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¿1 Hz oscillator?

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by LApprenti Sorcier, Oct 21, 2003.

  1. LApprenti Sorcier

    LApprenti Sorcier New Member

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    Some of you migh have seen the posts on "Digital clock" I've been wondering what's teh easiest way of generating a precise 1 Hz frequency for the clock.

    An idea I heard of is dividing by 60 the AC frequency and using that instead. (or some adaptation, but the idea remains to get the pulses from it).

    Any ideas?

    Also, ca anyone tell me an easy way to make one with a crystal, hopefully, very much power-efficient. (I'm planning to run another one on batteries... )

    Thanks a lot!
     
  2. Optikon

    Optikon New Member

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    build a 32.768kHz oscillator circuit that can output CMOS or TTL levels. You can buy the complete unit or build one using a 32k crystal. Once you have that, run it into a digital divider circuit that will divide it by (2^15) then output that result and you will have a clean, precise 1Hz clock.

    The 60Hz method can work (using zero crossing detectors) but since you didnt mention how "precise" you need it, the crystal is the way to go. BTW, you dont need 32k, you could use any value that is divisible by a power of 2.

    I think the power company regulates the 60Hz to something like 60Hz +/- 0.001 Hz.. maybe that is good enough for you - I dont know.
     
  3. laroche73

    laroche73 New Member

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    60Hz frequency

    I did a search on power line frequency variations recently and came across the following:

    http://www.ornl.gov/ORNL/BTC/Restructuring/ORNLTM200341.pdf

    The article indicates the power line frequency in the U.S. is normally kept to within +/- 0.05Hz of 60Hz.

    A 32Khz crystal along with a CD4060B or CD4020B 14-stage divider will give you a 0.5 second output. The 4060 includes an on-chip oscillator. 32Khz is a good choice for a portable timebase, very low power consumption, cheap & good accuracy.
     
  4. dave

    Dave New Member

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  5. john1

    john1 Active Member

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    Hi L'Apprenti Sorcier,

    what's teh easiest way of generating a precise 1 Hz
    frequency for the clock.


    The easiest way is to get the movement from a discarded
    quartz clock.
    They can be found easily.
    The 1 Hz signal is precise.

    If you care to pick away the plastic case and cogs,
    the actual unit is quite small.

    Don't forget its 1.5v and uses very little current.
    I doubt if you will find an easier way,
    or a more economical way.

    John :)
     
  6. LApprenti Sorcier

    LApprenti Sorcier New Member

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    thank you all

    Thank you very much.

    I've chosen to discard the AC input, for the reasons you told me and besides, if i'm already going for a portable one, there will be no disadvantage in using the same with the stationary.

    Does anyone know where can I find more information on the 4060? schematic/example circuit/power specs.? I've never worked with it before...

    About the quartz movement... How do i know what am I looking for inside the clock? Will any clock do?

    Thanks again!
     
  7. Phasor

    Phasor Member

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    Re: thank you all

    Here is the circuit to get a 2Hz clock signal, using the 4060. You will need to add a divide-by-2 on the end to get 1Hz (eg, flip-flop).
     

    Attached Files:

  8. LApprenti Sorcier

    LApprenti Sorcier New Member

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    IC 4060

    Any idea of where can I get a complete specification sheet on the 4060?
     
  9. LApprenti Sorcier

    LApprenti Sorcier New Member

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    power supply

    I've been wondering for how long would a common battery supply a circuit like the one drawn above... any idea?

    What would be the most efficient means of getting those 5V?
    How much current can a 7805 give me???

    Thanks!
     
  10. LApprenti Sorcier

    LApprenti Sorcier New Member

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    divide by two

    what's a common, energy efficient flip flop to divide the pulses by two?

    Thanks
     
  11. laroche73

    laroche73 New Member

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  12. LApprenti Sorcier

    LApprenti Sorcier New Member

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    Thanks!

    I'll try that..
     
  13. LApprenti Sorcier

    LApprenti Sorcier New Member

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    Does anyone have a diagram for the 4013 divider? what's the difference between that one and the 4017?

    I'm wondering how should i use it to divide by two?
     
  14. pebe

    pebe Member

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    You mention a 4017. If you have one you can use that as a divide-by-2.
    Connect the '2' output to Reset. When it counts, it will go 0 > 1 >2 which will rest it back to 0, So effectively it will count 0 > 1 > 0 > 1 etc. Take your output from either the 0 or the 1 to get the divide-by-2.
     
  15. 11flint

    11flint New Member

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    Many aplogies for replying to a vey old thread, but could someone tell me how to properly amplify the 1Hz signal coming out of the 4013 to about 3 to 4 volts? I built the circuit, but the output is a measly 160mV. Not enough to drive a decade counter.
     
  16. Hero999

    Hero999 Banned

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    If that's happening you're doing something wrong. The output voltage from this circuit should be more than enough to drive another CMOS circuit.

    Please post a schematic.
     
  17. colin55

    colin55 Well-Known Member

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    Buy a $5.00 clock mechanism from a $2.00 shop and use the chip and crystal.
     
  18. 11flint

    11flint New Member

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    This is how I setup the circuit (sorry for the sucky picture)

    [​IMG]

    Of course the relative pins on the 4013 are on 5v and ground.

    I'm feeding the outpout of the 4060 to "clock" on 4013, feeding D into Qbar, and taking output from Q.
     
  19. 11flint

    11flint New Member

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    The counter is a 74LS162PC, a ttl I think.
     
  20. Hero999

    Hero999 Banned

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    It's no surprise it's not working - you're trying to mix TTL with CMOS.
     
  21. 11flint

    11flint New Member

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    o you mean to say that the 4060 and 4013's are CMOS, and that's why they are not working with the TTL counters? OK, great, but regardless, why is my output voltage so low on the 4013? Or is that not a problem if I were to use CMOS counters?
     

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