Astable Multivibrator

Discussion in 'The Projects Forum' started by Coat53y, Aug 15, 2013.

  1. Coat53y

    Thread Starter New Member

    Aug 13, 2013
    2
    0
    Hi guys,

    I have an astable multivibrator with a 555 timer and at the minute it runs through a sequence, from the circuit board there is a 12v power cable and then 2 seperate banks of 3 sets of 2 leds.
    the sequence is as follows:
    flash right twice-flash left twice
    flash left and right together 3 times
    speed up-slow down
    loop to beginning
    all i want it to do is flash left twice then right twice then back to left twice then back to right twice in a loop.
    i have uploaded a picture of the circuit board, hope you can help.
    thanks
    steve
     
  2. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    This works better if you ask a question.

    Schematic is always a plus.
     
  3. Coat53y

    Thread Starter New Member

    Aug 13, 2013
    2
    0
    sorry bountyhunter,
    the question is is there anything i can add or remove from the board to make it flash left twice and flash right twice instead of running in a sequence? I wouldnt know where to start in drawing a schematic hence the pictures
    regards
    steve
     
  4. Shagas

    Active Member

    May 13, 2013
    802
    74
    For someone to advise how to modify a circuit they should see the circuit first.
    You already got one. It's on that breadboard. You should reverse engineer it first :look at the components and the traces and draw up a schematic from them .
    The someone will look at it and give a suggestion .
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,090
    3,027
    Are you sure there's not more to the circuit somewhere? That's an awfully complex behavior for such a simple PCB.
     
  6. absf

    Senior Member

    Dec 29, 2010
    1,490
    371
    I dont think IC1 is a 555. A 555 would not be able to flash led in such a complex pattern. I'd guess is it is a 12Fxxx PIC or ATtinyxx and IC2 is a 78L05.

    Allen
     
  7. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,869
    1,393
    Agreed.

    @Coat53Y,

    Look at the 8-pin IC, and post the letters and numbers you see on the top. Of course, if it is a microcontroller, there's no (easy) way to reprogram it because (a.) it's soldered in the PCB, and (b.) you probably don't have a programmer. :(
     
    Last edited: Aug 15, 2013
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