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hi fellow hobbyists.. ?about sensors

Discussion in 'Sensors and Actuators' started by elioacm, Dec 3, 2018.

  1. elioacm

    elioacm

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    Jul 7, 2013
    so i have been doing some researching about proximity sensors using IR reciever and emitter and going to buy the materials today.;

    do you guys can recommend me a thread here or a basic components materials needed

    for an example; lighting up an LED by which it will light when certain object has entered the proximity.
     
  2. kellys_eye

    kellys_eye

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    Whilst doing this with discrete components is laudable I'd recommend you purchase a cheap'n'cheerful PIR sensor. These commonly use the BISS1000 chip and include all the parts you need at a price far below that of obtaining them individually.

    Google PIR Sensor Schematic on Google to see a gazillion schematics using such devices as the ubiquitous NE555 etc.
     
  3. elioacm

    elioacm

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    Jul 7, 2013
    but i want to make it from scratch, i just bought the materials needed yesterday and hope i can find out proper way to connect some of it on the board.. i have lm358 and some ir sensors i dont know if its correct for what am i trying to do.. its a blue and white one. i just gave the materials i need to the shop lady.
     
  4. Externet

    Externet

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    Obtaining the linked items, you can dismantle it to individual pieces, trace its schematic, learn/study how it works and put it all together again as you will have all the correct components, quantity-one and tested to work with no ordering wait, including the hardest to find, a proper housing, at an unbeatable price.
    Or, order the components found in it, and make another.
     
  5. CircuitMaster

    CircuitMaster

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    Dec 17, 2016
  6. elioacm

    elioacm

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    Jul 7, 2013
    ill get in touch been doing what all of you said.. ordered some parts online, but the materials that i have now arent working, got lm358 and copying the link you gave.. not working i have no idea if its the materials or something else my wiring etc.. and also planning on going to the hardware store to see and dismantle the parts that ill buy.
     
  7. CircuitMaster

    CircuitMaster

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    Dec 17, 2016
    Try measuring the voltage over the black diode, it should be "1.2-1.5VDC".
     
  8. kellys_eye

    kellys_eye

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    Jun 25, 2010
    ??? Doesn't make sense.

    this is something we cannot determine unless you show both the schematic you're building from AND the way you've done it.
     
  9. BobK

    BobK

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    An infrared LED would have Vf in that general range.

    Bob
     
  10. CircuitMaster

    CircuitMaster

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    Dec 17, 2016
    I don't know why my post was deleted, but I had this problem when I was building the same circuit recently, so I decided to ask.
     
  11. davenn

    davenn Moderator

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    Sep 5, 2009

    There is no post from you in this thread that has been deleted
     
  12. CircuitMaster

    CircuitMaster

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    Dec 17, 2016
    Thanks, I saw a notification that my post was deleted, maybe it was on another thread.
     
  13. elioacm

    elioacm

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    Jul 7, 2013
    ^hah... so me ill get in touch been busy assisting in a preschool event.. hope this thing my hobby project willl worrkk!! it would be great, im going to show the schematics and what after this event.. been delighted people replying thanks dudes aka fellow hobbyists teachers.. you make me so proud and making this my project a little bit brighter possiblIER is a big bonus! thx again.. ps: ill get in touch
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    I deleted it and then restored it.
     
    davenn likes this.
  15. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    After reviewing the OP's requirements for a proximity sensor, I would not recommend a PIR sensor for such an application. PIR sensors rely on the movement of objects with contrasting infrared emission, compared to the background infrared emission, and have zero range discrimination. PIR sensors will detect the movement of objects hotter or colder than the background infrared radiation at any distance within their field of view when the size and temperature of the objects provide enough contrast with the background radiation to present a usable signal.

    An active infrared emitter (IR LED) and a co-located infrared-responsive photo-diode, both devices pointing upward, appear to be the simplest way to create a proximity detector, responsive to a finger placed over (but not covering) the infrared emitter. A finger placed above the infrared emitter will reflect some of the infrared emitter radiation back toward the co-located photo-diode, which will then produce a signal that can be used to indicate proximity has occurred.

    Notice there are potential problems with this simple scheme. First, there is no way to distinguish infrared emission by the IR LED from other nearby infrared emitters. This can lead to "false positives" where these other infrared emitters indicate proximity is present when nothing desirable to detect is there. Second, sensitivity to variations in proximity detection range may cause unreliable operation or require frequent "tweaking" to establish operation. Still, this is an interesting project for beginners to try out. Infrared (or near infrared, which is what IR LEDs produce) radiation is a fascinating subject to explore, and the results (compared to visible radiation) are not always intuitive or even similar.

    One significant improvement that can be made in an infrared emitter and infrared photo-diode proximity detector is modulation of the infrared emitter with a square wave frequency of a few kilohertz. The signal from the photo-diode is then synchronously detected using the modulation frequency as a reference. The improvement in signal-to-noise ratio and detection sensitivity is enormous and usually well worth the extra effort.
     
    CircuitMaster likes this.
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