Nixie Tube Clock with Seconds

Building a nixie-tube clock is a project that I wanted to do for ages. The clock was build around IN-12b Tubes (I got them for cheap from eBay) and the TPIC6B595 shift register. The schematic is pretty straightforward. The clock consists of 3 PCBs with 2 tubes each. Because of…

Unit Tests, Android Tests, and Code Coverage

Effective testing is one of the biggest challenges in the process of software engineering. Especially testing Android applications can be tricky because the code often calls Android specific methods which a normal unit-test cannot handle. In this article I want to describe the different types of Android tests and how…

Draw circle sector in Android

Today I had program a heading indicator for a Android map-view (osmdroid). My idea was to use a circle sector (similar to most map applications). After some experiments, I came up with the following code. It uses a Path and basic trigonometric functions: private fun Canvas.drawCircleSector( x: Float, y:…

Resize LVM Volume after changing disk size of VM

Today I realized that the root partition of one of my server-VMs was completely full which caused errors in various different services running on this VM. My Goal was to resize the root partition without rebooting the VM (because it was running some production code). The first step was to…

DIY automated plant watering system

This spring I decided to grow herbs for cooking outside my kitchen window. However, as it turned out after a short time, regular watering is essential. After I got rid of the dried out (and/or drowned) plants, I decided to automate the watering process before trying again. Parts I…

Detect iPhone presence in Node-Red

Detecting the presence of an iOS device in the network can be challenging because iOS does not respond to ICMP ping messages. Fortunately, nmap can be used to check the host's availability. Command of the exec-node: nmap -sn 192.168.1.101 The function node is used to check if…

Positionsbestimmung mittels VOR und SDR

VORs (oder auch Drehfunkfeuer) sind Sendeanlagen, die jeweils ein rotierendes und ein ungerichtetes Signal aussenden. Anhand der Verschiebung zwischen beiden Signalen kann ein Flugzeug seine Aktuelle Position bestimmen (genauer gesagt die Richtung im Verhältnis zum VOR). Die genaue Funktionsweise ist hier sehr gut beschrieben: https://de.wikipedia.org/wiki/Drehfunkfeuer.…