[time-nuts] Simple AC mains zero-cross detector

Charles Steinmetz csteinmetz at yandex.com
Wed Dec 17 04:03:44 EST 2014

Hal wrote:

>What are you going to do with data from the line accurate to 1 microsecond?

Me?  Nothing.  I don't find the meanderings of the mains frequency 
all that interesting, aside from observing them from time to time via 
the sweep second hand of a synchronous wall clock.  But lots of other 
folks do (including our fearless leader, tvb), and they like being 
able to correlate grid events to single-digit uS (lightning strikes, 
sections of the grid going out, etc.).  That said, I didn't slave 
away trying to get the ZCD jitter below 1uS -- I anticipated that it 
would be, just because there's nothing in the design to prevent it, 
so I wasn't surprised when it worked out that way.

Best regards,


Everything works if you let it.
      Corpus C. Redfish

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