[RndTbl] transistor wall-clock
wyatt at prairieturtle.ca
Sat Oct 17 23:02:07 CDT 2015
On October 17, 2015 6:09:21 PM CDT, Tim Lavoie <tim at fractaldragon.net> wrote:
>The AC frequency as a clock source will also be a problem of the
>utility happens to mess with that timing. Forget why the do, but it
>> On Oct 17, 2015, at 14:36, Trevor Cordes <trevor at tecnopolis.ca>
>> Off-topic, but cool:
>> A guy selling kits to make a all-parts-exposed digital wall clock
>> uses *no ICs* and *no crystals*. You build it yourself, 1250 parts
>> solder onto a custom board. Too pricey for me, otherwise I'd love to
>> one together.
>> ICYW, I dug around the FAQ and he is cheating a bit: he's using the
>> of the AC as a timer source.
>> Hmm, since it plus into AC, does that mean touching some parts of the
>> exposed circuits might give you a nice zap?
>> Roundtable mailing list
>> Roundtable at muug.mb.ca
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When the A/C grid is heavily loaded the generators slow below 60Hz.
The make up for it in later by generating higher than 60Hz. That's why the old A/C clocks with synchronous motors never need correction over long periods of time.
Most cheap digital clocks haven't had the oscillator regulated so their time creeps off.
NTP fan, Daryl
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