tachometer help!!!

Discussion in 'The Projects Forum' started by onlyvinod56, Nov 9, 2008.

  1. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    Hi everyone.
    I need to display the speed of that motor on 7 segment display.
    I worked over BCD 2 seven segment decoder. But the pulses from speed sensor must be encoded to BCD.
    my sensor will generate "one pulse / revolution."
    I need to count the pulses in one minute and display them on 7 segment...

    thank you
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    What is the anticipated range of possible RPM? One through seven? 600 through 1750? Something else?
     
  3. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    maximum speed is 200 rpm. Iam going to control it from zero speed. It is a normal ceiling fan.
     
  4. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    The thread "sample and hold circuit" in this forum is created by me. This tachometer is the continuation of that project.
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,175
    397
    Scroll down to Similar threads, on to " designing of circuit elements of digital tach. " on down to Digi Dave's refferal, and find schematic. the 7474 is probably 74C74. Change timing of 555 to 60 sec. Consider 7555 CMOS version for longer time.
     
  6. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    200 rpm = 3 1/3 rps. If you use a wheel with 30 notches around the edge, or 30 each black and white alternations around the edge, you can read a falling edge transition every 1/100 second at 200 rpm.
     
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