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  • Category Archives wetenschap/science
  • Old Android phone = cheap IP cam

    Posted on August 12, 2012 10:22 pm by Johan

    So, I got me a new Samsung phone because my old phone, a HTC Wildfire is rather slow, especially when it comes to websurfing. It also has low crap resolution. I am much happier with the new phone. So, what to do with the old phone? It’s still a small computer with a camera and touchscreen that should be doing something instead of gathering dust in a drawer.

    One of the things I thought of was a webcam for my turtle tank. It currently houses two (I think female) red cheeked mud turtles, kinosternon cruentatum. I wanted to observe how often one of turtles gets out of the water to bask and what the general activity in the tank is.

    I rooted the phone since I thought it would be handy to have root anyway and installed Cyanogenmod V7, an alternative Android version. This custom ROM does not include the Google Play store to install stuff on Google Play so I had to manually flash it. I am quite unexperienced rooting Android phones and installing custom software but I got it working eventually.

    Next I installed IP Webcam, a nice free webcam app. Since it has a webinterface for remote access it is easily accessible with any computer. Being http-based it’s very easy to grab the images over the wireless LAN that the phone is on using a bash script:

    #!/bin/sh
    wget http://192.168.64.4:8080/shot.jpg
    FILEDATE=$(date)
    montage -geometry +0+0 -background white -label "$FILEDATE" ~/shot.jpg /var/www/meuk/schildpadcam.jpg
    mv ~/shot.jpg /storage/plaatjesenfotoos/schildpadcam_arch/"$(date +%d%m%y%H%M)".jpg

    This script uses wget to fetch the most recent video frame (the app is capturing video all the time), uses the imagemagick tool montage to visually timestamp the image and outputs a new picture in a publicly accessible folder on my server. Finally, the most recently downloaded picture is renamed with a timestamp in the filename and moved to a archive directory on the server. Continue reading → Post ID 1088


    Electronica english wetenschap/science 📎and tagged android bash cyanogenmod Electronica htc ip cam linux timelapse youtube
  • Fukushima radiation myths

    Posted on August 6, 2012 12:34 am by Johan

    On the Internet there is lots of misinformation and people willing to promote ideas that have little base in reality.  After the Fukushima disaster, thousands of people around the world feared that the released radioactive materials might reach his/her country. Especially in the US, lots of people have access to radiation measurement equipment. For example, the Civil Defense program during the cold war caused a big amount of surplus geiger counters and survey meters to be available at little cost.

    Soon after the disaster, people started measuring and found that after rainfall background radiation can increase quite dramatically and swipes of rain-covered cars/roofs/windows can cause a geiger counter to crackle quite loudly.

    The cause of this radiation is Radon. Radon emanates from uranium present in the soil of most areas on earth. This radioactive gas decays to short lived nuclides like Polonium-218, Lead-214, Bismuth-214 as shown in this picture from Wikipedia:

    Continue reading → Post ID 1088


    skeptisch/sceptical wetenschap/science 📎and tagged cesium conspiracy fallout fearmongering fud fukushima myths physics potrblog radon radon washout rain sceptic radiation radioactivity
  • Some rad links…

    Posted on August 1, 2012 7:44 pm by Johan

    Below are some interesting links about radiation (detection) that I have collected over time:

    Have questions about geiger counters, the CDV-700 or gammaspectrometry? Just go to these Yahoo groups:

    CDV700CLUB : The CDV 700 Club is a forum for like minded individuals that enjoy collecting, fixing up, and using geiger counters and other r

    GeigerCounterEnthusiasts : PAGE 2…for Archives go to PAGE1

    GammaSpectrometry : Gamma Spectrometry

    Want videos? Check out these awesome Youtube channels:

    http://www.youtube.com/user/antiprotons?feature=watch

    http://www.youtube.com/user/antiprotons?feature=watch

    Want pictures? Check out the Flickr Radioactivity pool: Continue reading → Post ID 1088


    Electronica english wetenschap/science 📎and tagged Electronica english geiger counter radioactiviteit radioactivity
  • New geiger counter build

    Posted on July 7, 2012 7:56 pm by Johan

    I’m currently building a GM counter for a friend and was looking for nice, low
    power circuits working on 9V cells.

    I found this circuit which is derivative of Charles Wenzel’s designs:

    http://www.mikrocontroller.net/attachment/103170/Geiger_Hochspannung.png

    Components are fairly basic apart from the HV transistor and zeners. The other
    transistors can be basically any small signal PNP/NPN transistor from the
    junkbox. I used BC547 and BC557 and a MPSA44 HV transistor. Continue reading → Post ID 1088


    Electronica english wetenschap/science 📎and tagged Electronica english geiger counter high voltage radioactivity soldering
  • Some info on getting started with radiation detection

    Posted on May 23, 2012 2:06 pm by Johan

    Glass window GM tube

    Quite a lot of the posts on this weblog are about radiation. To summarize some of the information I decided to write this post.

    Geiger Counters

    If you want to detect some radiation it is the easiest to buy a simple geiger counter.  On eBay various geiger counters are sold for varying prices. Also check out the links at the end of the article. Possible options are: Continue reading → Post ID 1088


    Electronica english wetenschap/science

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