Electronics > Beginners

Kit review - Generic AliExpress Digital Clock.

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magic:
It can be an exercise on its own to measure ppm/°C, ppm/V, ppm/pF and "pull" them to the right frequency :-DD

bd139:

--- Quote from: Bud on September 13, 2019, 01:03:56 pm ---'Cause those DS1302 were made in a Shenzhen shop on a back alley on a rainy day?

--- End quote ---

I think they were the ones that ended up in a large sack thrown out the back because they were out of tolerance.


--- Quote from: magic on September 13, 2019, 01:43:02 pm ---It can be an exercise on its own to measure ppm/°C, ppm/V, ppm/pF and "pull" them to the right frequency :-DD

--- End quote ---

 :-DD

JackJones:

--- Quote from: tooki on September 13, 2019, 11:39:35 am ---I don't know what causes the DS1302/1307 based clocks to be so unpredictable in their accuracy, but at some point, it just ceases to be fun...

--- End quote ---

They use an external crystal which is probably the cause. I've used a DS1307 with a crystal from a random seller before and it was at least +- 1 minute per day. With a crystal from a reputable seller the results were much better.

And I agree, DS3231 is the way to go. Unless you get a dud. Better buy them from a reputable seller too!

wraper:

--- Quote from: Bud on September 13, 2019, 01:03:56 pm ---'Cause those DS1302 were made in a Shenzhen shop on a back alley on a rainy day?

--- End quote ---
DS3231 has built in TCXO but DS1302 uses external crystal which most likely is of questionable quality. Not to say that likely they just use some random crystal instead of with required 6pF loading capacitance.

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