Sequencing LEDs

Discussion in 'The Projects Forum' started by craigfoo, Dec 5, 2013.

  1. craigfoo

    Thread Starter New Member

    May 16, 2013
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    I have 12 LEDs that I want to turn on/off in this order:

    Each one will be on for a period of time before shutting off.

    1 on

    2 on

    1 off / 3 on

    2 off / 4 on

    3 off / 5 on

    4 off / 6 on

    5 off / 7 on

    6 off / 8 on

    7 off / 9 on

    8 off /10 on

    9 off / 11 on

    10 off / 12 on

    11 off

    12 off

    I think a MCU would be best for this but is there something I can do in the analog domain? I was thinking a couple of 555 timers but then my part count is getting high. Thoughts?
     
  2. gerty

    AAC Fanatic!

    Aug 30, 2007
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    You need to give more info, see questions above, and
    fill in the rest of the blanks
     
  3. craigfoo

    Thread Starter New Member

    May 16, 2013
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    For example:

    Each LED is on for 30 secs with a 15 sec interval between them. They're cascading.

    LED1 comes on
    LED2 comes on 15 secs after LED1
    LED1 turns off after 30 secs of being on, LED3 turns on
    LED2 turns off after 30 secs of being on, LED4 turns on
    etc.
     
  4. gerty

    AAC Fanatic!

    Aug 30, 2007
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    Sounds like what you're looking for is the "Knight Rider " circuit, always 2 on at a time. I think I have one somewhere , let me take a look.
     
  5. gerty

    AAC Fanatic!

    Aug 30, 2007
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  6. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    How about a 555 15 sec clock, 2 cascaded 4017's, 12 NOR's, & 12 inverting drivers?
    Or substitute 2, 8 stage parallel out shift registers & anotrer 555 for the 4017's?
     
    Last edited: Dec 5, 2013
  7. craigfoo

    Thread Starter New Member

    May 16, 2013
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    Thanks Gerty, these are cool!

    Bernard, doing a little more research, I was thinking of something similar. How about two 555 timers each at a 30 sec clock and two 4017s. The first 555/4017 set would run the "odd" LEDs (LED1, LED3, etc.) and the second 555/4017 would start 15 secs later and run the "even" ones.
     
  8. Bernard

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    Worth looking into.
     
  9. absf

    Senior Member

    Dec 29, 2010
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    What about one 555, one 4013 and 2x 4017 like the attached?

    Allen
     
    Bernard likes this.
  10. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    absf, your statememt is exactly what I was going to say this morning, except you had the full schematic to go with it. Only question now is this a continuous operation or does it start & stop?
     
  11. BobTPH

    Active Member

    Jun 5, 2013
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    I'd still go with 1 14 pin microcontroller.

    Bob
     
  12. absf

    Senior Member

    Dec 29, 2010
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    It is continuously running once the sequence ends, it would start all over again. If it should stop after running one cycle, I would put a NAND gate at the output of the 555.

    But I agree with Bob that using a uC is the best solution.

    Allen
     
  13. craigfoo

    Thread Starter New Member

    May 16, 2013
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    Great feedback! Thanks!

    A uC does seem like the right solution but how would that affect the cost of getting a circuit like this manufactured? I would think that dealing with programming a part would be a much greater cost than just having an open loop, no software solution. Does anyone have experience with this?
     
  14. tracecom

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    Apr 16, 2010
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    Given decent volume, the μC chips will come pre-programmed from the manufacturer.
     
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