40110 counter build - weird display problem

Discussion in 'The Projects Forum' started by fugoohomer, Apr 1, 2014.

  1. fugoohomer

    Thread Starter New Member

    Apr 1, 2014
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    0
    Hello there experts,
    I have a question regarding my 2 digit up/down counter using 40110 IC and NE556

    I have used a 5 metre roll of 12volt led strips to make my 7 segment number display. Each segment is a 6 led/10cm strip (needed 30cm high numbers)
    Power is a 12v Battery ( the ones used for battery backup in alarm systems)

    I built the circuit on a breadboard tested it and counting is perfect.

    I then built the circuit with IC Sockets on a Vero board, counting is again perfect however the segments do not turn off fully during counting.
    ie the "off" segments are dimmly lit.

    I transfer the 40110, 556 ICs and the 7 segment display back to the breadboard the segments turn off completely. So I transfer the 40110, 556 and 7 segment display back to the vero board and the segments again dont turn off completely.

    Is there any reason why this is happening? I'm stumped
    :confused:
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,740
    759
    can you show the schema of the vero board you built.
     
  3. tshuck

    Well-Known Member

    Oct 18, 2012
    3,531
    675
    Make sure you don't have any floating inputs.

    I'll second the call for a schematic...
     
  4. fugoohomer

    Thread Starter New Member

    Apr 1, 2014
    3
    0
    I built the counter off the following circuit diagram (40110 counter circuit.jpg)

    Circuit built onto Vero Brd (40110 Counter - Vero brd.jpg/40110 Counter - Vero brd under.jpg)
    It is replicated exactly off my breadboard build.

    If the bread board had floating inputs same as the Vero board I would of thought it would show the same symptoms, yet it doesn't.
     
  5. MrChips

    Moderator

    Oct 2, 2009
    12,418
    3,355
    When you cut Veroboard into smaller pieces use a fine file and remove any copper burrs at the edges. Also go over all the cut tracks and solder joints with a magnifying glass and make sure there are no unwanted shorts.
     
  6. ScottWang

    Moderator

    Aug 23, 2012
    4,850
    767
    measure each pin of ic from parts side to the solder side.
     
  7. fugoohomer

    Thread Starter New Member

    Apr 1, 2014
    3
    0
    I measured with multimeter, each output pin is not shorted against the next.

    So I tested my 2nd Vero board build, ( i need 2 separate counters ) and there is no problem with the segments being off completely.

    The only thing i can see is the 2nd vero board build does not have as much solder as the first. (the 1st build i was using a different soldering iron with a thicker tip)

    Could the amount of solder between each pin be causing some type of capacitance effect ?
     
  8. MrChips

    Moderator

    Oct 2, 2009
    12,418
    3,355
    No. Not in your case.

    Check all your GND connections.
     
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