BUT, before you get carried away, here is a worthwhile article to read about a
descrete circuit. The important thing is to read his description about how the
circuit works and why he chose this particular circuit layout. It is quite
interesting !
http://www.dextrel.net/diyzerocrosser.htm
On Sun, Jul 3, 2011 at 8:57 AM, Tom Van Baak t...@leapsecond.com wrote:
At first this sounds a bit bold. I mean, there's lots of noise on the power
line. Sometimes horrible spikes and all that. Surely, at some point a
cheap counting circuit is going to be confused.
What makes is easy are two
OK, I wasn't paying attention as the info passed by. 'Xactly how is this
huge signal introduced to the PC? I remember something about a voltage
divider off the hot side of the line, put on an input pin of the PC's
com port and then somehow timestamped and put on a data file. Howsat
done again?
OK, I wasn't paying attention as the info passed by. 'Xactly how is this
huge signal introduced to the PC? I remember something about a voltage
divider off the hot side of the line, put on an input pin of the PC's
com port and then somehow timestamped and put on a data file. Howsat
done again?
Hi Jim,
Thank you so much for your kind reply! I had looked through diligently
TrueTime's site prior to my original post, and just finished looking
through Symmetricom's site, and found a very handy index, but I can't
locate schematics or board-level pictorials of the main board. Also,
On 07/03/2011 09:37 PM, Tom Van Baak wrote:
Note looking for a sample 990 to 1010 milliseconds from the last
sample is a nice way get 1PPS from 60 Hz. This is more immune
to noise than traditional division-by-60 techniques.
As it turns out, I've gotten clean 1PPS data with no h/w or s/w
Hi Tom,
The part that I am confused on is how the DCD pin is being accessed and time
stamped. Where would I find software for that purpose ?
Perhaps some of the others can straighten me out ? Especially if there is
software that will run on an old Win 98 laptop.
BillWB6BNQ
Tom Van Baak
Hi Don,
After Tom referred to the app note, I went and looked it up. While it is
functional I would, by no means, ever suggest anyone actually use that method.
It presents the possibility for personal injury and circuit failures. Even for
a
skilled veteran, all it takes is one thoughtless
Hi!
On 07/04/2011 12:32 AM, WB6BNQ wrote:
Hi Don,
After Tom referred to the app note, I went and looked it up. While it is
functional I would, by no means, ever suggest anyone actually use that method.
It presents the possibility for personal injury and circuit failures. Even for
a
skilled
Why not kill two birds with one stone. Make a quiet
linear power supply and use the low voltage AC for
the zero crossing reference.
--
Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
Omen Technology Inc The High
Hi Bill: I agree! even using a transformer without optoisolation gives
me pause ... I just found the stuff, don't suggest it.
Don
WB6BNQ
Hi Don,
After Tom referred to the app note, I went and looked it up. While it
is
functional I would, by no means, ever suggest anyone actually use that
Hi Tom,
The part that I am confused on is how the DCD pin is being accessed and time
stamped. Where would I find software for that purpose ?
Perhaps some of the others can straighten me out ? Especially if there is
software that will run on an old Win 98 laptop.
BillWB6BNQ
Hi Bill,
Here's yet another way to monitor power line timekeeping...
This is about half a day from a webcam, taken at 15 minute
intervals by a PC, compressed to a 12 second animated GIF.
http://www.leapsecond.com/pages/tec/mains-clock-ani.gif
/tvb
___
At 09:54 PM 7/3/2011, Tom Van Baak wrote:
This is about half a day from a webcam, taken at 15 minute
intervals by a PC, compressed to a 12 second animated GIF.
http://www.leapsecond.com/pages/tec/mains-clock-ani.gif
That's funny...I picked up a mains clock yesterday and started
something
I've moved the 60 Hz stuff from
http://www.megapathdsl.net/~hmurray/time-nuts/
to
http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/
--
The main graph is now up to sightly over 4 days.
http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz.png
Peak-to-peak is almost 8 seconds.
Hal,
That's good stuff. Sadly, I've got to convert UTC to your local time to
interpret the results, so I haven't done it. Tom's MJD will be even worse.
The reason is that the loads that cause frequency droop occur during
workdays. Lost cycles are made up at night, so I need to know when local
Hal,
That's good stuff. Sadly, I've got to convert UTC to your local time to
interpret the results, so I haven't done it. Tom's MJD will be even worse.
Bill,
If you know C, see mjd_code.c under www.leapsecond.com/tools/.
Otherwise, if you use Excel it's even easier -- just subtract the
magic
Group,
The effort to track power line frequency changes is laudable. I think
the effort to determine the stiffness of the network by measuring the
phase angle between GPS time and local line zero crossings is most
interesting. But the following is about the frequency control problem.
The main
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