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Sensing circuit for line following robot

Discussion in 'Microcontrollers, Programming and IoT' started by Areeha Durrani, Jul 13, 2015.

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  1. Areeha Durrani

    Areeha Durrani

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    Jul 8, 2015
    I have been trying a no of IR sensing circuits for my line following robot but since it's my first time,em facing a no of problems... I have been trying circuits using IR transmitter and receiver and LM324 but continuously em getting 0 at the output of serial monitor in the arduino..
     
  2. Arouse1973

    Arouse1973 Adam

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    1,092
    Dec 18, 2013
    Show us a circuit diagram.
     
  3. Areeha Durrani

    Areeha Durrani

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    Jul 8, 2015
    image.jpg
     
  4. cjdelphi

    cjdelphi

    1,161
    108
    Oct 26, 2011
    either your circuit is wrong or the opamp is faulty...

    are you measuring a voltage across the ir led when it's operational?
     
  5. Areeha Durrani

    Areeha Durrani

    45
    1
    Jul 8, 2015
    It's around 1.13 v around transmitter and 0.11v around receiver... I just don't get it
     
  6. Colin Mitchell

    Colin Mitchell

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    Aug 31, 2014
    The first thing you do is put a 10k pot in place of the 10k and IR receiver and adjust the pot and let us know if the output immediately changes from LOW to HIGH.
     
  7. Arouse1973

    Arouse1973 Adam

    5,171
    1,092
    Dec 18, 2013
    You are using an op-amp as a comparator which is something I try to discourage.

    But you have designed it now, and I think R2 is too high, you are using a photodiode which won't have a huge amount of current gain versus irradiance. Can you tell us what IR devices you are using.

    Edit R2 is too low a value.

    Thanks
    Adam
     
    Last edited: Jul 16, 2015
  8. Areeha Durrani

    Areeha Durrani

    45
    1
    Jul 8, 2015
    I have tried using a 10k pot in place of R2.. But there's no change in the output..
     
  9. Areeha Durrani

    Areeha Durrani

    45
    1
    Jul 8, 2015
    Sir,is it possible that I don't use the comparator and make the sensing circuit without it?i am new to all this,that's why want someone to guide me...I also want to confirm that I am checking the output at the first pin of IC and in order to check the results,I have connected it to the second digital pin of arduino and the code is something like:
    VoidSetup(){
    PinMode(2,OUTPUT);
    Serial.begin(9600);
    Serial.println((digitalRead(2));
    }
     
  10. Areeha Durrani

    Areeha Durrani

    45
    1
    Jul 8, 2015
    Instead of input,I wrote output...
    Sir,i just removed the resistor with IR receiver and directly connected it with 5V and changed 330 Ω with 220Ω,so I got 5.32v at pin 1 of IC...but still 0 output at the serial monitor of arduino..why?i don't get it...
     
  11. Areeha Durrani

    Areeha Durrani

    45
    1
    Jul 8, 2015
    Do you have a better suggestion?
     
  12. Arouse1973

    Arouse1973 Adam

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    1,092
    Dec 18, 2013
    Increase the value of R2, 470K. You still haven't told us what devices you are using. How far apart are the TX and RX devices?
    Adam
     
    Areeha Durrani likes this.
  13. Colin Mitchell

    Colin Mitchell

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    Aug 31, 2014
    I will make it simpler for you.
    Replace the IR diode with a 10k resistor. This means you have half rail on the + input. Now adjust the 10k pot and with a LED and 220R on the output you will see the LED come on.
     
    Areeha Durrani and Arouse1973 like this.
  14. Areeha Durrani

    Areeha Durrani

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    Jul 8, 2015
    The led is glowing even now sir with my setup of circuit
     
  15. Areeha Durrani

    Areeha Durrani

    45
    1
    Jul 8, 2015
    image.jpg This is how I have made the circuit
     
  16. hevans1944

    hevans1944 Hop - AC8NS

    4,685
    2,193
    Jun 21, 2012
    You STILL haven't provided us with part numbers or specifications for the infrared emitter and the diode infrared detector.

    Have you used your multimeter to measure the voltage at the cathode of the IR Receiver RX? Measure the voltage there with respect to GND with the light path both blocked and then un-blocked and tell us what you find.

    A reverse-biased infrared-sensitive photo-diode is not a very sensitive detector, and even less so if you are trying to use an infrared LED emitter as a detector.
     
    Areeha Durrani likes this.
  17. Areeha Durrani

    Areeha Durrani

    45
    1
    Jul 8, 2015
    Alhamdulillah got my problem solved...thank you all and Jazak Allah for ur help..
     
  18. Areeha Durrani

    Areeha Durrani

    45
    1
    Jul 8, 2015
    :):)
     
  19. Arouse1973

    Arouse1973 Adam

    5,171
    1,092
    Dec 18, 2013
    Care to tell us what it was then?
     
  20. Areeha Durrani

    Areeha Durrani

    45
    1
    Jul 8, 2015
    One of the connecting wire was broken from the inside..
     
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