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Help with backup circuit for digital clock

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by the_engineeer, Apr 1, 2016.

  1. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    spec needs a pat on the back once in a while. He's new here.

    BTW: I'm following the thread but I would like a 60 Hz backup unit which would switch from power line to external oscillator. You get better long time accuracy using the power grid. Trouble is not even on the list of projects that needs doing. I did have a MM5369 (color burst to 60 Hz) and a 9V battery, but it never worked some 35 years ago. I know more now.

    Here's the clock: http://www.electro-tech-online.com/threads/screwwwwss.147698/#post-1258711 Not much room to work either, The full "Blueprint" SHOULD be under a rug somewhere.
     
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  2. the_engineeer

    the_engineeer Member

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    That's another good idea, this little retro clock idea of mine really ballooned into something truly awesome!

    Please keep in mind though that I live in Sweden - we have 50Hz power lines... To make this an "universal" clock module there should be a jumper or a dip switch where you can choose 50 or 60 Hz mains.

    And this circuit should perhaps be an optional module for the presumptive builder, one of my original project ideas was to NOT have a built in power supply but simply be able to power it from any 5V/1A source - but don't get me wrong, it is a perfect addon!

    ...and while we're at it, why don't a make a GPS time input module for the really accurate min's and sec's? :D
     
    Last edited: Apr 6, 2016
  3. the_engineeer

    the_engineeer Member

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    Wow, that simple?!
    And that mod even reduces the number of components, perfect!
     
  4. dave

    Dave New Member

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  5. spec

    spec Well-Known Member Most Helpful Member

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    Glad you are pleased: I was surprised that a clock module was so cheap and consumed so little power.

    (just leave a message asking the moderators to delete any erroneous posts- they are pretty efficient on ETO and it wont be long before they are gone)

    spec
     
  6. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    e.g. Use the "Report" button and ask the mods to delete the post presumably after you have edited edited to something like <self deleted> or <double post> etc.
     
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  7. the_engineeer

    the_engineeer Member

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    I've made the PCB layouts now, still have to go through them a couple times more and perhaps make a prototype of the "UPS" module but I managed to reach one of my project goals - to fit everything between the display legs :)

    presentation.jpg
     
  8. spec

    spec Well-Known Member Most Helpful Member

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    Pretty neat eng, especially as you are just starting with the ECAD package. :cool:

    spec
     
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  9. the_engineeer

    the_engineeer Member

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  10. spec

    spec Well-Known Member Most Helpful Member

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    Last edited: Apr 8, 2016
  11. the_engineeer

    the_engineeer Member

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    Long time no see...
    I've been busy doing actual salary-paying work, but now I have a little free time again to continue with this project.
    Regarding R3 and R6, it seems that 0603 resistors with 1.42 / 2.23 MOhms are very hard to find. Do you think that 1.43 and 2.21 will suffice?
    I'd rather not go up in package size for these, if it's not absolutely necessary.
     
    Last edited: Dec 21, 2016
  12. audioguru

    audioguru Well-Known Member Most Helpful Member

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    The Varta Li-Ion coin cell withstands their overcharge test with 12V at 300mA for 12 hours and it doesn't explode nor catch on fire!
     
  13. spec

    spec Well-Known Member Most Helpful Member

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    Hi engineer,

    Nice to see you back.

    Being paid for work is always handy.:)

    The resistor values that you want to use will be fine.

    spec
     

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