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Circuit schematic for LED tachometer?

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by wsemajb, Jun 17, 2010.

  1. wsemajb

    wsemajb New Member

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    My circuit/electronics skills are pretty limited to following schematics and building a circuit directly from them.

    I'm trying to find a circuit to get me 99 percent of the way toward interfacing the following two items for indicating ml/min water flow...

    http://img.diytrade.com/cdimg/163371/3406791/0/1174985167/MS_Mini_flow_sensor.jpg
    15 LED Circular & Linear Bargraphs - LEDtronics - 12991

    I'd like the bargraph to register 0 - 2000 ml/min. With straight up (middle) bar indicating 1000ml/min

    I realize that this is essentially an LED bargraph tachometer reading pulses from a hall effect switch.
    Since RPM measurement with hall switches is such a common task, I'm hoping that there exists
    some schematic involving the following ICs to accomplish this with little additional conditioning
    or (hopefully no) programing.

    LM2917 freq/volt converter IC
    LM3914/15/16/17 LED driver ICs

    Would the following page be of use to me?

    LM2917N, LM3914, Tachometer, PCB


    Thanks so much.

    Brad
    Last edited: Jun 17, 2010
  2. wsemajb

    wsemajb New Member

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    Am I wrong in approaching this as a tachometer?
  3. ericgibbs

    ericgibbs Super Moderator Most Helpful Member

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  4. Reloadron

    Reloadron Well-Known Member

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    Hi Eric

    Maybe it is me but the Link no workie, workie?

    Ron
  5. ericgibbs

    ericgibbs Super Moderator Most Helpful Member

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    Last edited: Jun 18, 2010