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Welcome to my website! I’m Michał Słomkowski, callsign SP3OHM. I work full-time as a Java/Kotlin backend developer and Linux system administrator. Here, I usually write about my tinkering endeavors, electronics, hardware, software, amateur radio and mechanical hacks. I live in Poznań, Poland. If you want to contact me for any reason, you can find the details on the About page.
There are 36 articles on this website. The most recent articles have been published or updated:
The HF transceiver I couldn't finish
As a teenager, I attempted to build a 0–30 MHz transceiver from scratch, going through three design iterations. None were completed; design errors and the lack of more advanced RF measurement equipment overwhelmed me. Still, I include the description here as a monument to that fascination.
MikroTik: T-Mobile Polska over Vectra DOCSIS
How to replace an ISP-issued router with a MikroTik on T-Mobile Polska delivered over a Vectra DOCSIS cable network. Covers obtaining PPPoE credentials, configuring VLAN 35 required by T-Mobile, and RouterOS setup including MTU handling for baby giant frames.
Meshtastic on Orange Pi Zero 3 with E22-900M30S
Testing a Meshtastic node with an Orange Pi Zero 3 and an E22-900M30S (SX1262) LoRa module. I describe Armbian, SPI, GPIO configuration, and building an 868 MHz ground-plane antenna.
FFmpeg on Debian with NVIDIA NVENC/NVDEC/CUVID
A quick guide for FFmpeg with NVIDIA GPU support on Debian 13, including compilation and examples of hardware-accelerated video transcoding.
Isolated power supply and 230 V testing station
I describe the design and construction of an isolated AC/DC power supply and testing station built from a salvaged East German variac. It features variable AC output (0–330 V) and DC output (0–450 V) and integrates digital meters and safety features.
Server resetter from Waveshare Ethernet Relay module
A quick project connecting a Waveshare Modbus Ethernet relay module to a motherboard's reset pin to have an emergency remote reset button.