Cable crosssections

Just a short summary of the most important data about cable cross sections and current carrying capabilities. Please note that this article is not a substitute of looking up in your local regulations - I just keep these values here to have a quick guess at hand when thinking about such stuff.

Some notes on 3D printing

Just a collection of comments on 3D printing

Building a LoRA WAN gateway (and supplying data for the things network)

The following article leads the reader through building an LoRA-WAN gateway from an iMST ic880a concentrator board and an RaspberryPi. Optionally is shows the reader how to add GPS, enable remote configuration via the tinc VPN daemon and via a TOR stealth hidden service.

Using Sonoff basic switches with own firmware

Example how to flash Sonoff basic switches with custom firmware (using cli tools or the Arduino IDE)

Getting started with STM32F401RE Nucleo starter board on FreeBSD

How to get started with the STM32F401RE nucelo development board on FreeBSD with gcc and openocd

Linear stepper motor control - A summary

A short summary of the algorithms required for linear accelerated and decelerated stepper motor control on microcontrolers.

Building a simple 3D printer (and what turned out to be not so simple)

This article describes some of the ideas and thoughts during building my first FDM printer and which lessions have been learned from that project.

I2C communication between RaspberryPi and an AVR based I2C slave

This article explains how to use an AVR as I2C slave device (basically how to set registers for the TWI controller) and how to interface that to an RaspberryPi running FreeBSD

Building an I2C controllable stepper driver board with DRV8825 breakout boards and ATMega328p

This is the description of a small carrier board for two DRV8825 breakout boards (or compatible) that are controlled by an AVR (ATMega328p) which runs a small (linear) motion processor that gets it's commands via I2C.

Authenticating and signing using Austrias citizen card

A short summary on how to embed authentication and generally signing with the Austrian citizien card

Simple digital filter design

A short tutorial on designing and applying digital filters.

Using piezo disks for automatic bed leveling on 3D printers

Description of an easy way of using piezo disks as touch sensors to perform bed leveling with 3D printers or other CNC machines. This blog entry describes the most basic possible way without much external circuits (only an ATtiny13A and two resistors are used)

Using Sonoff T4EU1C non-neutral switches with own firmware

15 Jan 2020 - tsp

A short review about the T4EU1C Sonoff Switch as well as an example how to flash Sonoff basic switches with custom firmware

Neuronal network basics

25 Feb 2020 - tsp

A short introduction into neuronal networks and backpropagation

3D printing NACA airfoil profiles

12 Jun 2020 - tsp

Mini Blog-Post that describes modelling 4 digit NACA airfoil profiles in OpenJSCAD

Capacitance measurement with AVR (simple, fast)

09 Jul 2020 - tsp

Mini article about the measurement of capacitance with AVRs with a minimum of external components (in it's most extreme form none external components exploiting the gate capacitance of the micro-controllers input)

Automatic plant watering and illumination (smallest version)

26 Jul 2020 - tsp

In this blog article I'm describing a small automated plant watering solution that's used indoor to grow basil, capsicum and chili pepper indoor.

How stuff works - Line power distribution and protective measures in Europe (consumer side)

03 Aug 2020 - tsp

Since it seems to be a huge mystery to many people this blog post tries to summarize some of the parts relevant to the consumer side of power grid systems.

A simple home-built epoxy counter-top

09 Aug 2020 - tsp

Short blog post about the casting of a simple epoxy countertop with embedded sink.

Dipl.-Ing. Thomas Spielauer, Wien (

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