Re: [time-nuts] Local Solar Time Clock
On Sat, Jan 18, 2014 at 11:14 PM, David J Taylor david-tay...@blueyonder.co.uk wrote: Are you perhaps thinking of sidereal time, Chris? Either way, the difference is within the limits of the basic tin wind-up alarm clock. A quality wrist watch would not work because it is to good and harder to adjust. Something like this: Westclox-15396-Ardmore-Twin-Bellhttp://www.amazon.com/Westclox-15396-Ardmore-Twin-Bell/dp/BV0DEW/ref=pd_sim_hg_1 Now if the OP wants to track apparent solar time to better then a few seconds per month, then it gets real hard if you have to do it with springs, pendulums and gears because the clock needs to track the date. I think you might need some kind of of non-round cam that revolves once per year. But if you are willing to set the clock about once a week a cheap wind-up clock would be good enough to tell visually you when the sun is at local noon to within a minute or so. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
I wonder if you really need a special clock? Can't you adjust a normal spring driven clock to run fast (or is it slow?) by about 1/3 of a percent (one day per year)? This should be within the range of adjustment. Chris, When you mention 1/3 percent, you're thinking sidereal time, which is a completely different concept, and much easier to implement than equation of time. Sidereal time is simply a calendar-day independent, fixed (2730 ppm) frequency offset. I already have PIC chips that do this; see PD28 under www.leapsecond.com/pic/picdiv.htm or read the comments in the source code at: http://www.leapsecond.com/pic/src/pd28.asm Solar time, on the other hand, is continuously variable in rate (and phase) throughout the whole year. A microprocessor implementation of solar time also needs to know calendar date, time, and longitude. A 4800 baud GPS NMEA stream input would be a convenient way to obtain this information. Without using floating point or trig functions, a tiny PIC implementation would probably use a 365 entry lookup table to adjust the output tick rate on a per-day basis. A more capable Arduino or RPi might allow one to accurate calculate EOT directly from planetary motion equations, avoiding hard-coded tables altogether. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Local Solar Time Clock
To Jim Lux. After you get it working, would you consider putting the details online, or selling as a kit? P Nielsen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Gosh, Spring Wound would be hard pressed for even sidereal time. I know I can't do that with my Atmos which is a definite step up from spring. Lee - Original Message - From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, January 19, 2014 6:25 AM Subject: Re: [time-nuts] Local Solar Time Clock I wonder if you really need a special clock? Can't you adjust a normal spring driven clock to run fast (or is it slow?) by about 1/3 of a percent (one day per year)? This should be within the range of adjustment. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On Sat, Jan 18, 2014 at 10:09 PM, David J Taylor david-tay...@blueyonder.co.uk wrote: I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. Is there a commercial product or kit available for this? For a mechanical clock, probably not. The problem is demonstrated by what I suggested that you do with a stick and pebbles. By marking the position of the sun to locate the point where the sun is highest in the sky you identify local solar noon. By marking the position of the sundial's shadow at a fixed time every day relative to GMT you will find that, over the course of a year, your shadow will inscribe an analemma, whose lateral displacement represents the correction factor between sidereal (GMT) noon and local solar noon. This is all caused by the tilt of the rotational axis of the earth which causes the poles to be displaced either advanced or retarded relative to the centroid at the equinoxes. (Equinoxae?) So your mechanical clock would need to speed up and slow down in a smooth fashion twice over the course of a year. Pretty hard to do with a mechanical clock. Definitely a job for a uP. BUT a really cool thing would be to interface a camera to find the point in time where YOUR local noon actually occurs and corrects the clock. Automatic meridian circle anyone? -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Hi Even a small PIC has room for a fairly large table. Rather than dealing with leap years outside the table, just make it 4 years long rather than one year. If you are trying to deal with 15 minutes, the table could get to 0.1 second with two bytes per entry. It would fit in 3K bytes. It would be half that size if you used some sort of “sum the bytes” compression approach. You would do 1,500 adds to get the number for today. I’d bet that can be done in 24 hours. You still need to deal with the century stuff and ummm …. e …. (dare I bring it up …) leap seconds …. Bob On Jan 19, 2014, at 7:25 AM, Tom Van Baak t...