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Help needed on designing a circuit for a digital clock (A level project)

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by MutantNoodles, Feb 28, 2010.

  1. mbarazeen

    mbarazeen Member

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    i meant the pins, it need a shift by one bit lower.ie if one pin of AND is conncted to Q6 it has to be connected to Q5 and so on.
     
  2. MutantNoodles

    MutantNoodles New Member

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    so like this?
    just a final check before i develop the pcb.
     

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  3. MutantNoodles

    MutantNoodles New Member

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    and to set the time, i was going to have 2 push to make buttons, one for the minutes, and one for the hours, where you flick a dpdt switch to switch from the input of the 1 min time base to the push to make switches. The switches, each time when pressed allow currnt to flow to the clock pin of the first 4017, but i dont think this is going to work, because i have been playing with the circuit.
    Is there a way to do it?
     
  4. dave

    Dave New Member

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  5. MutantNoodles

    MutantNoodles New Member

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    plese reply, i have to finish it by 3 hours time
     
  6. mbarazeen

    mbarazeen Member

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    use a OR gate at input of Min and hour counters seperately. ie: you are adding another input for both. then use a micro switch for both circuit inputs seperately to give a voltage high when the switch is pressed. use capacitor and resistor to fiter any noice and normally (when switch is not pressed) to have it to ground.
     
  7. MutantNoodles

    MutantNoodles New Member

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    the led's change every 25 seconds. (average)
    and for some reason the clock pin of the first 4017, wont change the leds? so i found out how frequently the pulses are by connecting the pulse out of the time base to the second 4017 (of the 6x10 matrix)

    i thought this time base was right? its not 1 minute pulses
     
  8. MutantNoodles

    MutantNoodles New Member

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    and when you say have a capacitor and resistor connected, how?
     
  9. MutantNoodles

    MutantNoodles New Member

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    yeah the circuit produces 6 pulses every 2.5 minutes
     
  10. MutantNoodles

    MutantNoodles New Member

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    and i have switched the chips around, but the first position wont change due to anything in its clock pin

    *have now fixed the problem

    though it still is changing time too quickly
     
    Last edited: Apr 27, 2010
  11. mbarazeen

    mbarazeen Member

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    if you have an oscilloscope you can check it easily by checking correct 200Hz. then check the states.
    did you use the right crystal?
    whats your AND IC? which PCB did u use as final?
    any how if you have made anything wrong, still its not hard to correct it since, its the matter of changing some pins of 2nd 4060.
     
  12. MutantNoodles

    MutantNoodles New Member

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    i used this sircuit and i used the 74hc11, 3.2768mhz crystal
    i dont have an ocilloscope :(
     

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  13. mbarazeen

    mbarazeen Member

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    did you etch the PCB? or you just wired? what i suspect is that you have made some connection wrong. make sure the pins 7,5,4,14,13,15 &2 are the only out puts connected to AND gates.
     
  14. MutantNoodles

    MutantNoodles New Member

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    yes they are all the right ones, and i etched the pcb

    are you sure you told me the righ tpins? maybe you said one pin wrongly, or miscalculated it?
     
  15. MutantNoodles

    MutantNoodles New Member

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    and on the first 4060 why is a capacitor attached to the reset pin?
     
  16. mbarazeen

    mbarazeen Member

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    ok i will tell how it will come,
    you have to divide by 12,000 in binary it is 0 1 0 1 1 1 0 1 1 1 0 0 0 0 0
    so its like this........................................... Q14 Q13 Q12 Q11 Q10 Q9 Q8 Q7 Q6 Q5 Q4 Q3 Q2 Q1 Q0

    i took it as above, if i have confused with this then Q0 is not correct. I THINK MY DIAGRAM IS CORRECT. but i asked you to change it, so just wire it again as it is on the diagram, ie connect pins 5,4,6,13,15,1,3

    sorry for any inconvenience
     
  17. mbarazeen

    mbarazeen Member

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    capacitor is on the GND wire, that is going through pin 12(reset) in another word reset is connected to GND.
     
  18. MutantNoodles

    MutantNoodles New Member

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    okay so is what you said correct then? because i am going to have to remove soem copper tracks and rejoin pins, i dont want to do that for it to be wrong, are you sure?
     
  19. mbarazeen

    mbarazeen Member

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    you have to remove only 3 connections,
    cut pin7 and connect it to 6
    cut pin 2 and connect it to 1
    cut pin 14 and connect it to 3

    hope it will work this time.

    Edit: i remember the timing diagram and its ok this time, if the input to 2nd 4060 is 200 Hz then without any doubt you must get a pulse every 1min. once you finish it give a feed back
     
    Last edited: Apr 27, 2010
  20. MutantNoodles

    MutantNoodles New Member

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    what do you mean? could you maybe post a quick sketch?

    and it works, but now it is about 54 seconds before next pulse
    maybe because instead of 15 pf capacitors with the crystal i used 22 pf?
     
  21. MutantNoodles

    MutantNoodles New Member

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    yeah the 'minutes' are about 5-4 seconds short, maybe it was the quality of the crystal
    i might try find a better quality crystal, and see if that helps
     

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