Jeff's Blog

My daily (well I am trying to update daily now) weblog covering topics such as wind power, embedded electronics, software development, CNC Machines and some fun stuff like travel and sailing.

Friday, January 30, 2009

Gear-Wheel Designer Vastly Improved

When I wanted to couple my prototype Savonius wind turbine to an off-the-shelf alternator, I decided to use gears. I cut the gears on my IMService CNC machine using an inexpensive piece of software from Delph Electronics called the Gear-Wheel Designer

Graham Baxter's Gear-Wheel Designer with G-code generator lets you type in a few parameters, press a button, and get a DXF file of a gear, along with G-code to run a CNC machine. This program allowed me to make gears to electrify my wind turbine without being an expert on gear cutting. Click here to see a video of the wind turbine in action.


The user interface of the Gear-Wheel Designer is quite simple and contains a parameter area and a graphical preview of the gear to be rendered:



Here is a picture of a gear produced from the software.




The latest release has the ability to create five gear types as opposed to just cycloidal and involute gears in the previous release. The new release added the capability to design ratchet wheels, dead-beat ratchet wheels and anchor ratchet wheels. See this page for more detail on the new gear/wheel types. Also added was the ability to create wheels with spokes as shown above. There are also a number of other new features as this release was a complete rewrite of the software. They let you download the user manual prior to purchase so I advise doing this to find out more details about the software prior to purchase. This software does not attempt to teach you terminology or gear design concepts so if you are like me and don't know much about gears, you should do some research prior to machining your gears.

This software is definitely a bargain at less than $80 to purchase. I just upgraded to the latest version and will be trying it out on my next generation vertical wind turbine. I am also going to try my hand at machining a pendulum clock. Watch this blog for future updates if interested in gears.

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Tuesday, January 13, 2009

Canon A590 IS + Eye-Fi Card + CHDK open source software = FUN

A friend of mine owns a liquor store and was robbed recently of some high priced bourbon. He had a professionally installed security camera system which recorded the thief's car leaving the parking lot. Unfortunately, the detail of the NTSC video output was insufficient to recognize the license plate number, hampering the investigation by the police.


I wondered why the resolution in pixels in security cameras hasn't improved much since the 1950's. I researched some newer, higher definition, security cameras, and found a very nice one:


The Sony EVI-HD1





"The Sony EVI-HD1 is a color motorized PTZ camera that can be switched from displaying standard NTSC/PAL resolution video to outputting high definition images with a maximum resolution of 1080i. By starting off with such outstanding video quality, images will retain their sharpness and color depth even under extreme digital magnification."




This is a very nice piece of equipment. Unfortunately, it costs over four thousand dollars. Because of the price, this was not a cost effective purchase for a small liquor store.


I began to look around and found out about the EYE-FI card, a secure digital card with 2GB of storage combined with a limited Wi-fi capability. I already new about CHDK, an open source software project which allows one to "take over" the firmware of certain models of Canon digital cameras. I researched work done by the many programmer volunteers who contribute to CHDK, and came up with a solution which combines a Canon A590 IS inexpensive point and shoot camera, an Eye-Fi Card, and CHDK open source software to produce a "poor man's" high definition security camera. Total hardware outlay for the development prototype was less than $300. Now, because of sales on the camera and chip, this number can drop to under $200. While it does not have remote pan and zoom capability, it does have very high 8 Megapixel resolution, which may preclude the need to pan and tilt by instead using an optional wide angle lens to cover a large area of a parking lot. Also, being more inexpensive than the alternative would allow the deployment of multiple DIY cams for the price of a single high end camera.

I wrote a script to run under the CHDK firmware which detects motion, snaps a picture, uses the eye-fi card to send the picture to a PC or photo sharing site over my home wi-fi network, and then automatically delete old images on the eye-fi card so the card does not run out of space (this should be built into the eye-fi card but is not). I used a language called LUA, used to write advanced scripts under CHDK, and eventually got the camera to successfully upload eight gigabyte images in real time. Here are some images I was able to capture in my front yard while pointing the camera at a bird feeder (you can click on the images to see them at 1600 x 1200, the actual images out of the camera are at 3264 x 2448 pixels which is too big for my blogging software to upload):











This week I will be stress testing this solution. Others working with the eye-fi card in similar endeavors on the CHDK wiki report that they are having reliability problems with the eye-fi card after 18 hours of constant use. They are attacking the problem by using an embedded computer to reboot the camera by simulating depression of the power switch. I am going to see how long I can run this system without a lockup before attempting to make any hardware modifications of my own. Obviously, to be used a security camera, the system must be reliable. I am not putting this into the liquor store until it has run at least a month in my house without failure. I will keep you abreast of the project as it progresses. My final script will be published on the CHDK forum. I am going to get back on wind turbines and RF remotes later this week.



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