're using an SHT31 sensor or automating reads, read the full post for usage, build and install steps.
Posted on 2019-02-23— Projects
I guide you through building a compact particle sensor node using a Raspberry Pi Zero W and a minimal custom shield, with published Gerbers, STL files and example code. I keep the design simple and extendable—if you'd like to build your own networked air-quality node, read the full post for parts, assembly and setup.
Posted on 2017-04-29— Projects
I describe making a small alpha batch of my low-cost plant-watering sensor: ordering parts, prepping and soldering wires, testing PCB assembly with stencils, and solving sealing with epoxy. If you’re interested in practical prototyping tips and lessons learned, please read the full post for photos and detailed steps.
Posted on 2017-04-12— Projects
I began a second long-term test of my plant watering sensor to confirm it tracks moisture cycles after watering and drying. I'm focusing on logging and sealing the sensor's foot for repeatable readings. If you're curious about methods and results, please read the full post and share feedback.
Posted on 2017-03-09— How and Why
I walk you through designing the final PCB for a low-cost plant watering sensor: choosing tools, shaping the board, iterative layouts, BOM decisions, assembly planning and unit-cost calculations. If you want practical steps and cost details, please read the full post to follow the next parts.
Posted on 2017-03-03— How and Why
In part three I assemble and test the prototype PCB, set ATtiny13A fuses, and refine user interaction and firmware plans. I cover LED display choices, power measurements and a modular firmware approach. If you’re building a low-cost plant sensor, read the full post for practical steps and diagrams.
Posted on 2017-02-14— How and Why
I take you through part two of my cheap plant-watering sensor project, testing a prototype: power draw, LED impact, oscillator and MCU startup timing, voltage-divider checks, firmware inputs, and PCB preparation. If you want to see the detailed measurements and next steps, I invite you to read the full post.
Posted on 2017-02-08— How and Why
I walked through designing a cheap capacitive plant watering sensor, from goals and measurement options to component selection and early prototypes. I explain why I chose a CR2032‑powered op‑amp oscillator, ATtiny MCU and low‑power timer. If you’re curious, read the full post for details and test results.
Posted on 2015-09-01— Projects
I fixed a timing bug and logged AM2302 (DHT22) readings every 10 seconds until memory filled. The data revealed temperature precision limits (0.1°C) and jitter that causes humidity jumps. I walk through the patterns, implications for real‑time displays, and link the CSV/Excel—please read the full post for details.