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Hacking a digital tape measure?

Discussion in 'Electronic Design' started by Ken Moffett, Mar 7, 2007.

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  1. Ken Moffett

    Ken Moffett Guest

    I'm involved in a project where the perfect, cheap transducers
    would be some of the new digital tape measures...if they can be
    hacked for an electrical (quadrature?) output. Some corrent
    ones for sale (sorry about the word wrap):

    Has anyone tried this?
  2. Ken Moffett

    Ken Moffett Guest


    <(©¿©)> An apple a day keeps the doctor away.
    Two apples a day gets the doctor's OK.
    Five a day makes you a fruit grower like me.

    Karl Townsend
  4. Guest

    I have not tried that, but an easier way might be to use a thing made
    to work that way. Several manufacturers make linear measuring units
    that work sort of like one of those spring loaded gadgets that you
    hang your keys on your belt with. It has a cable that pulls out and
    retracts with a spring. The internal spool rotates as the cable is
    pulled out, and that gives a quadrature output designed to easily
    relate to the distance the end of the cable has moved.

    I used a couple on a job at work a few years back, it worked great.
    Not quite linear scale resolution/accuracy, but pretty darn good +/- a
    few thousandths IIRC with maybe 4 foot range. That was plenty for our
    application, and it was not nearly as costly as an equivalent linear
    scale and much more compact.

    Unless you have some compelling reason to use a hacked digi-tape,
    this may be a good way to go. The name of the company that makes these
    is escaping me at the moment, but some Google work ought to turn it

    Hope that helps.

    AL A.
  5. ff

    ff Guest

    Check out the last link. I hope the tape measure is more accurate than
    the advertisement. It states, Accuracy: +/- 0.6"
  6. John  Larkin

    John Larkin Guest

  7. IanM

    IanM Guest

  8. Rich Grise

    Rich Grise Guest

    FWIW, Pan:
    has a "view" menu item where one of the options is a "wrap article body"

    And the "compose" window has an option to wrap or not to wrap.

    Admittedly, it's not too good at picking up various file associations with
    clickable links, but that's not that big of a deal - I do it so seldom
    (click links), that a three-click workaround is no hardship. :)

  9. Phred

    Phred Guest

    Why would you want to hack a tape measure??

    If the digital tape measures are that cheap, just buy a couple and
    open them up to find the encoder. I am pretty sure it is just a photo
    electric light cell (opto tansmitter and receiver) and it reads the
    encoded strip on the tape. Kinda like a big, long barcode, just with a
    counter and positioning information.

    If your really that interested do a google patent search on it.

    I am sure you will come up with quite a few hits.
  10. Ken Moffett

    Ken Moffett Guest

    That's exactly what I had in mind. I just wondered if anyone
    had tried it. One thing that I wondered about was: are the
    quadrature marks fractional and converted to cm on the
    display or visa versa. Anyway, I ordered a Sterrett Digitape
    Saturday...should be here Wednwesday. I'll let you know what
    I find.

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