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Looking for a very cheap clock generator

Discussion in 'Electronic Basics' started by Ernst B, Oct 13, 2003.

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  1. Ernst B

    Ernst B Guest

    I am looking for a very cheap clock generator (e.g. as an input for a
    4020). I don't want to use an oscillator module, since that is too
    expensive for my application. Instead I'm thinking of a crystal, a
    cap, a transistor and some other simple stuff. Since I only have
    experience in digital IC design, I'm seeking for some advice how to
    build such a circuit.

    Thanks for your help in advance.

    Ernst.
     
  2. Is a NE555 still to expensive? I hope not. This standart timer is really
    easy of use and quite cheap. The only disadvantage about it is, that you
    can't receive a dutycycle by 1 (50% on and 50% off), but most of the cases,
    that doesn't matter.

    Dominic
     
  3. Cost shouldn't be a factor if this is a single project. And if
    it is a production item, you need to look at circuit board space
    of both scenarios, and the cost of all the components.

    Keep in mind that if you are building in quantity, price will go
    down.

    I'm not sure there is a big price difference between an oscillatorin a can
    and a crystal at the same frequency. If you choose the wrong frequency,
    cost may go up because it will have to be custom made, whether it is
    a crystal or complete oscillator. If you are't on a frequency where you
    can get cheap oscillators in cans, then you might want to look at the
    overall design and see if something can be changed to accomodate a common
    and cheap frequency.

    It might be cheaper, depending on the frequency, to go to a non-crystal
    oscillator. But you have to make sure that your design does not
    need the stability or even accuracy of a crystal. In production,
    if you have to adjust something to an exact frequency it may be more
    costly overall than a crystal (or crystal oscillator). But if you can
    get away with an RC oscillator, then you may find you don't need the
    divider, since it's easier (and often better) for an RC oscillator at
    a lower frequency. Note that many designs may use a crystal (discrete
    or in a prefabricated oscillator) because its cost even with a
    divider to get it down to the needed frequency is less than the cost
    and trouble of an RC oscillator (especially in a production setting),
    even if stability is not an issue.

    Michael
     
  4. Hi,

    How about using the 4060 instead as it has an internal
    oscillator circuit and is very similar to the 4020. All you need
    for an RC clock are 2-R and 1-C or, for the quartz version, 2-R,
    2-C and a crystal.


    Cheers - Joe
     
  5. Baphomet

    Baphomet Guest

    You might have to touch up the 470pf / 330pf capacitor values depending on
    xtal freq.
    http://www.militarymags.com/electronics/xtalosc.gif
     
  6. Baphomet

    Baphomet Guest

  7. CFoley1064

    CFoley1064 Guest

    I am looking for a very cheap clock generator (e.g. as an input for a
    Have you taken a look at ceramic resonators? They're cheaper than crystals,
    are as reliable, and have low frequency drift in comparison with anything else
    except crystals. If you want a "cookbook" design, look at the datasheet for a
    Panasonic general purpose ceramic resonator below. You need 2/6 of an inverter
    IC, two small caps, and a 1Meg resistor. These are generally used for
    cost-sensitive microcontrollers, and are more than accurate enough to clock
    serial comm and most other things (+/- 0.5%).

    http://www.maco.panasonic.co.jp/www-data/pdf/APA0000/APA0000CE2.pdf


    Good luck.
    Chris
     
  8. Have you looked at CD4060 ? Similar bug with internal oscillator.

    http://www.ee.washington.edu/stores/DataSheets/cd4000/cd4060.pdf

    GG
     
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