Encoder using Hall-Effect Switches
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How would I mount the Hall-Effect switch on my Boe-Bot to track rotations of the wheel?
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So many projects, so little time.
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So many projects, so little time.
Comments
But, a simpler ready-made solution that would have the same effect would be:
http://www.parallax.com/detail.asp?product_id=28107
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Chris Savage
Knight Designs
324 West Main Street
P.O. Box 97
Montour Falls, NY 14865
(607) 535-6777
Business Page:·· http://www.knightdesigns.com
Personal Page:··· http://www.lightlink.com/dream/chris
Designs Page:··· http://www.lightlink.com/dream/designs
·
a magnet?
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So many projects, so little time.
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So many projects, so little time.
http://www.parallax.com/detail.asp?product_id=602-00010
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Chris Savage
Knight Designs
324 West Main Street
P.O. Box 97
Montour Falls, NY 14865
(607) 535-6777
Business Page:·· http://www.knightdesigns.com
Personal Page:··· http://www.lightlink.com/dream/chris
Designs Page:··· http://www.lightlink.com/dream/designs
·
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Jon Williams
Applications Engineer, Parallax
Dallas, TX· USA
There are two main types of Hall effect switches.
One is latching and the other is not.
Be sure that you get the type you want (If I recall correctly, the non-latching is what you want) or you will find that you have to do some additional engineering to get operational.
Incidentally, Hall Effect switches are about the same prices as regular switchs and eliminate any and all bounce. This can be useful if you want to use them a on/off pressure or positon sensors in various parts of a robot. The only draw back is that they require +5 volts, but then again all de-bounce schemes require this much or more.
More magnets are only useful for reasonably slow rotation where you might want to exactly position a wheel (I think a stepper motor can do this better) or for sensing parts of a circle (such as a direction indicator for wind). In either case, you have the option to have more magnets on the spinning shaft (which may be hard to place) or more Hall-Effect sensors positioned around the outside.
It seems to me that more sensors is the way to go.
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G. Herzog in Taiwan
-products-sensors.
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So many projects, so little time.
I have been using latching hall effect sensors with small magnets for a similar task. The problem I have found is getting a strong-enough magnet to toggle the hall-effect with a 2-3mm range.
Need to see what the guass of the magnet and hall-effect sensor are to work this out...
James
Has practically any size you could want, and they are rare earth magnets, they'll trigger a hall effect from a fair distance. A large enough magnet held in your hand near a filing cabinet or fridge will break the bones in your hand! (like this one http://www.wondermagnets.com/cgi-bin/edatcat/WMSstore.pl?user_action=detail&catalogno=0072·thats 12,100 gauss multiplied by its surface area, more than enough·to yank the jumperwires right off your bot·
·Paul
Post Edited (Paul Baker) : 2/3/2005 8:18:38 PM GMT
your magnets (if more than one make sure they are spaced evenly). The magnet will need to pass in close proximity to the sensor for it work so check that alignment
prior to making the attachmnet premanent. Also watch out and make sure that the magnets don't interfear with the normal rotation of the wheel. For the sensor
pay attention to its orientation (see your application notes).