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Photointerruptor Identification Help... :( — Parallax Forums

Photointerruptor Identification Help... :(

FlyingFishFingerFlyingFishFinger Posts: 461
edited 2009-12-19 07:28 in General Discussion
Hi-
I've got a photointerruptor labelled K-2212, 5301-01 and 8301. Inside are identical-looking LED packages, one clear, one smoky gray. Which one's which? I can't seem to find a datasheet for this...anyone have any ideas?
Thanks

Raf

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UC Berkeley '12 EECS
CalSol: Berkeley Solar Car team
www.calsol.berkeley.edu
KJ6AWU

Comments

  • kwinnkwinn Posts: 8,697
    edited 2009-12-19 02:08
    I am assuming since you say "identical-looking LED packages" they both have 2 leads. If one had 3 leads it would be the transistor. You could connect both to 5V through 1K resistors and measure the voltages with the slot open and blocked. Reverse connections and repeat. That should give you enough info to figure out which is which.
  • FlyingFishFingerFlyingFishFinger Posts: 461
    edited 2009-12-19 02:13
    If I get the direction wrong, that won't blow it up? Ok I'll try that

    Raf

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    UC Berkeley '12 EECS
    CalSol: Berkeley Solar Car team
    www.calsol.berkeley.edu
    KJ6AWU
  • FlyingFishFingerFlyingFishFinger Posts: 461
    edited 2009-12-19 03:14
    Okay, I can't make head or tail out of this.
    Out of all the 8 possibilities (which one being measured, polarity of each) only one comes close to making any sense. In this position, when it's interrupted, my Prop reports consistent "LOW", when it's not, it alternates between low and high about every half a second. In any other setup but two, the same pulsing happens independent of the position of the sensor. The last two setups always remain high. What do I have here??

    Raf

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    UC Berkeley '12 EECS
    CalSol: Berkeley Solar Car team
    www.calsol.berkeley.edu
    KJ6AWU
  • FlyingFishFingerFlyingFishFinger Posts: 461
    edited 2009-12-19 05:17
    Got it to work, thanks [noparse]:)[/noparse]

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    UC Berkeley '12 EECS
    CalSol: Berkeley Solar Car team
    www.calsol.berkeley.edu
    KJ6AWU
  • FranklinFranklin Posts: 4,747
    edited 2009-12-19 05:51
    Could you let us all know what you found? It will help others.

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    - Stephen
  • FlyingFishFingerFlyingFishFinger Posts: 461
    edited 2009-12-19 07:28
    Of course. Turns out that it was actually an IR led. I used the diode test setting on my multimeter to determine which was which (the detector showed no voltage drop connected either way whereas the LED did connected in one direction - this also gave me the correct polarity for it). I also needed to use a lower resistance to drive the LED. 470Ohms works well.
    The Prop can directly read the detector as a digital input. It's connected to 3.3V through about 5k which gives about 2V when the sensor is not interrupted and 0V when it is.
    Works great[noparse]:)[/noparse] Now to find out how fast of things I can actually measure...

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    UC Berkeley '12 EECS
    CalSol: Berkeley Solar Car team
    www.calsol.berkeley.edu
    KJ6AWU
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