I found myself firing up a calculator every time I needed to base-convert a number from/to hex or octal. So I wrote a very simple HTML-page that I added to my dashboard that does just this.
Just found this wonderful site which matches your drawing to the corresponding Unicode character(s).
FreeBSD is, by default, still limited to usernames of less than 16 characters. Changing this to 32 or even 64 is not difficult, but does require some time to recompile the entire system.
I often find myself changing routes on my OS X system. Usually, however, I’m systematically adding the same routes over and over again, because they were automatically removed after a reboot, network change or whatever. Enter LocationChanger.
Continue reading ‘Automatically doing things when you change network’ »
ZSH has some pretty nifty TAB-completion. But I found the git completion to be slow, especially on large repo’s. I wasn’t the only one. Some suggest to disable the context-aware completion completely, but I prefer Victor Quinn’s pointer to this solution which just upgrades the completion logic to the latest version. Continue reading ‘ZSH git completion slow’ »
I was a bit afraid that getting an UMTS USB stick to work under Linux would be an impossible task. Turns out to be reasonably simple. These notes are for a Huawei K4505 HSPA+ USB stick, as provided by Proximus (Vodaphone group).
As already introduced in a previous post, OpenPGP keys have different uses. These uses are: certify other keys, sign data, encrypt communications or storage and authentication. To maximize security, I already have a master key which I only use to certify other keys, but the key flags don’t enforce this.
I was very excited to get our new heating system which uses the OpenTherm protocol to communicate between the boiler and the thermostat. I found the electronic schematics, including PCB design and PIC firmware to make an OpenTherm gateway. This would allow me to plot the different temperatures and modes and learn from the statistics to fine-tune the heating! Only to find out that my, newer, version of the boiler doesn’t use OpenTherm anymore, but uses another type of bus… Back to square one. Here is my journey to reverse-engineer the protocol.
Continue reading ‘Reverse engineering the Elco heating protocol’ »
I needed an oscilloscope that is able to record minutes of signal and export that data to a computer. An oscilloscope is, in fact, nothing more than a analogue-to-digital convertor that samples the input signal fast enough. Exactly what a sound card’s recorder does!
The line-in of my MacBook Pro (6,2) has an input impedance of 28kΩ, and is AC-coupled. So it’s not possible to measure DC voltages. The DC-decoupling capacitor has a 30ms half-time (τ=43.3ms), which makes it capable of measuring down to 3.6 Hz (@-3dB).
Test measurements have shown that 350mV results in 0.115 full-scale deflection, yielding an approximate full-scale voltage of 3V (i.e. ~2.1Vrms).
The setup
The signal that I wanted to measure was 12Vdc, with pulses down to 0V. Putting a 330kΩ resistor in series with the input resulted in a voltage division of ~12.7, bringing the 12V safely below 1V and limiting the maximum current draw to 33µA.
Apparently, by default, Windows Server 2008R2 doesn’t accept Ctrl-Alt-Del keystrokes from the UltraVNC service. This website provided the solution:
- “Start menu” -> “Run…” – > gpedit.msc
- Navigate to “Computer Configuration” -> “Administrative Templates” -> “Windows Components” -> “Windows Logon Options”
- Double-click on the “Disable or enable software Secure Attention Sequence” parameter.
- Check “Enable”, then select “Services” in the combobox.
- Apply the modification
