Re: [time-nuts] Building a mains frequency monitor

Guten nacht Attila, On 04/14/2016 12:24 PM, Attila Kinali wrote: God middag Magnus, On Thu, 14 Apr 2016 03:38:38 +0200 Magnus Danielson wrote: The professional equipment does it this way. It samples, filters and decimate the data. For the professional use the

Re: [time-nuts] Building a mains frequency monitor

God middag Magnus, On Thu, 14 Apr 2016 03:38:38 +0200 Magnus Danielson wrote: > The professional equipment does it this way. It samples, filters and > decimate the data. For the professional use the absolute phase is > relevant, so group delay needs to be flat,

Re: [time-nuts] Building a mains frequency monitor

Attila, On 04/11/2016 12:19 AM, Attila Kinali wrote: Why all these complicated filtering systems? As Jim wrote, we live in a digital world. One can easily sample the 60Hz with an ADC, 200sps is more than enough, the resolution doesn't need to be good either, 8bit would be sufficient. Do some

Re: [time-nuts] Building a mains frequency monitor

Hi The same “Collins Limiter” stuff that goes along with DMTD’s applies to 60 Hz power measurement as well. There is a “magic bandwidth” that combined with a slew rate will give you an optimum result. The gotcha is that you need to know the noise parameters inorder to work it out. Even back

Re: [time-nuts] Building a mains frequency monitor

Tektronix used transformer isolation followed by a low pass RC filter with about a 1 kHz cutoff; this was fed directly into the trigger source selector just like any other trigger source. There is still enough noise present that the trigger coupling can be used to select specific features to

Re: [time-nuts] Building a mains frequency monitor

Hi all, This is an interesting thread. I have built many clocks using the mains as a reference and have settled on a "belt and braces" approach that works well and does not seem to pass noise or transients. I begin with low voltage AC from the mains transformer and use it to feed the input

Re: [time-nuts] Building a mains frequency monitor

Nick wrote: At one point, I did try an LM393 instead of a 358. The result was that noise caused excessive false triggering. The 358, so far as I can tell, when acting as a comparator lacked sufficient bandwidth and/or speed to keep up with the noise. My results also seemed to be on a par

Re: [time-nuts] Building a mains frequency monitor

just look what is happening in one amplifier which happened to be a bit to slow for for the passing trough signal. The part of the spectrum -- which can't make it -- although will not show up at the output, will not disappear, but --if the amplitude is large enough -- overdrive parts of the

Re: [time-nuts] Building a mains frequency monitor

" <time-nuts@febo.com> > To: "Bill Hawkins" <bill.i...@pobox.com> > Cc: "Discussion of precise time and frequency measurement" > <time-nuts@febo.com> > Subject: Re: [time-nuts] Building a mains frequency monitor > > > > On Apr 9, 20

Re: [time-nuts] Building a mains frequency monitor

At one point, I did try an LM393 instead of a 358. The result was that noise caused excessive false triggering. The 358, so far as I can tell, when acting as a comparator lacked sufficient bandwidth and/or speed to keep up with the noise. The result was that the per-second cycle offsets

Re: [time-nuts] Building a mains frequency monitor

eviation and the like. In > that case, the occasional bad data or cycle slip is not a problem. Another > way to put it -- being a time nut is always harder than being a frequency > nut. > > /tvb > > - Original Message - > From: "Hal Murray" <hmur...@megap

Re: [time-nuts] Building a mains frequency monitor

ase, the occasional bad data or cycle slip is not a problem. Another > way to put it -- being a time nut is always harder than being a frequency > nut. > > /tvb > > - Original Message - > From: "Hal Murray" <hmur...@megapathdsl.net> > To: "Tom Van Baak" <t.

Re: [time-nuts] Building a mains frequency monitor

"Discussion of precise time and frequency measurement" <time-nuts@febo.com> Cc: <hmur...@megapathdsl.net> Sent: Monday, April 11, 2016 7:04 PM Subject: Re: [time-nuts] Building a mains frequency monitor >> record the duration of each cycle directly >> 5) Double wide

Re: [time-nuts] Building a mains frequency monitor

Nick wrote: The instructable I wrote about it is at [link] There's code for the Arduino and the Linux side as well as schematics. Several things to note about that front end circuit, from a time-nut perspective (the circuit was apparently created as a science project, and it may be fine

Re: [time-nuts] Building a mains frequency monitor

> record the duration of each cycle directly > 5) Double wide cycles are detectable but missed cycles are not. What do you mean by a double wide cycle? What do you mean by a missed cycle? They seem like the same thing - if you miss one, the next one will be twice as wide. > Here are the