@leapsecond.com wrote: I wonder if you really need a special clock? Can't you adjust a normal spring driven clock to run fast (or is it slow?) by about 1/3 of a percent (one day per year)? This should be within the range of adjustment. Chris, When you mention 1/3 percent, you're thinking sidereal time, which is a completely different concept, and much easier to implement than equation of time. Sidereal time is simply a calendar-day independent, fixed (2730 ppm) frequency offset. I already have PIC chips that do this; see PD28 under www.leapsecond.com/pic/picdiv.htm or read the comments in the source code at: http://www.leapsecond.com/pic/src/pd28.asm Solar time, on the other hand, is continuously variable in rate (and phase) throughout the whole year. A microprocessor implementation of solar time also needs to know calendar date, time, and longitude. A 4800 baud GPS NMEA stream input would be a convenient way to obtain this information. Without using floating point or trig functions, a tiny PIC implementation would probably use a 365 entry lookup table to adjust the output tick rate on a per-day basis. A more capable Arduino or RPi might allow one to accurate calculate EOT directly from planetary motion equations, avoiding hard-coded tables altogether. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
/tvb wrote: Solar time, on the other hand, is continuously variable in rate (and phase) throughout the whole year. A microprocessor implementation of solar time also needs to know calendar date, time, and longitude. A 4800 baud GPS NMEA stream input would be a convenient way to obtain this information. Without using floating point or trig functions, a tiny PIC implementation would probably use a 365 entry lookup table to adjust the output tick rate on a per-day basis. A more capable Arduino or RPi might allow one to accurate calculate EOT directly from planetary motion equations, avoiding hard-coded tables altogether. The question I haven't seen answered is what error band is acceptable to the OP. Mark has posted that it is not terribly difficult to get within small fractional minutes if you start with GPS time and position data, as he has done for a future release of LH. But getting to the millisecond level or better is likely much more difficult. The OP did say in a follow-up: I was hoping someone here might have come up with a cheap quartz clock driven by a microprocessor, and the necessary code. That would seem to be the most practical solution. One normally expects a quartz clock to stay within a few seconds or maybe a minute of true time, so unless stated otherwise the expectation may be similar for a clock reprogrammed to display solar time. As Tom points out, the clock would need to know its longitude as well as the conventional date and time -- so it would need GPS or some other nav aid to be fully automatic (otherwise it would need to be programmed manually for its actual longitude). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Hi You could do the time / date thing with a WWVB (or similar) receiver. There are a lot of cheap clocks (and kits) that work that way. The only thing you would need past that is location. Any mechanical implementation would have the same constraint. Bob On Jan 19, 2014, at 9:32 AM, Charles Steinmetz csteinm...@yandex.com wrote: /tvb wrote: Solar time, on the other hand, is continuously variable in rate (and phase) throughout the whole year. A microprocessor implementation of solar time also needs to know calendar date, time, and longitude. A 4800 baud GPS NMEA stream input would be a convenient way to obtain this information. Without using floating point or trig functions, a tiny PIC implementation would probably use a 365 entry lookup table to adjust the output tick rate on a per-day basis. A more capable Arduino or RPi might allow one to accurate calculate EOT directly from planetary motion equations, avoiding hard-coded tables altogether. The question I haven't seen answered is what error band is acceptable to the OP. Mark has posted that it is not terribly difficult to get within small fractional minutes if you start with GPS time and position data, as he has done for a future release of LH. But getting to the millisecond level or better is likely much more difficult. The OP did say in a follow-up: I was hoping someone here might have come up with a cheap quartz clock driven by a microprocessor, and the necessary code. That would seem to be the most practical solution. One normally expects a quartz clock to stay within a few seconds or maybe a minute of true time, so unless stated otherwise the expectation may be similar for a clock reprogrammed to display solar time. As Tom points out, the clock would need to know its longitude as well as the conventional date and time -- so it would need GPS or some other nav aid to be fully automatic (otherwise it would need to be programmed manually for its actual longitude). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Hi Bob, On 01/19/2014 04:26 PM, Bob Camp wrote: Hi You could do the time / date thing with a WWVB (or similar) receiver. There are a lot of cheap clocks (and kits) that work that way. The only thing you would need past that is location. Any mechanical implementation would have the same constraint. Bobinstructions My feverish brain now cranks out that all we need is a electromechanical WWVB receiver, thus no active electronic parts. That would be a nice little challenge. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
