4017 Counter LEDs to stay on

Discussion in 'The Projects Forum' started by allenpitts, Jan 31, 2016.

  1. allenpitts

    Thread Starter Active Member

    Feb 26, 2011
    77
    7
    Hello All About Circuits forum,

    Using an Arduino to control a dozen 4017 - 555 circuits to sequence
    320 LEDs. The problem is the 4017 turns on LED 1 then turns it off
    and then turns on LED 2. The project wants to turn on LED 1 and
    leave it on and then turn on LED 2 and leave LED 2 on, then
    turn on LED 3 etc.

    Maybe the 4017 won't do this but does any one know if it will
    and if so how?

    Thanks.

    Allen in Dallas
     
  2. ISB123

    Well-Known Member

    May 21, 2014
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    Can you post the schematic?
     
  3. Colin55

    Member

    Aug 27, 2015
    191
    19
    Use 10 transistors to drive the LEDs in a staircase.
     
  4. dannyf

    Well-Known Member

    Sep 13, 2015
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    Fairly easy: you just need to send a fast pulses from the mcu, like this:

    '0', pause->1 pulse->'1', pause->2 pulses->'11', pause->5 pulses->'111', pause->7 pulses->'1111', pause....

    If you send those pulses fast enough, no human eyes can tell the intermediate states.
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    320 LEDs? I assume each one is sequenced individually? Steering diodes / transistors can do it with 4017's, but there will be a large matrix involved.
     
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    The 4017 enables only one output at a time. You could drive latches or OR gates with the 4017's outputs to get a staircase. Could you use LM3914 ICs in bar mode, instead of the 555/4017s?
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    Another possibility is to use a quad or 8 type D register that will clock over with a clock pulse. It would involve more ICs, but the logic is simple.

    http://ecee.colorado.edu/~mcclurel/dm74ls374.pdf

    http://www.nxp.com/documents/data_sheet/HEF4014B.pdf

    http://www.redrok.com/CMOS_CD4021BC_8-StageStaticShiftRegister_Fairchild.pdf

    There are others out there, this was just a sampling. I can draw up a simple type D approach if you are interested.

    ********

    I think post #4 was talking a multiplex approach.

    I am doing something whose basics might apply with multiplexing on

    http://forum.allaboutcircuits.com/threads/topo-map-with-flashing-led.119557/page-7#post-958798

    Post #100

    I have a 256 LED display drawn up in the zip file. It could easily be expanded, and use a uC to sequence it.
     
    Last edited: Feb 1, 2016
  8. allenpitts

    Thread Starter Active Member

    Feb 26, 2011
    77
    7
    Hello AAC forum,

    ISB123 I know this is not a schematic, more of pictorial but this the idea.
    [​IMG]

    Colin55 Forgive me, I not sure how to 'drive the LEDs in a staircase'. Could you amplify?
    I have hacked the Chaney 4431 and breadboarded the whole 555 to 4017 sequencer so
    not afraid to build a PCB if need be.
    [​IMG]
    This is 555 to 4017 operated by PIR sensor
    Thanks.

    Allen in Dallas
     
  9. Colin55

    Member

    Aug 27, 2015
    191
    19
    Use this:
    4017Staircase.gif
     
  10. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Welcome back, Allen. For a 320 LED bar graph I would suggest cascaded shift registers, for 320 steps & 8 bit SR's that is 40 SR's.
    The 74HC164 is the longest SR that I can find and can direct drive LED's at 10 mA @ 6V VDD. Connect the serial inputs on first SR to high & a clock advances the high - stage by stage to the end. A clear signal clears all stages. A 555 might have enough drive for the clock. The SR's can be distributed along the line of LED's to keep leads short.
     
    Last edited: Feb 1, 2016
  11. Wendy

    Moderator

    Mar 24, 2008
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    That would work for a small number of LED but the B-E drop on the lower levels would quickly eat up the voltages.
     
  12. Colin55

    Member

    Aug 27, 2015
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    The cct works on 12v
     
  13. Wendy

    Moderator

    Mar 24, 2008
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    If you used all 8 outputs that would be 4.9V drop, assuming a 0.7 V drop. The TS wants 360 outputs (an assumption on my part that I believe is the case). I like the base concept, but I suspect it is not workable. Steering diodes would have astronomical numbers associated, which probably kills that idea. So I'm back to the shift registers I referenced on post #7. Not sure if that meets the TS needs or not.

    A 19x19 grid would be 361 LEDs, which would lend itself to the multiplexed CPU idea.
     
  14. Colin55

    Member

    Aug 27, 2015
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    Just use 32 x 4017's
     
  15. Wendy

    Moderator

    Mar 24, 2008
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    Again 360 LEDs, each sequentially turns on with 360 transistors. 360 Outputs would require 52 4017s cascaded to each other.
     
  16. Wendy

    Moderator

    Mar 24, 2008
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    Just occurred to me, there is a sequential SCR circuit that does something similar, but the shift register seems like the best bet.

    Waiting on TS input.
     
  17. Colin55

    Member

    Aug 27, 2015
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    360 Outputs would require 52 4017s cascaded to each other.

    Should be:

    320 Outputs would require 32 x 4017s cascaded to each other.
     
  18. panic mode

    Senior Member

    Oct 10, 2011
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    just need 3 ICs like AS1130 or MAX6953 or similar
     
  19. Wendy

    Moderator

    Mar 24, 2008
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    I had a math error, it is actually 45. Cascaded 4017 only allow 8 pins out per chip, except for the 1st chip, which is 9 output. I had plugged in 7 outputs.

    Look at the data sheet.

    http://www.ti.com/lit/ds/symlink/cd4017b.pdf

    Page 3-55

    temp.png

    I use diode AND gates, which are quite convenient.

    Care to show us how? I'm interested. 320 LEDs is quite a few.
     
    Last edited: Feb 1, 2016
  20. Wendy

    Moderator

    Mar 24, 2008
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    Feeling a bit stupid, the TS did say he was using an Arduino, which puts it 9 pins of the 4017 usable (since there is no disable on the 4017.) 360 / 9 is 40.

    Still unsure what the TS wants to do large scale. A giant 320 LED bar graoh?
     
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