Subject:
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Re: Another DIY sensor
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 16 Nov 2000 17:56:32 GMT
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Viewed:
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1481 times
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John Barnes wrote:
> My continuing journey into the world of DIY RCX sensors
> has lead me to a home made rotation sensor which may be
> of interest.
>
> Since the RCX light sensor reports values in the range 0 - 100
> and my compass sensors are thus constrained to report 0 - 360
> as a scaled value in the range 0 - 100, I have settled on a new
> scheme in which there are 100 RCX degrees in a circle. Actually
> not a bad system of measurement when you get used to it.
>
> Needing to rotate detection sensors with a matching resolution, I
> initially used the standard Lego rotation sensor, but it needs
> considerable gearing to get up to 100 counts per rev. and suffers
> the inevitable backlash problems. So I decided to investigate DIY
> rotation sensors. The first two or three simply didn't work. Then
> I hit upon the magic recipe;
>
> I made a slotted disk using overhead transparency material in the
> laser printer. A simpe disk with 25 black segments.
>
> Then I found that digikey sell an Omron dual optical interrupter
> module.
>
> The transparent disk is glued on a piece of modified Lego which
> fits a cross axle. (I used a small propellor with the blades carefully
> removed). I built the thing up sandwiched between a couple of
> technic style plates with an RCX interface consisting of the usual
> 6 diode and capacitor interface. The two outputs from the interrupter
> go through a LM393 dual comparator and are summed with 6.8k
> and 15k resistors to the RCX giving almost exactly the same
> voltages as I measured from a real rotation sensor.
>
> The 25 black slots give the required 100 counts per rev! It works
> great.
>
> If anyone needs any more detail, please let me know. I will try to
> take a few pics this weekend.
>
> JB
Use RAW mode. Then you get 2500 to 0 (I think it was)
Dean
--
Coin-Op's For Sale!: http://www.akasa.bc.ca/tfm/coin-op.html
Dean's Lego Workshop: http://www.akasa.bc.ca/tfm/lego_wr.html
Vancouver Lego Club: http://www.akasa.bc.ca/vlc
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Message is in Reply To:
 | | Another DIY sensor
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| My continuing journey into the world of DIY RCX sensors has lead me to a home made rotation sensor which may be of interest. Since the RCX light sensor reports values in the range 0 - 100 and my compass sensors are thus constrained to report 0 - 360 (...) (26 years ago, 16-Nov-00, to lugnet.robotics)
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