In message 52dbff99.3060...@rubidium.dyndns.org, Magnus Danielson writes: My feverish brain now cranks out that all we need is a electromechanical WWVB receiver, thus no active electronic parts. That would be a nice little challenge. The main challenge is an antenna which delivers sufficient power. I don't know the WWVB signal well enough, but decoding DCF77 by mechanical means wouldn't be too hard. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/19/14 2:00 AM, P Nielsen wrote: To Jim Lux. After you get it working, would you consider putting the details online, or selling as a kit? Half coded. I'll publish all the details.. It's pretty easy.. a Arduino, a clock, a wall wart to power it. I haven't tried it yet (no clock to test with until the stores open), but I'm assuming that it's just a wire from the digital output port to the clock. Might need a resistor in series. The other burning question is how accurate does it have to be. The scheme I have now basically has a table of rate vs day of year (which I still need to calculate). Right now, the EOT is changing almost 30 seconds/day, which implies that the clock could be some seconds off during part of the day (although true at noon). Given the tens of ppm accuracy of the crystal = some seconds/day it seems that I want a bit better algorithm. Rather than drive from a table, maybe actually calculating it. the Arduino is no ball of fire for floating point computation, but still, it doesn't have that much to do. It could be that I can just calculate the rate every second. But then I have to differentiate the equation of time... and I haven't had enough coffee yet to differentiate the chain of sinusoids analytically. P Nielsen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/19/14 1:49 AM, Chris Albertson wrote: On Sat, Jan 18, 2014 at 11:14 PM, David J Taylor david-tay...@blueyonder.co.uk wrote: Are you perhaps thinking of sidereal time, Chris? Either way, the difference is within the limits of the basic tin wind-up alarm clock. A quality wrist watch would not work because it is to good and harder to adjust. Something like this: Westclox-15396-Ardmore-Twin-Bellhttp://www.amazon.com/Westclox-15396-Ardmore-Twin-Bell/dp/BV0DEW/ref=pd_sim_hg_1 Now if the OP wants to track apparent solar time to better then a few seconds per month, then it gets real hard if you have to do it with springs, pendulums and gears because the clock needs to track the date. I think you might need some kind of of non-round cam that revolves once per year. That's what the 'equation clocks' in the Wikipedia article do. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
The usual quartz clock that runs off of a AA cell is a little trickier to drive than you might think. You need to feed its stepper motor coil with an alternating +1.5V and -1.5V pulse. The pulse follows the rising or trailing edge of a 1/2 Hz square wave. I have driven them using a series capacitor and resistor to ground...arranged as a differentiator, but I don't recall the part values anymore. You arduino could certainly be made to generate such a pulse using a couple of resistors and a couple of digital outputs in a simple DAC sort of circuit. -Chuck Harris Jim Lux wrote: On 1/19/14 2:00 AM, P Nielsen wrote: To Jim Lux. After you get it working, would you consider putting the details online, or selling as a kit? Half coded. I'll publish all the details.. It's pretty easy.. a Arduino, a clock, a wall wart to power it. I haven't tried it yet (no clock to test with until the stores open), but I'm assuming that it's just a wire from the digital output port to the clock. Might need a resistor in series. The other burning question is how accurate does it have to be. The scheme I have now basically has a table of rate vs day of year (which I still need to calculate). Right now, the EOT is changing almost 30 seconds/day, which implies that the clock could be some seconds off during part of the day (although true at noon). Given the tens of ppm accuracy of the crystal = some seconds/day it seems that I want a bit better algorithm. Rather than drive from a table, maybe actually calculating it. the Arduino is no ball of fire for floating point computation, but still, it doesn't have that much to do. It could be that I can just calculate the rate every second. But then I have to differentiate the equation of time... and I haven't had enough coffee yet to differentiate the chain of sinusoids analytically. P Nielsen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/19/14 9:17 AM, Chuck Harris wrote: The usual quartz clock that runs off of a AA cell is a little trickier to drive than you might think. You need to feed its stepper motor coil with an alternating +1.5V and -1.5V pulse. The pulse follows the rising or trailing edge of a 1/2 Hz square wave. I have driven them using a series capacitor and resistor to ground...arranged as a differentiator, but I don't recall the part values anymore. You arduino could certainly be made to generate such a pulse using a couple of resistors and a couple of digital outputs in a simple DAC sort of circuit. Yeah.. that *is* the challenge. Use two outputs and make a sort of H bridge ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Chris, Mechanical clocks that display local solar time have been built for over a hundred fifty years. There are mechanical wristwatches that also do the same thing and are currently available. They're extremely expensive but are being constructed. The local solar time