LED Flasher Circuit

Discussion in 'The Projects Forum' started by stvt, Nov 13, 2011.

  1. stvt

    Thread Starter New Member

    Nov 13, 2011
    2
    0
    I am looking for a circuit, possibly using the 556 timer, which will flash an led with two quick flashes then a pause, two quick flashes then a pause, etc.

    Ideally a circuit that I could easily change to select the number of flashes (eg change from two quick flashes to three quick flashes).

    Any help would be much appreciated.
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    Welcome to AAC.

    This is doable, a simple oscillator where the pause is where the signal is low.

    This signal would go into the second oscillator, which would be the actual flasher.

    You need to get the timing you need though.
     
  3. stvt

    Thread Starter New Member

    Nov 13, 2011
    2
    0
    The timing would be something like:

    on for 0.25s, off for 0.25s, on for 0.25s, off for 1.0s, etc.

    I can then fine tune it by varying the values of the components.
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,093
    3,032
    You could route the timer into 4017 counter, and take your output by ORing the 0 and 2 outputs. Reset on 5 or 6, or however long you want to have off in between flashes.

    On reset, the 0 would come on, lighting your LED. It would go off on clock tick 1. On click 2, the LED would come on again. On ticks 3 and 4 (or up to 9), it would remain off. When the clock reaches whichever pin you choose for the reset, 0 will go high again and the sequence starts over.
     
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