Identifying unknown DAC-counter circuit

Discussion in 'Homework Help' started by cgrell, Feb 27, 2015.

  1. cgrell

    Thread Starter New Member

    Feb 27, 2015
    2
    0
    [​IMG]
    "This circuit is a waveform generator, built using a DAC 312 using B5 to B12, with B1 to B4 'reset', and using 74191 counters.
    Build it and determine v(out)'s waveform."

    I am desperate with this because this circuit seems too weird. I tried building it myself but I can't find the right pinout (I was asked to build it using a DAC0832 instead of the DAC 312).

    Also, I can't seem to simulate it because the simulator does not have the components.

    Thanks in advance
     
  2. nDever

    Active Member

    Jan 13, 2011
    154
    4
    This particular DAC configuration generates a sawtooth waveform. As the counter counts up, the output voltage level increases, and when the count resets, the voltage level drops back to Vss to start again.

    You could try alldatasheet.com for the datasheet. Also try octopart.com.
     
  3. cgrell

    Thread Starter New Member

    Feb 27, 2015
    2
    0
    Thank you very much! Do these pictures match the desired output?

    [​IMG]
    [​IMG]
     
  4. nDever

    Active Member

    Jan 13, 2011
    154
    4
    No problem. The pictures do resemble the shape of the voltage output of the circuit above. Of course, the amplitude of the signal is determined by the power rails on the DAC. In the schematic, the supply rail is 12V, so, the output will ramp from 0V to 12V with an 8-bit resolution.
     
  5. WBahn

    Moderator

    Mar 31, 2012
    17,777
    4,805
    Please do not just provide answers to homework problems. Provide guidance, hints, suggestions, and observations, but leave something substantive for the student to do for themselves.
     
    bertus likes this.
  6. nDever

    Active Member

    Jan 13, 2011
    154
    4
    Sorry. I got carried away... :oops:
     
  7. WBahn

    Moderator

    Mar 31, 2012
    17,777
    4,805
    That's okay. It's easy to do and it happens to all of us from time to time.
     
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