is usually presented on the dial as a hand which displays the difference in time in minutes (+ or -) from that shown on the dial. It's a simple matter to subtract or add the difference to the local time shown on the dial to get solar time. I designed a clock to do this some 25 years ago and although a bit painful to make, not really all that difficult. The clock that I designed at the time used a differential to actually display the solar time on the dial directly. The solar time is determined in a clock or watch by means of a kidney shaped cam that is actually represents the anelemma and a follower on the cam moves a hand showing the difference in time from that shown on the local time dial. The difference in time is known as the equation of time. One such modern watch showing the equation of time can be seen here http://www.luxist.com/2010/03/09/girard-perregaux-1966-annual-calendar-and-equation-of-time-watch/ My personal interest has been constructing clocks showing sidereal time which is a bit complicated gearwise(if you want really good accuracy)n and one of mine can be seen here www.precisionclocks.com. I do remember seeing quite a few years ago an electric mains clock that had on the dial display an equation of time hand showing the difference between local time and solar time. I guess the bottom line is that although not impossible, it is a bit difficult. Bill_S On 1/19/2014 7:25 AM, Tom Van Baak wrote: I wonder if you really need a special clock? Can't you adjust a normal spring driven clock to run fast (or is it slow?) by about 1/3 of a percent (one day per year)? This should be within the range of adjustment. Chris, When you mention 1/3 percent, you're thinking sidereal time, which is a completely different concept, and much easier to implement than equation of time. Sidereal time is simply a calendar-day independent, fixed (2730 ppm) frequency offset. I already have PIC chips that do this; see PD28 under www.leapsecond.com/pic/picdiv.htm or read the comments in the source code at: http://www.leapsecond.com/pic/src/pd28.asm Solar time, on the other hand, is continuously variable in rate (and phase) throughout the whole year. A microprocessor implementation of solar time also needs to know calendar date, time, and longitude. A 4800 baud GPS NMEA stream input would be a convenient way to obtain this information. Without using floating point or trig functions, a tiny PIC implementation would probably use a 365 entry lookup table to adjust the output tick rate on a per-day basis. A more capable Arduino or RPi might allow one to accurate calculate EOT directly from planetary motion equations, avoiding hard-coded tables altogether. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
From: Jim Lux Right now, the EOT is changing almost 30 seconds/day, which implies that the clock could be some seconds off during part of the day (although true at noon). [] 30 seconds/day? http://www.sundials.co.uk/pix/c/eot3.gif from: http://www.sundials.co.uk/equation.htm Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Clockmakers have made equation of time clocks for centuries, but because of their complexity, they are quite rare. Most of them use a kidney shaped cam to move a lever to display the time difference from clock time and local solar time. (note - The Longnow clock uses a three dimensional EOT cam to cover the change over the 10,000 year life of the clock) The main use was to set your house clock to the correct time based on the time your garden sundial displayed. A slightly more clever way to display the difference was to move the minute scale on the clock about its center. An extremely small number of clocks 'calculated' the difference without the use of a cam. One example is the David Rittenhouse clock at Drexel University. I wrote up a description of the clock for the Horological Science Newsletter some time ago. I also created a simulation of the mechanism using Working Model 2D. A link to the simulation running on a youtube video is below with the text from the HSN article - since it is very difficult to read the text on the simulation on youtube. Rittenhouse's method suggests a mechanical addition to a inexpensive clock that is kept running continuously and just adjusted to the correct time occasionally. Also the formula or a more accurate one for a specific location could be done in code. Bob Holmström Editor Horological Science Newsletter www.hsn161.com http://www.youtube.com/watch?v=7_iovbjamIQ Rittenhouse Equation of Time Mechanism by Bob Holmström The equation of time dial on a clock indicates the difference between 12 noon on a clock dial (mean solar time), and noon as indicated by a sundial (apparent solar time). Early clocks could be set to time using a sundial and a printed table of mean solar time vs. apparent solar time for the location of the clock. Most clocks that go a step further and display equation of time on a dial use an “equation cam” to display the information. The David Rittenhouse Astronomical Musical Clock at Drexel University has an unusual equation of time dial mechanism that uses gearing and linkages to approximate the “equation of time”. Ronald Hoppes book on the Rittenhouse clock reviewed in this issue has a detailed description of the mechanism. Hoppes explains that the earth’s orbit is not circular, not centered