On October 17, 2015 6:09:21 PM CDT, Tim Lavoie <tim@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 happens.

 On Oct 17, 2015, at 14:36, Trevor Cordes <trevor@tecnopolis.ca> wrote:
 
 Off-topic, but cool:
 
 http://www.transistorclock.com/?imm_mid=0da80b&cmp=em-prog-na-na-newsltr_20151017
 
 A guy selling kits to make a all-parts-exposed digital wall clock that 
 uses *no ICs* and *no crystals*.  You build it yourself, 1250 parts to 
 solder onto a custom board.  Too pricey for me, otherwise I'd love to put 
 one together.
 
 ICYW, I dug around the FAQ and he is cheating a bit: he's using the 60Hz 
 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?

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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
--
Daryl F