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As a hackerspace we regularly host user-groups and irregularly host talks and workshops and all of them need to use our beamer. Quite a downer then, that our beamer’s HDMI and DVI Input stopped working with newer laptop graphic cards. Especially since VGA started having it’s own issues: Dark slides transmitted over our long VGA cable cause the beamer to decide input has disappeared and switch the input off.

A look at the kernel messages with dmesg made the source of the problem immediately…

Read about Flocx’s current project, a battery-saving WIFI+MQTT-enabling cheap smoke-detector here: https://blog.flo.cx/2018/08/ikea-diy-smart-smoke-detector/

I wanted to do the same thing for my flat, but instead of using the IKEA one, I ordered two cheap 7€ SmartWares detectors from Amazon with 9V batteries that are advertised to give 5yrs battery life and otherwise identical hardware. Also instead of µPython I used Sming and C++. Just for the fun of it, I also added a voltage divider that…

Heute hatten wir einen kurzen Aha-und-WTF-Moment beim Basteln eines WIFI-fähigen Brandmelders (ESP8266 der im Alarmfall von der Brandmelderbatterie bootet und eine SMS schickt):

Wir versorgten den Melder mit einem Labornetzteil (9V) und maßen Signale mit dem Oszilloskop. Als wir den Prüfspitzen-GND mit GND der Schaltung verbanden… funkte es kurz! Wie kann dass denn sein?

Daher Multimeter her und mal durch messen! Mhhh, da liegen 9V zwischen dem Minuspol des Labornetzteils und dem Oszi-GND bzw…

The more complex a program or application, the more likely it contains exploitable or otherwise dangerous faults. Containers are a way of limiting the damage by limiting an application access to the bare minimum. Ideally we would have a separate and instantly replaceable computer for every little daemon and service we run. Sadly, even with virtual machines, this would hardly be an efficient use of resources, so containers try to find a middle ground by allowing us to separate applications…

At home, my Samsung laser-printer uses 15W during standby. So, a few years back, in order to save power, I put it on a USB-controlled power-plug. Pretty soon I added a tiny script that would query cups if a print-job was queued and would switch the printer on and afterwards off again. It turned out to be a pretty effective power saving measure.

Our two very big and reliable printers at realraum were even more power hungry, so I wanted to to something similar for the space.

Using the…

Years ago we got some horribly expensive foil needed to engrave metal using our laser-cutter. Today is, as far as I know, our first attempt to actually use it.

People always seem to search for a lighter, but then forget to put them back. As a result, even the safely stored ones can never be found when a Bunsen needs to be lit (which we actually have an Piezo for that the evil smokers don’t want to steal) or a flame is needed for some project.

Reason enough to make a big deal…