How can I convert TTL pulse train to current?

Discussion in 'Analog & Mixed-Signal Design' started by Ankit Garg, Dec 14, 2016.

  1. Ankit Garg

    Thread Starter New Member

    Dec 9, 2016
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    My input is TTL pulse having amplitude +5V, freq from 500KHz to 5Hz and duty cycle 50%.
    The output should follow this relationship
    I = C * Vc * freq

    Where,
    Vc= +5V (Pulse Amp)
    freq= pulse frequency
    C is the capacitor (to be connected in series with the input signal)
    The circuit should consists of diodes, capacitors and resistors only..

    Thanks in advance!
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    Is this homework?
    So how do you plan on doing this?
     
  3. shteii01

    AAC Fanatic!

    Feb 19, 2010
    4,667
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    I take it C and freq are constant. Is that correct?
     
  4. WBahn

    Moderator

    Mar 31, 2012
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    uh...

    Sure looks like it.

    :D :D :D
     
  5. WBahn

    Moderator

    Mar 31, 2012
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    What is I? The average current? The instantaneous current? The rms current? The current at noon in the River Thames?

    Where is this current to be measured?

    What attempt(s) have you make so far?
     
  6. Papabravo

    Expert

    Feb 24, 2006
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    Think really really hard and propose a possible method. That's what I would do.
     
  7. Ankit Garg

    Thread Starter New Member

    Dec 9, 2016
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    Capacitor value is fixed, input signal frequency is variable (range 5 Hz to 500 KHz)
     
  8. Ankit Garg

    Thread Starter New Member

    Dec 9, 2016
    4
    0
    I is the average current and the circuit shall output current proportional to the input freq.
     
  9. WBahn

    Moderator

    Mar 31, 2012
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    So is the current supposed to be DC? AC at the same frequency as the input signal?

    Where is the current that is being controlled? In the capacitor? In some resistive load?

    What attempt(s) have you made so far? Remember, this is YOUR homework problem (and it is pretty obviously a homework problem of some sort). So far we have seen nothing that indicates you are interested in anything more than getting someone else to do your work for you.
     
  10. dannyf

    Well-Known Member

    Sep 13, 2015
    2,196
    422
    use a rc network to turn the pulses into charges on the rising and falling edge.

    use a diode to gate the charges to either rising or falling edge.

    use another diode to direct the charges onto a capacitor.

    parallel the capacitor with a large resistor to turn the voltage on the capacitor into a current source.

    done.
     
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