Simple time lapse with ffmpeg
4 mins
Short summary on how to generate time lapse videos from webcams or other sources using ffmpeg on various platforms
Simple laser cutting and engraving capabilities for a 3D printer with a 450nm diode laser
27 mins
This article summarizes some experiments using a simple 450nm laser diode on a 3D printer for some basic laser cutting and engraving in paper, plywood and other simple to cut materials.
Why you should not use SMR disks for ZFS
12 mins
A short story about SMR disks in ZFS ZPools and why you should never ever use them there even when it looks ok on the first look and why you should replace them as fast as possible even when you don't see problems in the beginning.
Switched mode DC-DC converter basics
40 mins
A short summary of the basic principles behind switched mode DC-DC converters (buck, boost, buck-boost, etc.), maximum power point tracking and impedance matching as well as a short recapitulation of the charging and discharging of reactive elements such as inductors and capacitors.
A simple digitally controlled small current source
11 mins
Simple project that provides a digitally controllable linear current source up to 500 mA powered from a rectified 230V to 12V transformer. The whole current source is bias-able to high voltage (-2 kV in this case) by opto isolating it's serial communication path
Simple 230V monitoring using PC817 opto coupler
3 mins
A really simple circuit to monitor the presence of a 230V AC line using an PC817 opto coupler and a 5V or 3.3V microcontroller
Simple DHCP failover with ISC-DHCP
6 mins
Mini summary on how to configure DHCP failover or load balancing when using ISC-DHCP for legacy IP networks. This is not a full explanation of all details, just a quick sample on how to get up failover in a few minutes.
How to use fetchmail to collect mail from different mail servers
7 mins
This blog post tackles a common challenge in email service administration where users set up mail forwarding without implementing Sender Rewriting Scheme (SRS), which leads to problems with email authentication methods like DKIM and SPF. The suggested workaround is to reverse the forwarding process by configuring the receiving mail server to periodically fetch mail from external accounts using the `fetchmail` tool, which requires only the target server to be configured. Detailed steps explain how to configure `fetchmail` alongside a local MTA like Postfix to pull emails while bypassing SPF and DKIM checks for localhost deliveries. The author shares his personal experience using this setup during a mail service migration, emphasizing the advantages of the method while also discussing the security consideration that `fetchmail` needs access to plaintext credentials. The post includes comprehensive steps for installing and configuring `fetchmail` on a FreeBSD system, and configuring Postfix to ensure proper mail delivery without authentication checks for fetched mail.
Measuring the speed of light at Wiener Forschungsfest 2022
14 mins
This article allows you to discover how we (a group from TU Vienna and University of Vienna) brought the fascinating world of physics to life at the Wiener Forschungsfest 2022! Using a visible range laser, a bicycle wheel, and modern photodiodes, we demonstrated how to measure the speed of light in an interactive and engaging setup designed mainly for children. This hands-on experiment highlighted the incredible speed of light while also conveying the fact that light is fast but not infinitly fast and allowed visitors to influence the accuracy of the measurement themselves. This article provides a short summary about the historical context, experimental setup, and the exciting outcomes of this educational outreach project.
Temporal correlation in coherent cathodoluminescence
1 min
Presented at the 16th Multinational Congress on Microscopy (16 MCM)