Re: [time-nuts] Building a mains frequency monitor

> On Apr 11, 2016, at 2:31 PM, Tom Van Baak wrote: > > > 6) picPET output is directly readable by TimeLab via serial/USB. This one line item twigged my interest. Dedicating my 53220A to certain long running tasks that don’t require its full capabilities irks me a

Re: [time-nuts] Building a mains frequency monitor

AC > signal (via 1kR) on the PIC's Schmitt trigger input pin I got such clean data > for days and months at a time that I never went back and made it more > complicated. I now log once a second (instead of once a cycle). > > /tvb > > - Original Message - > Fro

Re: [time-nuts] Building a mains frequency monitor

ce a second (instead of once a cycle). /tvb - Original Message - From: "Jay Grizzard" <elfchief-timen...@lupine.org> To: <time-nuts@febo.com> Sent: Wednesday, April 06, 2016 6:21 PM Subject: [time-nuts] Building a mains frequency monitor > Since it seems to be a week

Re: [time-nuts] Building a mains frequency monitor

>> A more modern name for a synchronous motor is a permanent magnet stepper >> motor. Any PM stepper, and a couple of microfarad capacitor becomes a >> synchronous motor when connected to the power line. I've seen a data sheet for a motor that's actually spec'd for both uses. I don't know how

Re: [time-nuts] Building a mains frequency monitor

IMHO the transients and harmonic content, are more interesting than the 60Hz frequency! But if the 60Hz frequency with superb rejection of transients is the only goal: The 60Hz line clock chips of the 1970's used the LV transformer secondary, a single pole of RC low-pass filtering to get rid of

Re: [time-nuts] Building a mains frequency monitor

On Wed, 6 Apr 2016 18:21:43 -0700, you wrote: >... > >Q1: Assuming the schmitt trigger in the picPET triggers at a consistent >point in the waveform, the frequency at any given cycle is easy to >calculate: 1.0 / (timestamp2 - timestamp1)...but, is there a better >way? That method just

Re: [time-nuts] Building a mains frequency monitor

On 4/10/16 3:19 PM, Attila Kinali wrote: On Sun, 10 Apr 2016 12:03:51 -0700 jimlux wrote: On 4/9/16 10:20 PM, Bill Hawkins wrote: The schematic is too simple. There is noise on the power line from switching things on and off, leakage from dimmers and switching power

Re: [time-nuts] Building a mains frequency monitor

cfhar...@erols.com said: > A more modern name for a synchronous motor is a permanent magnet stepper > motor. Any PM stepper, and a couple of microfarad capacitor becomes a > synchronous motor when connected to the power line. The old pre-digital way of generating a rotating field for a

Re: [time-nuts] Building a mains frequency monitor

I just finished similar project recently. I am using OCXO 9,830400MHZ as the reference. My MCU driven by this crystal (No PLL). And I was using opto-coupler as ZCD. At the begining I was using every crossing (which 120 times per second in case of 60Hz). However that design was not good. Long

Re: [time-nuts] Building a mains frequency monitor

A more modern name for a synchronous motor is a permanent magnet stepper motor. Any PM stepper, and a couple of microfarad capacitor becomes a synchronous motor when connected to the power line. -Chuck Harris jimlux wrote: Alternatively, use a synchronous motor driving a load with

Re: [time-nuts] Building a mains frequency monitor

On Sun, 10 Apr 2016 12:03:51 -0700 jimlux wrote: > On 4/9/16 10:20 PM, Bill Hawkins wrote: > > The schematic is too simple. There is noise on the power line from > > switching things on and off, leakage from dimmers and switching power > > supplies, and the occasional

Re: [time-nuts] Building a mains frequency monitor

> On Apr 9, 2016, at 10:20 PM, Bill Hawkins wrote: > > The schematic is too simple. There is noise on the power line from > switching things on and off, leakage from dimmers and switching power > supplies, and the occasional animal that gets across the HV distribution >

Re: [time-nuts] Building a mains frequency monitor

On 4/9/16 10:20 PM, Bill Hawkins wrote: The schematic is too simple. There is noise on the power line from switching things on and off, leakage from dimmers and switching power supplies, and the occasional animal that gets across the HV distribution line, not to mention lightning, induced or

Re: [time-nuts] Building a mains frequency monitor

The schematic is too simple. There is noise on the power line from switching things on and off, leakage from dimmers and switching power supplies, and the occasional animal that gets across the HV distribution line, not to mention lightning, induced or direct. A simple capacitor will reduce high

Re: [time-nuts] Building a mains frequency monitor

On 4/8/2016 7:19 PM, Nick Sayer via time-nuts wrote: The instructable I wrote about it is at http://www.instructables.com/id/Science-fair-How-accurate-is-the-AC-line-frequency/ There’s code for the Arduino and the Linux side as well as schematics. Hi Nick, Awesome, thanks mucho!!! thanks

