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Tilt Angle between two LDR

Discussion in 'General Electronics Discussion' started by zackfair, Dec 12, 2015.

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  1. zackfair

    zackfair

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    Dec 12, 2015
    hi, i'm am engineering student and i'm running for my project right now. Lecturer ask me to find "tilt angle between to two LDR". he said just use two LDR and differential op-amp. how i'm supposed to conduct the experiment and i don't know how the circuit was? can anyone help me cause i'm really need the method for this experiment? thanks a lot

    p/s: sorry for my bad English
     
  2. Martaine2005

    Martaine2005

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    May 12, 2015
    Hi zackfair,
    Your English is good, but the question is not very clear. Do you mean the angle at which they will turn on?
    The datasheet for the particular component will give that information.
     
    davenn likes this.
  3. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    Yes please explain more.
     
  4. zackfair

    zackfair

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    Dec 12, 2015
    I forgot to tell that i'm running for analog project basically. I thought it was something like in the picture as my lecturer explained to me. When the LDRs received light, the difference voltage that they produced will receive by op-amp. Then, from the op-amp, tilt angle will be determine. It is tilt angle of light?
     

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    Last edited: Dec 13, 2015
  5. Martaine2005

    Martaine2005

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    May 12, 2015
    I think I understand, but wait for a "proper answer"....
    The op-amp is used as a comparator and compares two input voltages. As LDR1 detects more light, the resistance drops and voltage increases to the op-amp.
    As LDR2 has less light, the resistance rises and voltage drops..
    It's the op-amps job to compare the two and keep a 'stable' input.
    When you tilt (move) the light source above the LDRs, or move it side to side, the voltages will be rising and falling.
    I am not sure if that answers your question or not..

    Martin
     
    Last edited: Dec 13, 2015
    zackfair likes this.
  6. zackfair

    zackfair

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    Dec 12, 2015
    Yes, it is!! I just can't figure out how the circuit was and how to get the angle. Can you help me?
     
  7. Martaine2005

    Martaine2005

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    May 12, 2015
    To be honest, I don't know what is meant by 'angle'..
    If you can explain that, somebody can help you..

    Martin
     
  8. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Just a guess: look up "solar tracker" or "sun tracker". Here is an example. Note that for good tracking you will have to place an opaque shield at 90 ° between the two LCDs so that one LDR receives more light than the other when not aligned to the source of light.
     
    Tha fios agaibh likes this.
  9. Tha fios agaibh

    Tha fios agaibh

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    1450025384034-1.jpg
    Only one op amp?
    Something simple like this would go on/off with a narrow angle. But not very functional.
     
  10. zackfair

    zackfair

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    Dec 12, 2015
    No, he not said just use only one op amp. Hmm.. I need to to ask him by face-to-face back what he want actually as he don't reply my email.
     
  11. GPG

    GPG

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    Sep 18, 2015
    Any power supply restrictions?
     
  12. zackfair

    zackfair

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    Dec 12, 2015
    No, I guess.
     
  13. GPG

    GPG

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    Sep 18, 2015
    Bipolar supply, connect ldrs in series junction to amp+ set gain using - input. Angle the ldrs to left and right
     
  14. zackfair

    zackfair

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    Dec 12, 2015
    sorry sir, can I have an image?
     
  15. GPG

    GPG

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    Sep 18, 2015
    If you mean a picture,no. If you mean a circuit, that's your job
     
  16. zackfair

    zackfair

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    Dec 12, 2015
    thank you sir for your help
     
  17. Colin Mitchell

    Colin Mitchell

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    Aug 31, 2014
    You really need to attend 3 more years of your Bachelors Electronics classes before you can entertain the possibility of designing the type of circuit you request.
     
  18. Martaine2005

    Martaine2005

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    May 12, 2015
    Zackfair,
    Your lecturer did not explain to you as in your diagram!!
    Open loop and closed loop are very different.
    Without feedback, the op-amp has no idea what you want.
    Inverting and non invertinting are also different.
    Depending on the external circuitry, it can simply turn off and on, or output the diffence of the two and use that.
    Here is a video I have been watching for months......It doesn't matter how many times I have paused/played this, I understand the moment.....After that I forget!!

    Martin
     
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