New personal blog

After blogging here since 2007, I finally moved to a new domain.

Find the new personal blog on alexanderhupfer.com

Popular posts from this blog

Dry-Ice Canon fun

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Use frozen carbon dioxide (dry ice), mix it with water and pipe the steam into a PET bottle. When the bottle at roughly 22bar explodes you can shoot for example a toy chicken over more than 80 meters (We had serious problems to build a projectile that is not destroyed by the power of the launch). We built the device for a creativity competition at our university. And well, we could not place an object accurate on 20m but for shure we did it with the biggest impact. Music on Amazon and iTunes If you are curious, here some detail about the construction: For us secure handling was not only an option. We have seen some people that put water and dry-ice together into an bottle close it and put it into a pipe. But you have good chances that it will explode in your hands. So we put an PET bottle into our pipe and connect it with an CNC made adapter to the presure reservoir outside. Beside that, all parts are made from steel and welded. We experienced that a 1.5l coke bottle (actually we used...
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OpenDNS Fritzbox Howto

While I did some research on how getting this to work I saw many people trying this without success. Here is the definitive guide on how you use OpenDNS with your Fritzbox: Make sure your firmware is up-to-date Enable telnet Login over telnet and type "cd /var/flash/", "nvi ar7.cfg" Search for overwritedns1 and overwritedns2 (they appear two times each) using the "/" key and "n" (next search result). Press "i" to get into edit mode and enter the opendns server as noted in the opendns linux guide ESC brings you back to command mode. ":w" saves the file and ":q" closes the editor again. type "reboot" to restart the fritzbox Restart you networking and you browser. The OpenDNS Site now should tell you that you are using OpenDNS already. Now you can create an account, set it to dynamic DNS, add network and login to dnsomatic. Now login to fritz.box using your browser and enter the following dynamic DNS settings...
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Setting up a Raspberry Pi for OSX using a direct ethernet connection

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The Raspberry Pi is a great piece of hardware. However you don't always want to hook it up to some screen and keyboard when working with it. I in fact never did since I like to do everything using SSH which is enable out of the box if you are using the raspbian distribution. So just hook it up to your router and start hacking. But what if you have no router and only you Mac? The Raspberry Pi is configured by default to receive an IP address from a DHCP server. So you need a DHCP server. This can be done using the sharing option in OSX. Just set it up like that, ignore the warning about your ISP, since you are not connecting to anything but you Raspberry Pi. You can also share your wifi-connection if you are at home but if you have secure enterprise wifi this option doesn't work. Once you have enabled this option just connect your mac and Raspberry Pi using an ethernet cable and THEN connect the power to the Pi. Also note that you don't need a cross-over cable, ...
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