How to run a 4017 (Decade Counter) once and then stop?

Discussion in 'General Electronics Chat' started by Ayush Modi, Jun 27, 2015.

  1. Ayush Modi

    Thread Starter New Member

    Jun 27, 2015
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    I would like to run a Decade counter circuit (controlled by a astable circuit) once and then stop (see picture below).
    circuit4.PNG
    This circuit does intend what I try to do. But it keeps looping, so I need a method to turn off that astable, or somehow short-circuit it after the LED flashes.

    Thank you in advance.
     
  2. #12

    Expert

    Nov 30, 2010
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    Have Q10 ground pin 4 with an npn transistor?

    Depends on the restart procedure.
    I told you how to stop it. How do you want to restart it?
     
  3. Reloadron

    Active Member

    Jan 15, 2015
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    Sounds like you want a count to N and halt where N is Q9 out. You could use similar to the attached drawing using a SPDT switch for run and reset.

    4017 Count to N and halt.png

    The drawing is a partial so keep that in mind. For the 4017 to count the enable input (clock enable) needs to be low, your drawing does not reflect that? When the enable input goes high the clock is inhibited and the count stops. Since the 4017 outputs sequentially go high they are normally low. Do not leave the enable pin floating as in your drawing. Read the Data Sheet.

    Another option is as #12 suggested. Just a matter of exactly what you want to do and how you want to go about it.

    Ron
     
  4. korchoi

    Member

    Jun 5, 2015
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    I would recommend using Q9 as an input to some actuator that would stop the chip.Maybe block the clock.
    But Reloadron beat me to it.
     
  5. #12

    Expert

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    So did I.:p

    That means after Q9 has gone low...like when Q10 goes high.

    Edit: There is no Q10 as shown in post #1. Using Q9 for the shut-off will work if the LED is moved to Q8
     
    Last edited: Jun 27, 2015
  6. Reloadron

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    Where is Q10? You lost me on this Q10. Granted, I get lost easily.

    Ron
     
  7. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Just put a diode in series with a 1k resistor from Q9 to PIN6 of the 555. The 555 will stop immediately and start running again when you reset the 4017.
     
  8. #12

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    According to the picture in post #1
    Q10 is on the bottom right side of the 4017B chip.
    According to your drawing, there is no Q10, Neo.
    Did I just follow a noob into a dark alley?
     
  9. #12

    Expert

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    Yes, I did. :oops:

    Still, moving the LED to Q8 and using Q9 for the shut-off would work.
    (Notice how much easier this gets when a datasheet is posted.)
     
    Last edited: Jun 27, 2015
  10. Ayush Modi

    Thread Starter New Member

    Jun 27, 2015
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    Hmm, is this is for the decade counter or the 555 timer?
     
  11. Ayush Modi

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    Jun 27, 2015
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    circuit5.PNG
    Do you mean this?
     
  12. #12

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    Yes. Pin 4 is the disable pin for the 555 and Q is an output pin on the 4017 chip. There was some confusion about which Q is available because your drawing showed a pin called, "Q10". There is no Q10 on that chip.
     
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  13. Reloadron

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    Jan 15, 2015
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    I meant it as I drew it. Pictures don't work well for me, getting a headache following wires is not entertaining. You can configure the 4017 in a few ways, among them is count to N and halt or count to N and recycle. I gave you a sample of count to N and halt and suggested you read and study the data sheet. Also per your original drawing there is no Q10. Since you did not label pin numbers I can only assume Q10 is actually the CO pin 9 the Carry or Carry Out. I suggest the data sheet to understand what the Carry pin actually does and what the signal looks like, it's low for 5 counts and high for 5 counts. What is the transistor doing in the above circuit if that is a transistor? Driving the LED? I don't see a series resistor for the LED I don't see a base resistor for the transistor and finally I don't see any specifications for the LED? What is the battery voltage? Transistor part number would be nice.

    Ron
     
  14. GopherT

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    Nov 23, 2012
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    Jeez, did you run out of Folger's this morning?
     
  15. Reloadron

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    Jan 15, 2015
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    :) Actually I am in a good mood this morning. Well, we could do better for weather but if I recall your location correctly you know that. I guess I just wish people would at least make a good attempt at using or referencing data sheets and post schematics. Sorry if I did come across a little mean spirited. Now, with coffee done time to look forward to a few hard ciders. :)

    Ron
     
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  16. Ayush Modi

    Thread Starter New Member

    Jun 27, 2015
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    Thank you, this works!
     
  17. Ayush Modi

    Thread Starter New Member

    Jun 27, 2015
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    Ok, there's one last problem (hopefully).
    Does anyone know how I can send a permanent charge (like from the battery). After, I receive a short pulse.
    I thought of transistors but they would only do it as long as the pulse lasts.
    Maybe the pulse triggering a switch?
    Any suggestions?
     
    Last edited: Jun 28, 2015
  18. #12

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    It's called a latch. It can be as simple as an SCR. Once you start an SCR it won't stop until the current through it approaches zero.
     
  19. GopherT

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    Q9 of the decade counter should stay on so you can drive a MOSFET transistor from that pin.
     
  20. #12

    Expert

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    Oh. Did he mean, "with this timer circuit"?
    Well, an SCR would probably work.
     
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