LED bar graph wanted

Discussion in 'General Electronics Chat' started by Freddy Adelvard, Nov 22, 2008.

  1. Freddy Adelvard

    Thread Starter New Member

    Nov 22, 2008
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    I have a 5K Ohm linear potentiometer built into a servo.
    I want 11 light diodes (LED) in a row, indicating the potentiometer position, i.a. when the pot-meter says
    0 Ohm = 1 LED lit
    500 Ohm = 2 diodes lit
    1000 Ohm = 3 diodes lit
    o.s.v.
    5000 Ohm = all 11 diodes lit
    LEDs are 5 mm 2.2 volts 20 mAmp
    Power supply between 12 and 14 volts dc.
    Who can and want to help me with that circuit diagram?
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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  3. beenthere

    Retired Moderator

    Apr 20, 2004
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  4. hgmjr

    Moderator

    Jan 28, 2005
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    If the limit of 10 LEDs imposed by the LM3914 is a deal-breaker, you could cascade two LM3914's and go for 20 LEDs.

    hgmjr
     
  5. Audioguru

    New Member

    Dec 20, 2007
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    The LM3914 will not light the first LED when the input is 0V.
    So you need to light the first LED with a resistor. It will always be lit.

    The LM3914 steps are linear. Feed a constant current to the resistor. The LM3914 lights 10 LEDs when the resistance is 5k then one LED will light when the resistance is 500 ohms. Plus the LED that is always turned on.
     
  6. Freddy Adelvard

    Thread Starter New Member

    Nov 22, 2008
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    0
    Thank you very much for the quick and constructive answers, especially to Audioguro for the information about "the missing light" in the first diode. My problem has been solved.
    /Freddy
     
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