On 2/12/21 8:23 AM, Thomas D. Erb wrote:
"I would think they try to hold it over 1 day, so that mains driven
clocks don't run slow or fast.? That being said, I wonder how many
clocks are still being built using a synchronous motor drive? Given that
all the clocks on appliances in my kitchen have drifted apart, I'll bet
they use their internal microcontroller crystal as a reference."
Actually I think all of my kitchen appliances use line frequency for time
reference - it's so easy to count.
Maybe.. you've got to condition the AC from the secondary side of the
transformer and use a pin to bring it in on, which requires at least 2
or 3 passive components, and you already have a crystal for the
microcontroller (thinking here of oven timers and the like, which have a
numeric display). These applications are super price sensitive, and
those 2 or 3 components cost money, in components, in board space, and
in assembly costs. Pennies to be sure, but...
And the fact that my appliances drift on the order of a minute in a
month, differently. So maybe some count cycles and some have a rock.
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