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Urgent Help Please Circuit Design 555 Cd4017

Discussion in 'General Electronics Chat' started by Keshin, Dec 17, 2015.

  1. spec

    spec Well-Known Member Most Helpful Member

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    :happy:

    For the time being leave the 555 discharge pin unconnected
     
  2. Keshin

    Keshin Member

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    so do i just solder this in spot of the pot?
     
  3. spec

    spec Well-Known Member Most Helpful Member

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    Yes
     
  4. dave

    Dave New Member

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  5. Keshin

    Keshin Member

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    ok all soldered in, is there anything i should check or should i just plug it in now?
     
  6. spec

    spec Well-Known Member Most Helpful Member

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    If pin 7 of the 555 is still disconnected from the rest of the circuit and the temporary wire from pin 3 of the 555 has been removed, yes.
    After turning on, monitor the voltage at pin 3 of the 555, with the common lead of your multimeter (set to 20V) connected to the OV supply rail.
    Th meter shoul show around 0V for around 1 second, then around 6V for one second and so on.

    Fingers Xed
     
  7. Keshin

    Keshin Member

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    doesnt seem right heres a video so you can see
     
  8. spec

    spec Well-Known Member Most Helpful Member

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    Like video- no music?

    If wire is disconnected as I defined. the input pin to the counter should be up at 6V, so that is right.

    The rest seems to be OK.

    I have just rechecked the calculations and the timing should be 1 second @ 6V followed by 1 second at oV at pin 3 of the 555.

    Is the 10uF capacitor definately 10uF. Is it the right way around?

    Connect the meter set to 20V to the top of the capacitor with the common lead connected to 0V.

    Then watch the meter for some time, the voltage should be going up and then down between 2V and 4V. See how long it takes to reach 4V and then down to 2V.
     
    Last edited: Dec 19, 2015
  9. zahwi

    zahwi Member

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    Your video shows the classic problem with the 4017. It is a ripple counter and it counts properly only when it gets clean input. Try 47pF to 470pF from pin 14 to ground, or 470K to 2.2M resistor in series to pin 14.
     
  10. Keshin

    Keshin Member

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    thanks but at this stage i havent even got the 4017 tied into pin 14, problem is still in the 555 area
     
  11. Keshin

    Keshin Member

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    the 10 uf capacitor at the beginning of the circuit (where power and negative attach) is negative to negative + to +
    the 10 uf capacitor connected to pin 6 & 2 is connected + to 6&2 negative to common ground
    the 10 nf capacitor has no markings for polarity so i assumed it could go either way

    both the cap at the beginning of the circuit and pin 6&2 are marked "suntang 16v 10uf"
    the cap at the beginning of the circut is 0.08 and dropping
    the cap at 6&2 is 0.7 and dropping

    you did mean test with the red test meter lead on the top silver pad of the capacitor and the black test lead on 0v ?

    edit: sorry stand by while i test again this time with the battery connected
     
  12. spec

    spec Well-Known Member Most Helpful Member

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    Would moerators please delete this post
     
    Last edited: Dec 19, 2015
  13. spec

    spec Well-Known Member Most Helpful Member

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    :D:D:D
     
  14. Keshin

    Keshin Member

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    ok i have attached another video, after leaving circuit run for few mins that cap on 6&2 is bouncing between 0.22 and 0.17



    Edit: just so i understand as im not sure, but if 6v is applied to the reset pin 4 wouldn't that activate a constant reset?
     
  15. spec

    spec Well-Known Member Most Helpful Member

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    Is the initial cap the one across the power supply, because that always should have 6V on it.The circuit looks like it has no power: is your battery flat.

    What type of bat is it?
     
  16. Keshin

    Keshin Member

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    sealed lead acid 6v rechargable 1.3ah
    with circuit attached it shows 6.38 bouncing to 6.36
    pretty sure its still charged as its brand new only use has been doing this circuit

    edit: yes the initial cap is the one at the beginning across the battery input
     
  17. spec

    spec Well-Known Member Most Helpful Member

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    Is the supply line at the circuit up at 6V. can you measure between pin 1 and 8 of the 555 actually on the pins.

    Do you mean 1.3Ah, sounds low for a lead acid battery.
    .
     
    Last edited: Dec 19, 2015
  18. spec

    spec Well-Known Member Most Helpful Member

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    That reset input should be labeled 'Not Reset' in true logic terms. It resets on a nagative input- good question though
     
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  19. Keshin

    Keshin Member

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    supply line is at 6v

    and with negative test lead on actual pin on (on actual chip, on top of circuit where it enters the 555)
    and positive test lead on pin 8 (same way on actual chip)
    i am receiving 6 v

    and this is the battery
    [​IMG]
     
  20. spec

    spec Well-Known Member Most Helpful Member

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    Thanks for that.

    Hmm. I'm running out of ideas.The only thing left is the 10uF cap in the 555 timming. Have you got another capacitor of even use the one on the supply input. This is a vey simple circuit which normally works no problem.
     
  21. Keshin

    Keshin Member

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    i have more of those 10uf's i can swap them out
     

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