[time-nuts] Recording mains frequency

Daniel Mendes dmendesf at gmail.com
Sun Mar 1 11:32:19 EST 2015

On 28/02/2015 16:58, Charles Steinmetz wrote:
> Daniel wrote:
>> I designed a board with an OCXO, pic microcontroller, power supply,
>> mains interface with optocoupler, and SD card for data
>> collection..    *   *   *  The boards also have a small Li-Ion
>> battery and battery charger for short power outages. Boards are
>> manufatured and the most expensive items have been bought, but not
>> everything yet.
> I'm not a grid-nut myself, but your project sounds very interesting.
> I designed the "simple zero-cross detector" because it appeared to me
> that many potential grid-nuts may be put off by the need to design and
> construct data collection tools, and I thought that a very simple
> hardware detector running into an RS232 port might lower this barrier
> enough to allow more prospective grid-nuts to play.  But there is
> still the matter of receiving, formatting, and storing the raw data,
> and the need to leave a computer on 24/7.  Your hardware solves these
> issues.

Yes... Even at my house it would be cumbersome to let something so big
turned on 24/7 (small child, wife....). Ask for others to do it just
wouldn´t work, so I designed something that fitted into a small box.

> Can you share the construction details (schematics, firmware, board
> files)?

It´s not assembled yet. Still need to buy about half the components (but
the most expensive ones are already in hand). I´m sending the schematics
attached (no more... to big for the list... sent directly). When it´s
assembled and running i´ll post all the info somewere freelly avaiable
(i´m trying to start a blog with all the crazy junk I make...).

> Do you plan to make boards or kits available?

No... but I have spare boards I can send away for free if someone wants
them. I just need to discover how to send them from Brazil overseas..
but it can´t be hard.

> Also, you say you plan to "synchronize a counter between them." How do
> you plan to do that without some sort of common-view timing source at
> each site (GPS, NTP, etc.), or do you plan to have common-view timing?

I plan to sincronize once (when they are powered on and near each
other). They will be calibrated as well as I can (I have two 12 digits
frequencimeters). After that they can drift away, but I expect that the
OCXOs will make that negligible....

> Very interesting project -- congratulations, and please keep us updated.



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