22Hr on 2Hr Off Timer

Discussion in 'General Electronics Chat' started by skj, Jun 12, 2015.

  1. skj

    Thread Starter Member

    May 20, 2010
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    I want to build a timer which should trigger a relay ON for 22Hrs then OFF for2 Hrs,This cycle should continue till a reset is applied,Any Idea Please?

    Thanks
     
  2. crutschow

    Expert

    Mar 14, 2008
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    Why not just use a commercial wall timer such as this to control the relay?
     
  3. dl324

    Distinguished Member

    Mar 30, 2015
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    What is your application?

    22 hours is a long time for a simple 555-type timer circuit.
     
  4. dl324

    Distinguished Member

    Mar 30, 2015
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    That was my thought too, but the OP didn't give me enough info to suggest it:confused:

    I like to use computer controlled X10 modules for line powered timed applications.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,553
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    If northern US or Canada, you can get a block heater timer, cheap, they handle a heater load and come with input output cord.
    Max.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    I've designed quite a few of them, but off the shelf is always cheaper.
     
  7. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    I have several of these I use to control battery chargers, etc. Work well, easy to program.
     
  8. skj

    Thread Starter Member

    May 20, 2010
    22
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    I want to control a motor supposed to be ON for 22 Hrs and then go to Rest for 2 Hrs. I drawn a circuit based on Ron J's Circuit Page and www.doctronics.co.uk (based on 4060B binary counter) these are Astable multi vibrator (22Hrs)and a Mono shot(2Hrs).but what i drawn is 22Hrs OFF and 2 Hrs ON. As we Power up the circuit astable multivibrator 4060B gets resetted and Relay picks up .As Pin3 (Astable Multivibrator) is initially zero triggering Monostable so 22 hrs cycle starts from a zero(falling edge pulse) ends with another falling edge pulse after 22Hrs .whereas I want 2hr Timer to start after 22Hrs.
    I am attaching present circuit drawing in PDF file
     
  9. crutschow

    Expert

    Mar 14, 2008
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    Do you need the 24 hours to be precisely timed to the time of day?
     
  10. skj

    Thread Starter Member

    May 20, 2010
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    No very precise timings are not needed approx 22Hrs ON and 2Hrs OFF will do
     
  11. crutschow

    Expert

    Mar 14, 2008
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    Then the 4060B circuits should do what you want if you don't want to use an off-the-shelf plug-in timer.
     
  12. dl324

    Distinguished Member

    Mar 30, 2015
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    That schematic is a good example of how not to draw a schematic. Personally, I wouldn't use one of the outputs of a flip flop to drive that significant of a load.

    Since you want 22 hours on and 2 hours off, you can use the unused NAND gate to invert the output of U1A and get back some noise immunity.
     
  13. skj

    Thread Starter Member

    May 20, 2010
    22
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    Thanks for your valuable suggestion, I will remove LD5 from Pin3 Of U1A and follow the change suggested by you to invert U1A output, will report back after testing the changes.
     
  14. skj

    Thread Starter Member

    May 20, 2010
    22
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    I have tested the circuit by inverting U1A out put and putting a NP capacitor between Pin3 4060A and Pin1 4011A .Result is that always 2Hr cycle comes first , Relay either is picked up or dropped depending whether U1A Output is inverted or not inverted Requirement is 22Hr cycle should start first.
     
  15. dl324

    Distinguished Member

    Mar 30, 2015
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    Circuit may require more modifications than I thought; I only gave it a cursory analysis...

    Do you have documentation describing circuit operation? Did it tell you to AC couple the output from U2 to U1A?

    Can you confirm the values of the R and C for both counters? R32+RV2=? R6+RV1=?
     
  16. skj

    Thread Starter Member

    May 20, 2010
    22
    0
    1) Circuit designed is based on two different ideas i.e.4060B as Astable and 4060B as monostable ,hence documentation is individually available Ron J's Circuit Page and www.doctronics.co.uk
    without coupled capacitor RS flipflop does not work therefore Pin1 U1A is connected through NP Cap.

    2) R32+RV2= 1Mf,190k :: R6+RV1= 11Mf ,190k

    3) A different idea has come to my mind. A basic block diagram is attached, this is not a schematic
    Explanation is given in attached block diagram itself, please comment whether this can work?
     
  17. dl324

    Distinguished Member

    Mar 30, 2015
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    I went to the website you referenced, and I wasn't inclined to spend time searching for the timer you're using. A link to the page with the information would have been more helpful...

    I think the attached schematic is a more straightforward (IMO :)) solution. It uses a single CD4060 as an hour counter, a couple flip flops (one to replace the missing Q11 output), and some AND gates to decode the number of hours:
    22on2offTimer.jpg
    This circuit gives you some flexibility in on/off times without having to re-tune the oscillator.

    Disclaimer: I don't have any CD4060 on hand so I didn't breadboard; I don't use simulators. I've walked through the design several times and didn't notice any problems...
     
    Last edited: Jun 20, 2015
    absf likes this.
  18. skj

    Thread Starter Member

    May 20, 2010
    22
    0
    Thanks for the efforts you put in, I will study the circuit suggested by you and bread board it.
    Thanks.
     
  19. skj

    Thread Starter Member

    May 20, 2010
    22
    0
    I have built the circuit using two 4060 counters these counters are reasonably cheaper.Circuit is working as desired. Any On Off timing can be set by changing RV2 and RV3 pots. I am uploading this circuit
     
  20. dl324

    Distinguished Member

    Mar 30, 2015
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    Glad you have it working, albeit with a brute force solution.

    Other than CD4060 being surprisingly inexpensive; was there a problem with the schematic I suggested?

    Now that you have a working solution, I have some constructive feedback on your schematic drawing style.

    1. You are using an ancient nomenclature for capacitance that might be interpreted as a much larger capacitance.
    2. Be consistent in the way you draw circuit elements (e.g. the orientation of LEDs and their current limiting resistors, use either 'K' or 'k' for kilo ohms but not both, label all components).
    3. Remove unnecessary bends and connection dots; be consistent with connection dot usage, as used on pin 9 of the 4060's.
    4. Avoid loading outputs that are critical for correct operation.
    5. C27/R57 forms a differentiator and it's more typical to draw the capacitor horizontal; though, paradoxically, when used as a power on reset it's drawn as you drew C24/R56.
    6. You appear to have a stylized way of drawing series caps, I don't care for it because I kept finding myself trying to understand why they were drawn that way.
    7. Since you only used 1 inverter, you could replace it with the transistor equivalent; excepting the case where the NAND was a spare gate. Why is it called Inverter2?
    8. R63 is unnecessary.
    9. D8 connection is sloppy.
    10. A supply voltage would be more useful than "HI" for calculating RC time constants.
    11. For complete circuits, clean up component labels so there are no gaps or document the gaps.
    12. Consolidate your notes in one place.

    Since I've critiqued your schematic, feel free to do likewise on mine...:)
     
    Last edited: Jul 3, 2015
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