May 132012
 

20120513-235231.jpg

I wanted to be able to locate wifi signals, so I built a directional antenna and strapped it onto my panorama robot. The waveguide style antenna built from a used can (explains the name cantenna) looked to be the easiest to build. I bought a pigtail with an N male connector to RP-SMA male connector.  I plugged this into my Alfa Network AWUS036NH. I then fired up inSSIDer and used PuTTY to control the Arduino sketch and aim the antenna.

The signal strength was not what I expected to see at all. I assumed this antenna was directional and would be strongest when I pointed it directly at the AP. It was strongest pointing at about a 45 degree angle to the left of the access point. I’m a complete n00b when it comes to RF, so any feedback on why I’m not seeing what i expected for results would be greatly appreciated.

Note: Will update post if/when I have an answer.

Update:

I am a complete n00b when it comes to build antennas. I goobered another can on there and it works a lot better. I have to give a great thanks to several redditors for pointing me in the right direction. I’m always impressed with how helpful people are. http://www.reddit.com/r/electronics/comments/tmtbi/attempting_wifi_direction_finding_with_a_cantenna/ Even better, I’ve got some reading to do now.

I’ve included links I found useful or interesting and more pictures.

Continue reading »

Apr 292012
 

I’ve kept a list of links I found very helpful lately. While I’m no stranger to a soldering iron and I know how to use perfboard, I have never etched a PCB before and I’ve never designed a PCB. I don’t think I would have had much luck at all without the following sites. I still use them quite regularly.

http://www.adafruit.com/tutorials

http://www.sparkfun.com/tutorials/category/1

http://arduino.cc/en/Tutorial/HomePage

http://tronixstuff.wordpress.com/tutorials/

http://www.ladyada.net/library/procure/partsdistributors.html

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Apr 112012
 

Laser pointer turret, x y coordinate laser pointer, overgrown cat toy, whatever you want to call it. It has been done before 1001 times over, but I wanted to do it again, for myself. The hardware part of this is extremely simple. I just switched the device from the cat annoyance post from solderless breadboard to perfboard and headers. The X axis servo is on pin 9 and Y axis servo is on pin 10. I broke the Aixiz laser module I had on there, so I replaced it with a cheapo laser pointer from wal-mart.

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http://www.ragingcomputer.com/2011/11/cat-annoyance

I didn’t care for the code I had written before. It just moved the laser from one point to another random point. The cats seemed more confused by its erratic behavior than amused. I figured circles would be a good idea. I swiped snippets of code and inspiration from the following forum post.

http://arduino.cc/forum/index.php?topic=97984.0

I want it to turn off after 15 minutes, and reset after an hour. To add some variability, the diameter of the circle increases and decreases, the speed is random, the circle point of the circle is random too (all within certain limits).

I’ve included the code below
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Feb 192012
 

The menu for the panorama robot is slowly getting more useful as I learn how to make the menu structure. Once I figure out saving values between power cycles, I’ll be ready to mount the 16×2 LCD screen.

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Of course I can’t show the video without also showing the result (scaled to 50% to keep filesizes manageable).

Feb 072012
 

I have mentioned panoramas before. This time, it got lazy. I’m sure things will improve, since this is the first run.

It uses a lazy susan bearing, 2 Futaba S3004 servos, a Hitec HS-55 micro servo, an Arduino UNO SMD, a pile of brackets, bolts, boards and wires. I whipped up an arduino sketch that starts the panorama when I hit the letter “a” in a serial terminal, prints the servo angles for each stop, then waits for input when it’s done. I’ve decided on a 10 degree step in both pan and tilt with the zoom in all the way on the Nikon S220 camera. To get the pictures to my laptop, I use my Eye-Fi Share 2GB SD card. I then use Microsoft Image Composite Editor to stitch them.

And here’s the result, scaled down to a reasonable size. There are definitely some stitching errors. I suspect having the camera angle skewed to the right doesn’t help much.

Nov 032011
 

I got an Arduino Uno for Christmas last year, and of course the first thing I think of is laser pointer turret. I played with this for months while I learned the basics of Arduino programming. It was knocked apart when hail totaled my Trailblazer.

To simplify rebuilding the turret, I bought a pan/tilt kit from trossen robotics. I upgraded the laser from a wal-mart cheapo with the buttons taped. Aixiz lasers are inexpensive and very easy to use. The aluminum mount is taped to the pan tilt kit.

http://www.trossenrobotics.com/store/p/3139-Pan-and-Tilt-Kit-with-Servos.aspx

650nm 5mW laser module.3.2V 12x30mm
http://www.aixiz.com/store/product_info.php/cPath/59/products_id/302

12X30mm aluminum mount for AixiZ 12X30mm units
http://www.aixiz.com/store/product_info.php/cPath/28/products_id/99

I actually bought my laser parts through eBay
http://stores.ebay.com/aixizserviceandinternationalllc

The arduino and radio shack project boards are housed in a plastic bin I bought from wal-mart for a couple bucks. I hung it on the wall with a piece of decorative ribbon swiped from my girlfriend’s wrapping bin. I wanted to see the cats attacking the laser, so I dug out my webcam.

 

Hanging from the wall in place of a picture. Continue reading »