Connect with us

LED sequencer

Discussion in 'Beginner Electronics' started by Chris W, Oct 26, 2003.

Scroll to continue with content
  1. Chris W

    Chris W Guest

    I want to flash LED's in an interesting sequence and was wondering if
    there some pre made device that could do this of if it could be made
    with out too much difficulty. It's hard to describe the sequence so I
    will use ascii art to show the sequence. O = on, X = off.

    OOOXXXXXXX
    XOOOXXXXXX
    XXOOOXXXXX
    XXXOOOXXXX
    XXXXOOOXXX
    XXXXXOOOXX
    XXXXXXOOOX
    XXXXXXXOOO

    Then repeat or maybe reverse it and then repeat. This shows 10 LEDs,
    but I may be using 15 or 20. I also have 2 different applications for
    this. In one I each of the 15 to 20 positions will represent a single
    high intensity LED. The other applications requires more intensity so
    each position will be a group of 5 or 10 LEDs, so the circuit needs to
    be handle enough current for than many LEDs.

    --
    Chris W

    "They that can give up essential liberty
    to obtain a little temporary safety
    deserve neither liberty nor safety."
    -- Benjamin Franklin, 1759 Historical Review of Pennsylvania
     
  2. Hi Chris.

    In my opinion, no single logic device will be able to handle it, or the
    design effort isn't worth it (even using shift registers + initialization
    logic around can lead to unexpected results and be very big).
    The two obvious solutions would be :
    - either an old EPROM (1 for 8 LED outputs) you program with the LED
    sequence and you scan with a counter
    - or a microcontroller with the program to output the sequence on its output
    ports.

    OK?
     
  3. Chris W

    Chris W Guest

    The microcontroller sounds like the way to go to me. I haven't done any
    electronics in years though. I am a programmer by profession now so I don't
    think I will have a hard time learning to program the microcontroller but I have
    now idea where to look to find one that is reasonably cheap and preferably
    rather small. I'm thinking that I will need some external method of increasing
    the current abilities for the version that lights 10 LEDs at once, is there a
    pre packaged unit that would take signal to turn on a high current load? Kind
    of like a solid state version of a relay board with a lot of inputs and outputs.




    --
    Chris W

    "They that can give up essential liberty
    to obtain a little temporary safety
    deserve neither liberty nor safety."
    -- Benjamin Franklin, 1759 Historical Review of Pennsylvania
     
  4. Hello,

    A bipolar transistor or FET or relay driver pack or led drivers etc. The
    micro side is very easy
    to program.

    Geoff...
     
  5. Jim Davis

    Jim Davis Guest

    A 74HC4017 decade counter has 10 outputs ,
    one output 25mA high at a time ,
    with max V+ of 6 VDC .
    Thus each 74HC4017 output can light 3 series LED's .
     
  6. Jim Davis

    Jim Davis Guest

    maybe 12 series LED's fed with 10 74HC4017 outputs
    and 10 NPN transistor switch's ?

    --+-->|--+-->|--+-->|--+-->|--+-->|--+--
    | |
    1of10 | |
    4017 | /
    OUT------+------------------|
    25mA \
    v
    |
    _____
    ___
    _
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-