555 & 4060 repeatable timer help

Discussion in 'The Projects Forum' started by nottortoise, Dec 15, 2015.

  1. nottortoise

    Thread Starter New Member

    Dec 14, 2015
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    Hello,

    I am new-ish to the game and I have run into some trouble trying to set up a timer circuit.

    My goal is to have a high output duration of around 20 seconds every 4 or 6 hours. Accuracy is not a concern for me as I am using this circuit to empty a dog bowl.

    At the moment I have NE555P, CD4017BEE4, CD4020BEE4 & CD4060BEE4 in my draw. I think that the 4060 will serve the purpose, though i'm not really sure, I am a bit lost looking through all of the data online. There seems to be a million different ways to do this and I just can't get my head around it.

    This is my current set up (about 11 seconds high at the moment)
    Timer.jpg

    Any help would be greatly appreciated.

    P.S. I also have the MSP430 launchpad with some additional IC's. I intended to use this, however the programming is entirely over my head also. I am thinking that using analogue IC's to start with would be a good base to work from when I start to learn programming down the track.
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    I have designed quite a few repeatable timers. Exactly what are you trying to do? There is a good chance I have something I've already drawn in my library that does what you want.
     
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  3. nottortoise

    Thread Starter New Member

    Dec 14, 2015
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    I am trying to set up a a motorised drain valve on a dogs water bowl, the bowl has a float valve so that it refills itself when the water level goes down.

    At the moment I have it functioning so that when I press the momentary switch, it drains for 11-ish seconds. This works well, though, I need to increase the time it's open to more like 20 seconds, and I would like for it to do this by itself at a certain interval.

    I'm looking at a circuit that will supply me with a pin that will go high every 4 - 6 hours for 20 or so seconds. This doesn't need to be adjustable or very accurate.

    I am using a 12v regulated power supply rated to 1.5 amps.
    Thanks in advance
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    To get 22 seconds, add a second 100k resistor in series with the existing 100k ohm resistor. If you need closer to 20, just replace the existing 100k with a 180k (don't add anything in series in this case).



    I'll think about your 6 hour delay cycle. Do you have a second 555 or anything else in your stockroom?
     
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  5. nottortoise

    Thread Starter New Member

    Dec 14, 2015
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    I have another 49 555s
     
  6. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Here is your CD4060 circuit. Shown is one hour. All times can be increased by 5x by changing C1 to 1uF. Now you have aa 5 hour timer that keeps repeating.

    The only thing left is to couple the two together with a capacitor. A cap is necessary, otherwise you will have water running for 2.5 hours while the 4060 is low, plus 20 seconds.

    [​IMG]
     
    Last edited: Dec 16, 2015
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  7. nottortoise

    Thread Starter New Member

    Dec 14, 2015
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    Thanks for the help. I will have to look when I get home, my phone isn't showing a file or a pic
     
  8. nottortoise

    Thread Starter New Member

    Dec 14, 2015
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    All good. Showing it now. So If i change the cap and then put another cap in line between the 4060 pin 13 to the 555s pin 2 instead of the momentary switch, that should do the job? What size cap inline?
     
  9. crutschow

    Expert

    Mar 14, 2008
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    Try a 0.1μF capacitor.
    Note that the 555 will trigger when the output of the CD4060 goes low after it's gone high. This does not affect the repeat time between triggers.
    Also note that if you don't reset the CD4060 to a known state at power-on, then the time to the first trigger can be random.
     
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  10. Wendy

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    Mar 24, 2008
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    OK, this was the thread I came with something very similar...

    http://forum.allaboutcircuits.com/threads/timer-circuit-with-555-and-4060b.33015/page-3#post-207069

    This schematic is my base ...

    [​IMG]

    I like to doodle with electronics, used to do it a lot more.

    You want a relay that closes 20 seconds every 4-6 hours. I'll modify this circuit to do what you want, it will be much simpler since your specs are so loose.

    I'm averaging the cycle time to 5 hours give or take for general use. If you want a different time let me know.
     
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  11. nottortoise

    Thread Starter New Member

    Dec 14, 2015
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    Thanks for all of the help. I've since found that my on time needs to be more like 40 seconds, though that's no biggie. I read somewhere that I should not exceed 100uf for my 555. Is that true?
     
  12. Wendy

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    Mar 24, 2008
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    Not really. As you get into bigger capacitance it is possible that the minor imperfections of the capacitor may cause a malfunction, but I have used much larger with no problem.
     
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  13. nottortoise

    Thread Starter New Member

    Dec 14, 2015
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    That's a big help knowing about the higher capacitance limit. Any chance that I can substitute a 1μF for a 0.1μF? (not the one for 555 timing)
     
  14. Wendy

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    OK, finished the modification. The base time is 4.5 Hours, if this is OK you can eliminate R3. You can also increase R2 to match your ideal time.

    4060 555 timer 2.png

    If you have a question about a specific part use the part number I gave. I'm pretty OCD about doing it.

    Timer duration: 4.5 Hours
    On time :40 seconds.
     
    Last edited: Dec 16, 2015
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  15. Wendy

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    Post #9 made a good point, which I did not incorporate. I am going to sleep, but if you want I'll add a power up reset tomorrow,
     
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  16. nottortoise

    Thread Starter New Member

    Dec 14, 2015
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    Thanks for all the effort.

    Just a few questions,

    What's the wire going between R2 & R3?

    I tried simulating this on Yenka, it is the only program that I have access to. I include 2 images, each in different states around the oscillator on the 4060. (Yenka simulates this chip without VCC or GND.) Pin 9 - OO, pin 10 - OI, pin 11 - top left, pin 12 - R.
    AAC Wendy Circuit 1.jpg AAC Wendy Circuit 2.jpg
    All seems good (nothing failing on the simulation), though rather then waiting for the circuit to cycle, I tried taking my 555 trigger from pin 7 on the 4060 as I saw this 2 cycle from LOW to HIGH much sooner than pin 2 (pin 13 Yenka). However while this moved from LOW/HIGH/LOW, nothing happened from the 555. Any ideas?

    Thanks for all of the help so far
     
  17. nottortoise

    Thread Starter New Member

    Dec 14, 2015
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    Sorry, just noticed my cap values are 100µf not 47µf
     
  18. GopherT

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    Nov 23, 2012
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    There are some settings in your simulator that may need to be adjusted. The pulse from the 4060 is very fast compared to everything else that is happening. If your simulator is set to anything below 100,000 updates per virtual second, it may be missed. The default may be as low as 256 updates per second.

    image.jpg
     
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  19. nottortoise

    Thread Starter New Member

    Dec 14, 2015
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    The default is 50 ms (I'm guessing milliseconds), the lowest I could set it for is 0.01 ms. I think that would make it 10,000 times per second as a maximum for the program. Is this a big issue?
     
  20. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Any event shorter than 0.0001 seconds will not show up. Run it and check. 0.1uF should be longer than that. However, in real life, your 4060 may not have enough current sinking capacity to pull such a big capacitor below Vcc/3 which is required to trigger the 555 timer. You will have to build it and check. Or, look at projects that other people have built to see how they did the capacitive link between the two devices.
     
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