Hi guys. is it possible to get 1PPS signal from 50Hz A/C power line ? I want to make a clock with high accuracy and I need an accurate time signal.
thanks.
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A GPS module would be a much better choice.
The "50 Hz" is nominal, and is frequently adjusted by the power company so that digital clocks keep time, on average.
Well, for a place that has no view of the sky, I have to use a source other than GPS.
Please define "high accuracy" so that we have some basis for discussion.
To synchronize two Arduino boards that are 500 meters apart with microseconds accuracy
Buy a TCXO (temperature controlled crystal oscillator) module with sufficient stability.
For example: https://www.digikey.com/en/product-highlight/r/raltron/rtx-series-tcxos
You mean, synchronous arduino boards with environment temperature ?
No.
Hi! Yes it is possible, there are a lot of cheap clock that use this metod: 50 (or 60) Hz AC power line is very accurate and stable (think about all old tv sync made by ac 50 Hz signal).
You can use a divider by 50 to obtain 1 Hz, then drive a analog or digital clock.
You can also use the TMS3450NL to drive a display directly from 50/60 Hz signal.
Why no??? Yes forever!
Accuracy and stability of the 50 Hz mains frequency
With one pulse per second, how would you EVER synchronize two Arduino boards? IF different, which one would change? OR would both try to change? How would one board know when the other had a one second pulse?
Assuming you have a transformer for safe & low-voltage AC you can use a comparator to make a square wave, then you can make a frequency divider.
It's common for AC clocks to be run from the power line frequency. I have a digital clock with a batter back-up but when the power goes out the accuracy is terrible... The time is several minutes off by the time the power comes back-on.
Analog AC clocks use synchronous motors so they can also be "perfect" as long as you don't lose power.
Thank you for your attention and response. So is a schematic of this circuit available? And can the output of 1 PPS be taken from it?
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And which cycle of the 50 Hz will the 1 second pulse be keyed on?
A zero-cross detector will result a pip, as it were, with each alternation (50Hz line freq. → 100Hz ZCD)
That works for each of the clocks, but does not control WHICH of the zero crossings the clocks will be tied to. The OP wants them to use the SAME zero crossing point to generate identically timed pulses.
230 VAC 50 Hz changes by only 0.1 V per us. I doubt it is possible to get microsecond synchronization from mains. Why do you want this? What is distance between the Arduinos?
I derived a similar scheme for mS timing using the 1 pps output from a low cost GPS module. I want to triliterate impact sound on a lake. Of course the lake gives a clear sky view of the sky.
I think I could get better than 1uS.
I lack coding skills and have had insufficient time to persue this. I have a block diagram somewhere on another PC's HDD.