Electronic dice multisim troubleshooting

Discussion in 'The Projects Forum' started by kkoniecki, Dec 4, 2013.

  1. kkoniecki

    Thread Starter New Member

    Dec 4, 2013
    8
    0
    I have built a schematic on multisim for the required dice experiment I have to perform tomorrow. As I hold the switch the display seems to be switching between numbers but as I let go, the number disappears. Any idea how to fix this? I followed the schematic attached and my multisim is attached also. If youd like to see the file or any deeper questions plz post here or e-mail me at rockstarlivee@yahoo.com thx!
     
    Last edited: Dec 4, 2013
  2. kkoniecki

    Thread Starter New Member

    Dec 4, 2013
    8
    0
    I'm very much lost, the number just keeps jumping and disappearing doesnt stop or act as it should.
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,014
    3,234
    You need to add a 10k pulldown resistor from pin 14 on the 4017 to ground. Otherwise the pin is floating when the switch is open and CMOS circuits must never have any floating inputs.

    Why are you using a decade counter which requires all those diodes for decoding. You could use a 4026 counter instead which directly drives a 7-segment display, so you wouldn't need the 4511 either.
     
  4. kkoniecki

    Thread Starter New Member

    Dec 4, 2013
    8
    0
    I added the resistor and uploaded a updated photo. I also wanted to show you the 7 segment display i'm using, i feel as its not the proper one. The display is jumping all over the place as I close the switch and still will not show a number...
     
  5. kkoniecki

    Thread Starter New Member

    Dec 4, 2013
    8
    0
    I'm using these parts because I have them available to build the actual circuit on a board.
     
  6. kkoniecki

    Thread Starter New Member

    Dec 4, 2013
    8
    0
    Should I adjust my capacitor, voltage, resistors? I have no idea why this is happening
     
  7. crutschow

    Expert

    Mar 14, 2008
    13,014
    3,234
    You have the same floating input problem with the 4511. You need a 10k resistor on each input to ground to pull the input low when all diode inputs are low. Otherwise the input is floating. An open on a CMOS input is not logic low.
     
  8. kkoniecki

    Thread Starter New Member

    Dec 4, 2013
    8
    0
    Ok so i did the two 10k resistors and I added a capacitor to the CON of 555 timer. the display is still jumping around and wont stop at a number. Do I need resistors between the 4511 and Display? I tried it didnt do anything
     
    • sd3.PNG
      sd3.PNG
      File size:
      49.8 KB
      Views:
      39
  9. kkoniecki

    Thread Starter New Member

    Dec 4, 2013
    8
    0
    I appreciate your help a lot, ive been trying to construct this for 3 days NONSTOP
     
  10. kkoniecki

    Thread Starter New Member

    Dec 4, 2013
    8
    0
    Just constructed this circuit....and like all the others...doesnt work...i have no idea what I'm doing wrong. Nothing is working and I need a multisim/hard copy by tomorrow...wow this sucks
     
    • sdf.PNG
      sdf.PNG
      File size:
      43.9 KB
      Views:
      48
    • rge.PNG
      rge.PNG
      File size:
      147.2 KB
      Views:
      49
  11. crutschow

    Expert

    Mar 14, 2008
    13,014
    3,234
    Read my previous post. You need a resistor on all inputs that are driven by the diodes.
     
    Last edited: Dec 4, 2013
  12. absf

    Senior Member

    Dec 29, 2010
    1,492
    372
    The problem is due to that there is only one resistor R2 330R for the 7-segment LED. When more than one segment is lighted, the voltage drop across R2 is too great that all the segments would not have enough voltage to get lighted.

    I simulated the original 4511 circuit with 7 330R resistors and it worked. But adding 10K resistors to the inputs of 4017 and 4511 (as advised by crutschow) to prevent them from floating is a good practice when playing with electronics. This would prevent other unexpected problems in future.

    I attached the simulation I did in proteus..... as I dont have multisim in my PC.

    Allen
     
    Last edited: Dec 4, 2013
Loading...