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Analog output

Discussion in 'Electronic Basics' started by BR, Oct 5, 2003.

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  1. BR

    BR Guest

    Looking for inexpensive 12-bit analog output and a few i/o lines via parallel
    port. Schematics, products?
     
  2. --------------
    Inexpensive, use 74HC574 octal latches, and a 12 bit R-2R ladder DAC.

    http://www.armory.com/~rstevew/Public/R-2R_DACs/
    http://www.armory.com/~rstevew/Public/R-2R_DACs/R-2RLadderDAC.gif
    http://www.armory.com/~rstevew/Public/R-2R_DACs/R-2R_10DAC.gif
    http://www.armory.com/~rstevew/Public/R-2R_DACs/R-2R_8bitDAC.gif

    http://www.armory.com/~rstevew/Public/Tutor/PinOuts/parallel.gif

    Use the control lines pins 1, 14, 16, 17 to strobe the latches.

    -Steve
     
  3. John Fortier

    John Fortier Guest

    Better definition needed. Words please and thankyou omitted. Desire to
    help not evoked.

    John
     
  4. BR

    BR Guest

    Please?

    Thank you.

    Ben
     
  5. BR

    BR Guest

    Ok, I need to control one Servodisc motor. The H-bridge for the motor has a
    voltage input that controls the PWM. It also has two ports for forward and
    reverse signals. I was looking around and found a simple schematic for an 8
    bit d/a (AD7524) which is apparenty nothing more than connecting the 8 data
    lines of the parallel port to the DAC. Now I may just try getting along with 8
    bit resolution, but if I need more resolution, how do I load two bytes into a
    12 bit DAC? (realizing that 4 bits will be discarded). I will probably figure
    out this simple project myself eventually, however perhaps there is a way I
    could be prevented from using more chips than necessary to accomplish this.

    Help appreciated.

    Ben
     
  6. John Fortier

    John Fortier Guest

    OK Ben, Go to rswww.com. You'll need to register, which is free, and then
    you can search out DACs from the electronics section. You can download
    manufacturers data sheets in PDF and choose the DAC which comes closest to
    your requirements. You don't have to order anything to get all the
    information, and, since they are a UK company, you may not want to pay the
    shipping charges, although if it comes by mail, it's cheap.

    I use RS not only as a supplier, but also as a research tool when it comes
    to choosing suitable components for prototypes.

    Regards

    John
     
  7. BR

    BR Guest

    John, I can't register. Doesn't recognize US zip code. I download data sheets
    from various mfr's websites anyway. The DAC isn't critical.

    Regarding what I'm trying to figure out, this pdf

    http://www.physics.otago.ac.nz/electronics/papers/HicksBahr99.pdf

    shows a 12 bit ADC feeding a parallel port. Although they are utilizing EPP
    mode, SPP will be fast enough. It's just that part of the circuit that buffers
    the 4 bits from the ADC that's later transferred to the parallel port that I'm
    interested in, or for a DAC the situation would be reversed.

    How about this DAC1222
    http://www.jameco.com/Jameco/Products/ProdDS/14980.pdf

    Ben
    [/QUOTE]
    OK Ben, Go to rswww.com. You'll need to register, which is free, and then
    you can search out DACs from the electronics section. You can download
    manufacturers data sheets in PDF and choose the DAC which comes closest to
    your requirements. You don't have to order anything to get all the
    information, and, since they are a UK company, you may not want to pay the
    shipping charges, although if it comes by mail, it's cheap.

    I use RS not only as a supplier, but also as a research tool when it comes
    to choosing suitable components for prototypes.

    Regards

    John
    [/QUOTE]
     
  8. BR

    BR Guest

    MAX508
     
  9. Wade Hassler

    Wade Hassler Guest

    The schematic in the paper you referenced shows how:
    Put upper 4 bits on parallel port data lines
    Latch upper 4 bits to 74x574 with a control line
    Put lower 8 bits on parallel port data lines
    Send 12 bits to DAC with another control line


    Wade
     
  10. John Fortier

    John Fortier Guest


    Fair enough!
     
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