7 Jul 2005 cschur   » (Master)

Ive got some great projects going on to report. First, as an industrial robotics engineer, I am exposed to many components that have good potential in the home robotics arena. One part, Ive been using a lot of lately is the L298 motor H bridge driver IC. If you havent looked at this one, you should - its very cheap, has a high current capacity especially when used with a heat sink, and is easy to use. There are a few issues with this part, that make it a bit difficult to implement. First, the wierd pin layout can be easily over come by bending the outer row of pins to line up on the standard .1 centers to make two neat rows. Also, there are 8 external clamping diodes to consider. These keep the inductive kick from a stopping motor from getting back into your L298 and hence into your uP and poping it. While you can use a 1N4000 series diode for low current motors, you really need to use a shottkey fast recovery diode for the larger motors. THese are cheap too, and you can order both L298 and Shottkey diodes at Digikey or Jameco for like 4 bucks:

http://rocky.digikey.com/scripts/ProductInfo.dll? Site=US&V=497&M=L298N

Another neat thing to get you going on your next robotic project is the new Dirt Devil electric sweeper. This is one of those push sweepers with the rolling brush inside for medium duty cleanups in the house and industry. But this one, is VERY cool, in that it is electric/rechargeable and should be relatively easy to make robotic. I couldnt resist so bought one from Walmart for under $30. It is actually an amazing floor and carpet vac! Super cleans. It comes with a charger, and a 7.2v internal battery. I ran mine on a ful charge to see how long it would go - 3.5 hours! Now that will scrub those floors to a polish, and keep that shag rug spotless. I am going to add a dual wheel drive, and some bumpers to get it going. Youve got to get one of these things, they beg to be made into a robot. This is an add for the more expensive model, they dont have one yet for the new under $30 one yet:

http://www.dirtdevil.com/sweeper/

Finally, last night I got our new robotic digital sky camera in operation. Youve seen my robotic film camera and barn door type mount. This new one operates the hand held remote by pushing the button with a mechanical linkage and timing the bulb exposures, operating the star tracker for all night unattended sky shooting. Remember, a robot doesnt have to have wheels to be a robot! This one takes the hard labor out of haveing to sit there all night long and manually click the cameras shutter, rewind the tracker and time exposures. More on that and some great images I got last night with this setup are comming...

Later,

Chris

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