10 LEDs - GROW BRIGHTNESS

Discussion in 'The Projects Forum' started by Thaahoo, Feb 23, 2015.

  1. Thaahoo

    Thread Starter New Member

    Feb 14, 2015
    17
    0
    I need to turn on ten LEDs one by one in the below fashion.

    GOING UP
    ==============
    0. No LED will light up
    1. First LED will light up
    2. 1st and 2nd LED will light up
    3. 1st, 2nd and 3rd LED will light up
    etc
    10. All the LEDs will light up

    GOING DOWN
    ==============
    11. Then 9 LEDs will light up
    12. 8 LEDs will light up
    etc
    20. First LED will light up
    21. No LED will light up

    The process continues.

    Which IC is used for this circuit? How to wire it?
     
  2. pwdixon

    Member

    Oct 11, 2012
    488
    56
    I think you are looking for an LM3914 but you will need a rising/falling analogue voltage to create the progressive LED effect. Alternatively you could program a micro or use something like an Arduino.
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
    745
  4. Thaahoo

    Thread Starter New Member

    Feb 14, 2015
    17
    0
    I am Looking for an Arduinoless solution.
     
  5. Thaahoo

    Thread Starter New Member

    Feb 14, 2015
    17
    0
    Knight Rider circuit is not as per my requirement. It is lighting one by one. But the first LED will not stay ON until all 10 light up.
     
  6. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
    745
    Set it to bar mode instead of dot, with pin 9, you clearly dont read the posted info....
     
  7. Thaahoo

    Thread Starter New Member

    Feb 14, 2015
    17
    0
    Sorry. I couldn't notice that.
    One doubt. Can I replace LM4558N with a 555 timer? If not, why?
    Thanks in advance!
     
  8. pwdixon

    Member

    Oct 11, 2012
    488
    56
    Dodgydave already said it was an option to swap in a 555.
     
  9. Thaahoo

    Thread Starter New Member

    Feb 14, 2015
    17
    0
    What I understand is LM3914N needs a steadily increasing voltage input to show the graph. Can 555 produce that steadily increasing voltage output?
     
    Last edited: Mar 1, 2015
  10. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
    745
    Yes across the charge capacitor on pins 1,2, you can buffer it if you want or feed the input of the Lm3914 direct from pin 2 of the 555,

    the capacitor charges from 1/3 to 2/3 of the supply voltage, ( thats 4V and 8V on a 12V supply) just set the ref HI. and ref LO of the Lm3914 .
     
    Last edited: Mar 1, 2015
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