Yann Guidon / YGDESMy lousy 32768Hz oscillator is expected to drift... and I have no idea by how much.
I'm stocking DS32KHZ chips but that will only help a bit. My idea is to reset everything at midnight, so I'm thinking about a DCF77 receiver, such as featured here.
However, stock in Paris is low, prices are now low and reliability is not stellar, which means : complex logic, a microcontroller, code...
Can anybody help me to find/source decent and affordable DCF77 demodulators ? Conrad has some but I wish other stores stocked it.
Update: there is now a project dedicated to this question: #1ppd: Midnight Reset
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The idea may be a bit more expensive but you might also want to consider something like a GPS module with a PPS output, or maybe a microcontroller add-on to decode the time from the NMEA data and generate an accurate PPS?
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Hi Kumar !
The "midnight reset" idea is just an additional feature that makes the project more functional.
GPS receivers are easier to source and not restricted to western Europe. Prices are slowly getting lower. However, indoor reception is not... good. Antenna design is critical, but still dependent on the environmen which is not controlled.
The PPS output is great however it misses the "educational value", the signal will come from a "magic black box". And honestly, making a 32KHz Xtal oscillate correctly is a design challenge... that was waiting to be tackled.
As a compromise, I will test with a DS3231 TCXO: it works everywhere (no radio reception), it's quite precise (around 1ppm ?), cheap, tiny and easily sourced. But ideally there would not be an integrated circuit...
Any further thought ?
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