Help with backup circuit for digital clock

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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: https://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.
 
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?
 
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Wow, that simple?!
And that mod even reduces the number of components, perfect!
 
the_engineeer said:
Wow, that simple?!
And that mod even reduces the number of components, perfect!
Click to expand...
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
 
spec said:
(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)
Click to expand...

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.
 
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

 
the_engineeer said:
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

View attachment 98787
Click to expand...

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

spec
 


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.
 
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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!
 
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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