Re: [time-nuts] Building a mains frequency monitor

It works the same on PC hardware The PPS causes an interrupt and the handler captures the value of a counter that is driven by the system clock. It is typically a nanosecond level clock that just free runs. It saves the captured value were a user level process can read it. The user level

Re: [time-nuts] Building a mains frequency monitor

The instructable I wrote about it is at http://www.instructables.com/id/Science-fair-How-accurate-is-the-AC-line-frequency/ There’s code for the Arduino and the Linux side as well as schematics. > On Apr 8, 2016, at 10:32 AM, Ben Hall wrote: > > On 4/6/2016 11:34 PM, Nick

Re: [time-nuts] Building a mains frequency monitor

On 4/6/2016 11:34 PM, Nick Sayer via time-nuts wrote: fed into a Raspberry Pi serial port that was running a simple daemon that logged every line it got to syslog. Syslog is handy because it timestamps everything for you and keeps rotating log files and the like. Would you be so kind as to

Re: [time-nuts] Building a mains frequency monitor

A good source for what is actually going on with power line frequency is the web site of the University of Tennessee, which in partnership with Oak Ridge National Labs has a mains frequency monitoring program at http://fnetpublic.utk.edu/. The "Table Display" page shows frequency data for the

Re: [time-nuts] Building a mains frequency monitor

.@hotmail.com> To: <time-nuts@febo.com> Sent: Wednesday, April 06, 2016 10:27 PM Subject: [time-nuts] Building a mains frequency monitor > And that can be very interesting... a while back I read some stories on how > the NSA, police, etc could find out where an audio recording was m

Re: [time-nuts] Building a mains frequency monitor

2 PM > To: time-nuts@febo.com <javascript:;> > Subject: [time-nuts] Building a mains frequency monitor > > Since it seems to be a week for new projects on time-nuts... ;) > > So I've been wanting to set up a power line frequency monitor for a > while, and now(ish) seem

Re: [time-nuts] Building a mains frequency monitor

Transformers really are nearly noiseless. They can pick up magnetic fields but most of that is the 60Hz you are trying to measure. (the problem is normally with audio transformers picking up the 60Hz) A transformer is by far the safest way to go. I'd even go so far as to use a split bobbin type

Re: [time-nuts] Building a mains frequency monitor

bill.i...@pobox.com said: > You are looking for parts per thousand at most. Precision GPSDO 10 MHz is > overkill. That depends on the time scale you are interested in. If you want to plot the line frequency on the scale of seconds or minutes, then a junk crystal is probably good enough. If

[time-nuts] Building a mains frequency monitor

And that can be very interesting... a while back I read some stories on how the NSA, police, etc could find out where an audio recording was made by correlating AC hum in the recording with logs that they had of the power grids. Apparently logging AC mains is rather popular among the spooky /

Re: [time-nuts] Building a mains frequency monitor

Jay wrote: Q3: The open-ended question: How do I improve on this? I suspect the main place for improvement will be in the trigger, but I'm not sure where to go with that. Most designs I've seen involve a schmitt trigger, generally with reference voltages set by things like voltage dividers.

Re: [time-nuts] Building a mains frequency monitor

I've monitored line frequency with one of my old HP frequency counters. A filament transformer with a potentiometer across the secondary allows me to dial a safe voltage for the counter, about 1 V RMS. My ancient counters are limited in their data collection abilities; I'm sure your picPET device

Re: [time-nuts] Building a mains frequency monitor

, that is. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jay Grizzard Sent: Wednesday, April 06, 2016 8:22 PM To: time-nuts@febo.com Subject: [time-nuts] Building a mains frequency monitor Since it seems to be a week for new projects

Re: [time-nuts] Building a mains frequency monitor

I did this not too long ago. I used GPS PPS as the reference. I took a 9v wall wart, pinned one side to ground, ran the other through a rectifier diode and into one input of an LM358 wired as a comparator, comparing to 2.5 volts (Vcc/2). The 358 was slow enough that hysteresis wasn’t required.

Re: [time-nuts] Building a mains frequency monitor

lock-ani.gif /tvb - Original Message - From: "Jay Grizzard" <elfchief-timen...@lupine.org> To: <time-nuts@febo.com> Sent: Wednesday, April 06, 2016 6:21 PM Subject: [time-nuts] Building a mains frequency monitor > Since it seems to be a week for new projects on time

[time-nuts] Building a mains frequency monitor

Since it seems to be a week for new projects on time-nuts... ;) So I've been wanting to set up a power line frequency monitor for a while, and now(ish) seemed to be a good time for me. So initially, I was planning on doing a simple design that was posted here a couple of years back, which