need help in project

Discussion in 'The Projects Forum' started by mindgame2, Jan 25, 2009.

  1. mindgame2

    Thread Starter Member

    Jan 24, 2009
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    wanted to calculate the speed of small dc machine using laser beam
    i have figured out that i have to use decade counter along with the seven segment decoder along with seven segment display but could not figured out what to use for detecting the laser beam as the shaft of dc machine would cut laser beam
    i have an idea to use either photo diode or photo transistor
    but does not know what to use and how to use it:confused:
     
  2. mik3

    Senior Member

    Feb 4, 2008
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    First, how will you calculate speed with a decade counter?
     
  3. mindgame2

    Thread Starter Member

    Jan 24, 2009
    12
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    there would be a stick or some other kind of hinderence on the shaft of dc motor
    the number of times the shaft cuts the laser beam the number of times the laser beam would not fall on the photo diode or photo transistor
    thus it would produce negative clock pulse required for the decade counter
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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  5. mik3

    Senior Member

    Feb 4, 2008
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    Yes, but by counting the times the laser beam will be cut is not enough. You have to make some other calculations too.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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  7. mindgame2

    Thread Starter Member

    Jan 24, 2009
    12
    0
    what do you mean by some other calculations????
    i am planning to calculate first the "rps" of the machine using stop watch from which the "rpm" would be calculated of the dc machine
    if you have any alternative idea then give it to me
    otherwise my only issue is about detecting the laser light
     
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