Monthly Archives: July 2011

Haard & Dortmund-Ems-Kanal


Vergrößern

Endlich mal eine Pause vom Dauerregen und mal wieder Zeit (knapp 3 Stunden) für eine 69km-Tour 🙂 Dabei ging es auf direkten Wege in die Haard, kurz durch und dann am Wesel-Datteln-Kanal nach Datteln und von dort aus am Dortmund-Ems-Kanal entlang in Richtung Zuhause.

Außerdem war es eine gute Gelegenheit, mein mobiles USB-Ladegerät auszuprobieren, dass auch tatsächlich die Ladung über 2 Stunden lang auf 100% gehalten hat.

Building a mobile USB cell phone charger

Using your smartphone as a GPS tracker when biking tends to drain the battery very fast. For long tours this might actually be too fast. So I decided to build a mobile cell phone charger that runs on two standard AA batteries and extends the run-time of my smartphone. (To be honest before deciding to build my own I bought a commercially available one which unfortunately went up in smoke. Fortunately Amazon has a nice return policy and after once more killing the same model again I got my money back).

I’ve previously experimented with the LT1073 converter which is nice because it can provide 5V out of a single cell. However, this time a bit more power was needed and so I got hold of a LT1302 which is able to produce 5V at 600mA from a 2 cell supply.
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Writing the first Android App: Guess-the-Number Game

Having installed the Android SDK and getting to work the Hello-World-Sample, it’s time to write the first app that isn’t just written down from some tutorial website.

I chose a simple number guessing game, as it was the first piece of code I can remember to have written ever. It was part of the users manual of the Commodore 64 my brother bought back in the time when 8 bits ruled the world 🙂

Screenshot of the finished number guessing game

The reader of this mini tutorial should be familiar with Java and at least the “Hello, World” tutorial I refered to in an earlier post.

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Installing the Android SDK on Windows and saying Hello to the Android world

Having owned an Android device for more than a year I never found the time (and motivation) to start developing for the Android plattform. With holidays ahead I thought I finally might find the time and with some ideas in the head motivation wasn’t far. So here are my experiences of installing the Android SDK and getting to run the traditional “Hello World” application:
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Calculating an intercept course to a target with constant direction and velocity (in a 2-dimensional plane)

For some game idea I worked on a bit some time ago I needed a bit of maths. Luckily all that was needed was taught at school and with a bit of thinking (and trying) it all worked out:
diagram of a moving object to be intercepted by a projectile

Let’s consider an object at point A moving with the constant speed vector \vec{v}. At point B we got the ability to fire a projectile with speed s. Where do we have to aim at to hit the object with our projectile? In other words: what is the location of point I or what would be the vector \vec{x}?

Now let us derive the necessary maths and put it into code… (requires understanding of vectors and quadratic equations)

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Vollmond

Taken with a Canon 550D and the Canon EF-S 55-250mm (standard kit) lens (F9, 1/30s). Adapted brightness levels and sharpened in post-processing.

Aufgenommen mit einer Canon 550D und der Canon EF-S 55-250mm (Standard Kit) Linse (F9, 1/30s). Helligkeit und Schärfe in der Nachbearbeitung angepasst.

Extraschicht 2011

Do it yourself cable remote for Canon Digital Rebel cameras

If you got tons of electronics spare parts lying around (like me) you can save money (and have fun) by building your own cable remote.
The wiring is quite easy. The sleeve connector of a 2.5mm (3/32 inch) stereo audio plug serves as a ground terminal for the focussing (ring connector) and release (tip). Just attach buttons and you’re done. For better usability, e.g. a cable extension, I connected the 2.5mm connector to a 3.5mm connector which will be plugged into the remote.
Wiring of a Canon Digital Rebel cable remote
The final cable remote
And yes, the last picture was taken using the remote you see.

Attention: Some (weird) people might mistake the clearly unostentatious, mildly geeky nature of the design for some different kind of trigger…