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$4 Digital IR Reflectance Sensor — Parallax Forums

$4 Digital IR Reflectance Sensor

ercoerco Posts: 20,256
edited 2012-07-20 10:16 in Accessories
Onboard adjustable comparator lets you set digital trigger threshhold, so this tastes very different than the analog QTI sensor. :)

http://www.ebay.com/itm/Infrared-sensor-switch-module-Smart-Car-Accessories-/170760140210?pt=LH_DefaultDomain_0&hash=item27c218f5b2

More info at http://www.lctech-inc.com/Hardware/Detail.aspx?id=725bda92-6df2-48c6-8b98-e9b4e653d4c7

Comments

  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-07-19 10:24
    I wonder how tall that trim pot is?

    One nice thing about those QTI sensors is you can fit them in relatively crapped places.

    I added this QTI sensor to read an encoder disk I added to a gear of a Roboni-I robot (which drives very nicely since being upgraded with a Prop).

    attachment.php?attachmentid=94288&d=1342718456

    I don't think the encoder you linked to would have fit in the available space.

    I can see having an adjustable threshold would be nice if you had the room for such a large sensor. They might make sense to use with a line follower since you could adjust for different brightness of stripes (as the S2 can do with software).
    RoboniIEncoder120719a.jpg
    475 x 524 - 124K
  • PublisonPublison Posts: 12,366
    edited 2012-07-19 10:52
    Really? Smart Car?

    Infrared sensor switch module Smart Car Accessories

    http://www.smartusa.com/
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2012-07-19 12:39
    Duane, Nice sensor, but it's not a QTI. The QTI is a Parallax product that uses a cap and resistor and measures intensity using RC. Yours looks more like the kind SparkFun sells (they use the "QRE" prefix from the Honeywell/Fairchild part they're derived from). My preference is the analog version, fed to a Schmitt trigger. For single channel odometry, a non-windowed comparator can be hellish if the darn wheel stops right at the threshold. The sensor Erco posted doesn't seem to show a schematic, so I'm not sure how its comparator is wired up.

    -- Gordon
  • ercoerco Posts: 20,256
    edited 2012-07-19 14:11
    Oh, what sad times are these when I can't find my lovely, tiny, discontinued Hamamatsu P5587 sensors. Built-in amp & filter, digital output. I bought several from Junun many moons ago. Why didn't I hoard those? http://www.junun.org/MarkIII/Info.jsp?item=48

    @Gordon: no schematic listed, but it does spec an LM393 comparator. Hopefully there's a high-value feedback resistor for some hysteresis.

    I bought a pile of these cheapie sensors (10 for $2), which are just an IR LED and PTX for use on processors with built-in Schmitt triggers: http://www.ebay.com/itm/290725756275 They're not tiny.

    What ARE tiny and quite sensitive (also just an LED & ptx) are these $1 units from Goldmine: http://www.goldmine-elec-products.com/prodinfo.asp?number=G18740

    You'll be hearing more from me about these parts soon. I have a long queue of neat EBay parts & sensors to test. MP3 modules; PIR, IR & flame sensors, etc. So many treasures, so little time!
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2012-07-20 10:16
    erco wrote: »
    @Gordon: no schematic listed, but it does spec an LM393 comparator. Hopefully there's a high-value feedback resistor for some hysteresis.

    With all those extra parts, including the precision pot (which is not needed, but it's nice to see they care!) it probably has something, but it's interesting they don't provide a schematic. Maybe they're afraid someone will steal their idea! :lol:

    -- Gordon
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