Two timers -- one for 3 sec on and 10 sec off, another is 40 sec on and 20 min off

Discussion in 'General Electronics Chat' started by karas, Jun 25, 2016.

  1. karas

    Thread Starter Active Member

    Sep 8, 2011
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    I need to design timers has the following
    a-3 second on and 10 second off
    b-another timer has 40 seconds on and 20 minutes off
     
  2. Tonyr1084

    Active Member

    Sep 24, 2015
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    Try Arduino. You can program multiple timers and have them respond exactly the way you like.
     
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  3. Techno Tronix

    Member

    Jan 10, 2015
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    What about 555 Timer? I think Arduino will be very expensive.
     
  4. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    The TS doesn't need an arduino, he can use any microcontroller. PIC's made by Microchip are quite cheap even compared to the 555. If he has no experience with MCU's, I would suggest starting with the 12Fxxx or 12F1xxx series.

    Also, for those log intervals, he might be better off with a CMOS version of the 555, such as the LMC555 or TS555, if that is the way he goes.

    John
     
  5. EM Fields

    Member

    Jun 8, 2016
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    How accurate do they have to be?
     
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Even a CMOS verion of the 555 won't be good for consistent delays of 20 mins. A delay that long requires a very high resistor value and a high value electrolytic capacitor. The problem then is that the (temperature and age dependent) leakage current of the cap is comparable to the charging current via the resistor.
     
  7. Tonyr1084

    Active Member

    Sep 24, 2015
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    Perhaps it may take a 555 in combination with a counter - or even a divider / counter.

    [555] ---> [CD4013] ---> [CD4017]

    Since the 4013 is a dual D Type FF the slow timing of the 555 can be divided by 2 or 4 (using one or both FF's) then divide by 10. That way a more stable timing circuit (555) can be utilized. Using output 0 for the trigger point and using any one of the 1 - 9 outputs to reset the counter and FF's.

    But I know you want to set non-standard timing (3 on / 10 off) & (40sec on / 20min off). Using MY 555 system you can have 3 on 9 off, if that's usable to you, or 40sec on and 360sec off. (360 sec = 6 min). I'd have to use an additional 4017 if I wanted to extend the count.

    Using a micro controller seems a better approach (to me) be it Arduino or PICAXE or something else. I'm not practiced in anything other than the 555, 4013 & 4017 for counting. I'm guessing there's another chip out there that is a "Divide by N" that you can achieve numbers closer to what you want.
     
  8. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Let's see, PicKit3 (29.99 + $4.99 shipping) + PIC chip ($0.89) = $35.87
    Arduno pro mini (9.99 + 9.50 shipping) = $20.49

    So, Pic is not cheap. For the Pic, some type of pcb or breadboard will be needed. Everything can be soldered directly to the arduino pro mini board.
     
  9. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    If you want to take this thread off on a tangent and discuss the various costs associated with the different MCU's, perhaps that would best be done in a new -- your own -- thread.
    Here is a summary plus a little of what has been offered:

    1) A 555 + a counter
    2) A CMOS version of the 555 -- the LMC555 is specified to delays >20 seconds (http://www.ti.com/lit/ds/symlink/lmc555.pdf )
    3) A third, modified 555 with built-in decade counter will give deialys to > 1X10^5 seconds (http://www.customsiliconsolutions.com/downloads/Revised Standard products/CSS555C_Spec.pdf )
    4) Any one of many different microcontrollers, including PIC's

    What additional constructive recommendation(s) do you have for the TS?

    John
     
  10. crutschow

    Expert

    Mar 14, 2008
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    For the shorter periods you can use 555 timers and, for the longer time period, you can use a CD4060 circuit such as here.
     
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  11. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    I'd go with the 4060, or 4020, if an MCU isn't acceptable.
     
  12. Tonyr1084

    Active Member

    Sep 24, 2015
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    I like the 4060 diagram Crutschow linked in. Last year I built a 555 board simply for those times I needed a clocked source that had five selectable capacitances so I could choose several different periods of time. Depending on which cap switched into the circuit - the timer would run at differing rates. Switching two caps in at the same time (in parallel) would result in combinations, so I had more than just five selectable periods. I also included a chip carrier and wired it so I could put much larger or much smaller caps in to get more numerous periods. I did not know the 4060 would be so versatile. I may just build one of these to add to my work bench.

    Two thing I didn't understand in the diagram: The first is 'what's +Ve and -Ve'? Is this a split supply? Or is the negative lead (of say - a battery)? The second thing that has me confused is the setup table. Wouldn't a time period divided by (say; output 5 (pin 5) divides pin 7 by 2); wouldn't that be half the timing of pin 7? (or half the time period) Pin 3 would be 1/1024 of pin 7, NO?

    I hate building things that don't work. Worse yet, I hate building things that work but mine doesn't because I didn't understand something.
     
  13. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    It's not a split supply; it's just the two terminals of a single supply (battery).
    In the absence of a circuit description I don't follow the Setup table either.
    For the 4060, pins 9,10,11 are for generating the clock frequency f. The output at Q4 should be f/(2^4), that at Q5 should be f/(2^5), etc.
     
  14. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    +Ve and -Ve are the battery supplies pos neg,

    The time outputs are divided by two every time, so if the first output goes high after 10seconds, the next output takes 20 seconds,the third takes 40 seconds doubling each time etc..
     
  15. crutschow

    Expert

    Mar 14, 2008
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    If you notice in the table, each time range is basically a factor of 2 different from the adjacent values.
    If you want to make the time range easily selectable, you could use a single-pole, 10-throw rotary switch to connect the "range" wire to the desired output pin.
     
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