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Amazing and challenging problem!

Discussion in 'General Electronics Discussion' started by Shubham_01, Apr 15, 2021.

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  1. Shubham_01


    Apr 15, 2021
    To all the electronics enthusiasts I have the following challenging problem! Can anyone help me in solving the problem?




    [Mod Note: cropped and resized large images and placed inline to make viewing easier]
    Last edited by a moderator: Apr 15, 2021
  2. Bluejets


    Oct 5, 2014
    Not quite sure what you want.........
    Description of your application, what you have done so far and the problem you are having would be helpful.

    No one is going to design anything for you.
    Harald Kapp likes this.
  3. ratstar


    Aug 20, 2018
    Its a nice problem, but I guess everyone here likes working on real applications, not just solving quizzes.
  4. Martaine2005


    May 12, 2015
    Interesting homework.
    How can this possibly work given tolerances and 4 or 5 band resistors?
    I'll watch this for my own benefit.

  5. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    We will not do your homework. What you can expect is our help in finding your own solution.

    What I understand:
    You measure the resistance, then convert the measured value into a 3 digit code and light up the LEDs according to the equivalent color code. Is that what you want?
    This is how I would tackle this task using the list of components you show (unfortunately there is no microcontroller in the list, that would make matters quite easy):
    • Design a way of measuring the resistor. This is where the ADC comes into play. With "only" 10 bits you will need a kind of range selection to be able to measure resistances over the full range available with 3 color bands. Hint: think of the range selector as the multiplier band.
    • You will also need a kind of state machine that controls the range selection and the ADC. Since at the tart of the measurement the resistance value is unknown, the state machine will have to test each range (each multiplier) and check whether the ADC's output gives a valid code for bands 1 and 2. If not, the next range needs to be selected.
    • Design a circuit that converts the ADC's output into a 3 digit BCD code - I recognize the ADC delivers BCD, so no need for an extra conversion stage.
    • Design a circuit that converts the BCD code into a 1-hot code (also known as 1-out-of-n code)
      [*]Design a circuit that multiplexes the 1-hot code (30 lines) into a multiplexed 1-hot code (3+10 lines)
      [*]Design a circuit that uses the multiplexed signal to drive the LEDs.
      - After re-reading the task description, this is also not required as the LED block accepts 3 × 4 Bit BCD values for digit1, digit2 and exponent.
    • You will also need to design an oscillator to drive the multiplexing (and possibly the ADC)

    Of course you are free to design the circuit in a different way. For example you could directly convert from BCD to multiplexed 1-hot without the intermediate generation of a 1-hot code for each digit by multiplexing the BCD code.
    Decide which implementation fulfills the requirements best (in your opinion). For example look at the cost of different solutions.
    Present your (intermediate) results and ask when you are stuck. We'll help you along.


    Harald Kapp
    Last edited: Apr 16, 2021
    Martaine2005 likes this.
  6. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    The task description states "You use a custom code for an oder from a special company which does not require tolerance rating" i.e. ideal resistors with 0 tolerance.
    Consequently the image shows an indicator panel with only 3 rows of LEDs: digit 1, digit 2, multiplicator.
  7. bertus

    bertus Moderator

    Nov 8, 2019

    With a 2 digit base, the E24 series could be used:
  8. Shubham_01


    Apr 15, 2021
    Guys you got me wrong!!!
    I shared because I thought its a challenging and interesting problem and you all will love.
    Its not a homework problem guys!!!
    I hope someone will be ready to work with me and help me simulate this on a simulator.

    [Mod note: email removed to avoid spamming]
    Last edited by a moderator: Apr 28, 2021
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