In these projects, I enjoy combining practical utility of the outcome, embedded software engineering, electronics engineering (incl. PCB layout), (SMD) electronics manufacturing and a little mechanical engineering and 3D printing. Performing the entire realization chain from requirements identification to a finished device is what makes this fun for me. Every project is an opportunity to learn new things!

These are a few examples of projects I’ve completed:

Home environment and energy monitor

What doesn’t get measured, doesn’t get done! So to seduce ourselves to be more energy-conscious, I’ve made a system that monitors key parameters of our household: energy consumption/production and environmental parameters (relative humidity, temperature, barometric pressure). The system consists of multiple devices: ESP826-based temperature/humidity sensors in most rooms, a parasitically powered and ATTiny3227-based smart meter reader unit, an ESP32-based control unit with e-paper display, a database backend (MariaDB) and a set of web pages (using PHP and chart.js) to make the information accessible from any device.

Stereo channel selector and attenuator

This is a classic “preamplifier” project that extends my father’s old 1970s Pioneer integrated stereo with multiple, volume-controlled inputs. It includes an nRF24-based remote control system, an ATMega328P controller in the main unit and an ATTiny3227 in the remote control unit. Software written in Arduino C++.

Color enlarger exposure system

Photography is my Big Passion, and in particular enlarging color negatives. I turned my old Durst 138 black & white enlarger into a modern, LED-equipped color enlarger with an exposure controller tailored to my needs. The system consists of a power supply unit, entirely home-brew high-power SMD RGB LED source and an ESP32-based controller unit. I’ve made many hundreds of color prints with this system already, but it’s continuously involving as I see new ways to optimize its performance. A series of blogs on tinker.koraks.nl has attracted attention from across the globe, including a feature on Hackaday.

Photographic darkroom lighting system

For my photographic darkroom I required a lighting system that offers a pleasurable work environment, color rendition accuracy as well as safelight conditions for handling photographic materials. For this purpose, I made a system employing self-made light bars with LED strips chosen for to fulfill these various requirements. The bars are powered by separate controller units which form a wireless network (nRF24-based). Control is through an existing remote control unit that was integrated into the system as well as a rudimentary web page to control the various lighting programs.

Cat detector

A motion detector that controls the pump in a pet drinking fountain. Based on a tiny STM8 microcontroller (programmed with Cosmic C / STDev) and a PIR motion sensor. It features several software safety features to ensure dependable operation of the drinking fountain.

UV exposure controller with integrator

For making alternative process photographic prints (carbon transfer, salted paper, cyanotype etc.) as well as exposing PCB’s, I use UV LEDs. I currently use off-the-shelf UV floodlights, and to make these easier to use, I’ve built a timer/controller with a UV sensor/light integrator. Exposures can be controlled by setting time, or by setting target “exposure units” and positioning the UV sensor in near the exposed object (print/PCB). Since the switchable output is a (modified) wall outlet, any exposure unit (DIY or off-the-shelf) can be plugged into it at will.