ADC using volTage DivideR

Discussion in 'Homework Help' started by karunadas@hotmail.com, May 2, 2013.

  1. karunadas@hotmail.com

    Thread Starter New Member

    May 2, 2013
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    I made an circuit in breadboard as done in the picture like in the attachment. Well I also made an trial circuit on TINA PRO software and when I do simulation than I get problem.

    Well the results should be like for __________ Vin Binary output

    -------------->> LED 1 LED 2

    For 0v --> off off
    For 1v -- > on off
    For 2v --> off on
    for 3v --> on on

    My Vref is 12 volt. Well on doing the practical everythng works fine till 0v and 1v. but after i give Vin as 2 volts, both led glows instead of one glowing and other off. Please help and tell me where I am wrong.
     
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  2. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    Your telling me the breadboard worked as you desired and the simulation didn't?
     
  3. WBahn

    Moderator

    Mar 31, 2012
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    Are you sure that the non-inverting input of both opamps is supposed to be tied to the positive rail?

    How, given this circuit, is the output of an opamp supposed to change from one state to the other and then change back as the input voltage is increased?
     
  4. karunadas@hotmail.com

    Thread Starter New Member

    May 2, 2013
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    the voltage divider should work but itz not working..any help.. even the software says no..
     
  5. WBahn

    Moderator

    Mar 31, 2012
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    You say it should work but you won't answer my question of how it is supposed to change from one state to another and then back. Can you explain WHY you think that LED1, after going on at 1V, should go back off at 2V?
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    I did not see a part number on the LED, did I miss it or something? It is very important.
     
  7. karunadas@hotmail.com

    Thread Starter New Member

    May 2, 2013
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    ... what is a part no???
     
  8. WBahn

    Moderator

    Mar 31, 2012
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    What part of that PDF makes you think that LED1, after going on at 1V, should go back off at 2V?

    You have a simple electronic circuit. ANALYZE IT!!! Show your efforts!
     
    karunadas@hotmail.com likes this.
  9. WBahn

    Moderator

    Mar 31, 2012
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    Read my Post #3 again.

    WHY are you using the input signal to power the opamps?
     
  10. karunadas@hotmail.com

    Thread Starter New Member

    May 2, 2013
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    yes I had replaced the power input of both pin 4 and 7 by another source of +- 5V. Still it does not works... can u please make me understand the circuit...?? I am very amateur
     
  11. karunadas@hotmail.com

    Thread Starter New Member

    May 2, 2013
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    actually that was what I was thnkng..but my supervisor kept on telling that itz d circuit
     
  12. karunadas@hotmail.com

    Thread Starter New Member

    May 2, 2013
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    Can anyone of you please provide me a CIRCUIT DIAGRAM of 2 BIT ADC using op-amps??
     
  13. WBahn

    Moderator

    Mar 31, 2012
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    Could you please post an updated schematic so that we can see what you are working with?

    Also, please tell us very clearly what your PHYSICAL circuit is doing and, separately from that, what your SIMULATED circuit is doing.
     
  14. WBahn

    Moderator

    Mar 31, 2012
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    Please stop the text speak, it is not appreciated here.

    And please try to write in complete thoughts. I have know idea what "that" was that you were thinking or which circuit "itz" is refering to.

    You need to learn to communicate clearly and precisely if you ever hope to get anywhere in engineering. Consider this a really good opportunity to practice.
     
  15. WBahn

    Moderator

    Mar 31, 2012
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    Uhmmm.... Did you READ the Lab Handout that you posted? The whole point of the lab is for you to learn about the 3-bit ADC that they walk you through and give you all of the circuit diagrams for. You should be able to modify that to cut it down to a 2-bit if you so desire.

    Don't just ask for us to give you the solutions to your homework. You need to show an honest effort and ask specific questions that are causing you trouble.
     
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