on the sun, and the earth’s axis is tilted with respect to its orbit. He goes on to explain that a computer analysis of the three error terms results in a formula for the equation of time: E = 7.665 Sin(A) – 9.665 Sin(2B) – 0.31 Cos(2C) Where: A = [(360/365.25)N] B = [(360/365.25)(N-81)] C = [(360/365.25)(N-173)] N = the day of the year Hoppes explains how Rittenhouse’s combination of gears and linkages displays the equation of time based on the formula above. In order to understand the mechanism, I created a model using Working Model 2D to simulate the mechanism. A movie of the mechanism in motion is available online at: http://www.youtube.com/watch?v=7_iovbjamIQ or search for Rittenhouse and Equation of time at youtube.com – the text below only makes sense if you view the video. View the model full screen if possible and watch the dot on the graph move as the model runs. The horizontal motion of the dot on the end of the orange arm is the vertical axis on the graph. The text below the graph is difficult to read in the video – the important text is as follows: The grey gear rotates once per year and carries the green gear. The rotational axis of the green gear is displaced from the axis of the grey gear to give the constant 7.665. The orange arm attached to the green gear generates the term 9.665 Sin(2B). It rotates twice per year. The length of the arm contributes +/- 0.665 seconds per year on the dial. The blue gear generates the term 0.31 Cos(2C). There is a pin on the blue gear that engages a slot in the light grey lever that produces a rocking motion of the red gear. The red gear and the grey gear share a common axis but are not connected. In the Rittenhouse clock the point at the end of the orange lever is a pin that engages a horizontal rack that also rotates a gear with a pointer to show the equation of time. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/19/14 9:40 AM, David J Taylor wrote: From: Jim Lux Right now, the EOT is changing almost 30 seconds/day, which implies that the clock could be some seconds off during part of the day (although true at noon). [] 30 seconds/day? http://www.sundials.co.uk/pix/c/eot3.gif from: http://www.sundials.co.uk/equation.htm http://www.wsanford.com/~wsanford/exo/sundials/equation_of_time.html 5 Jan 5.2 minutes 6 Jan 5.7 minutes 30 seconds in a day.. The total variation over the year is +/- 15 minutes, but the derivative is a lot bigger at some times of the year (now) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 01/19/2014 05:46 PM, Poul-Henning Kamp wrote: In message 52dbff99.3060...@rubidium.dyndns.org, Magnus Danielson writes: My feverish brain now cranks out that all we need is a electromechanical WWVB receiver, thus no active electronic parts. That would be a nice little challenge. The main challenge is an antenna which delivers sufficient power. I don't know the WWVB signal well enough, but decoding DCF77 by mechanical means wouldn't be too hard. Amplification would indeed be the challenge, even if you live down the road from WWVB like some here do. Here we would need to do MSF or DCF77, both would be severly challenging to do passively. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Given the relatively low currents needed by the clock motor, and the relatively high currents that can be sourced/sinked by the arduino, and the fact that the motor winding is floating relative to the arduino, one could probably connect the motor like this: D0---SomeResistor--MOTOR-D1 Then, how to describe the way to drive it? Well, starting out with D0=D1=0, Set D1=1, then in 0.1 sec set D0=1. Wait 0.9 sec then: Set D0=0, then in 0.1 sec set D1=0... Wait 0.9 sec then: wash rinse repeat... -Chuck Harris Jim Lux wrote: On 1/19/14 9:17 AM, Chuck Harris wrote: The usual quartz clock that runs off of a AA cell is a little trickier to drive than you might think. You need to feed its stepper motor coil with an alternating +1.5V and -1.5V pulse. The pulse follows the rising or trailing edge of a 1/2 Hz square wave. I have driven them using a series capacitor and resistor to ground...arranged as a differentiator, but I don't recall the part values anymore. You arduino could certainly be made to generate such a pulse using a couple of resistors and a couple of digital outputs in a simple DAC sort of circuit. Yeah.. that *is* the challenge. Use two outputs and make a sort of H bridge ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
In message 52dc152f.6080...@rubidium.dyndns.org, Magnus Danielson writes: Here we would need to do MSF or DCF77, both would be severly challenging to do passively. Not decoding wise. Once you have a robust signal, it's easy... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Hi I’d bet that you can do some sort of simple fit to +/- 3 days from today and get a reasonable estimate of the rate. Exactly what you would fit might vary over the year. Bob On Jan 19, 2014, at 1:05 PM, Jim Lux jim...@earthlink.net wrote: On 1/19/14 9:40 AM, David J Taylor wrote: From: Jim Lux Right now, the EOT is changing almost 30 seconds/day, which implies that the clock could be some seconds off during part of the day (although true at noon). [] 30 seconds/day? http://www.sundials.co.uk/pix/c/eot3.gif from: http://www.sundials.co.uk/equation.htm http://www.wsanford.com/~wsanford/exo/sundials/equation_of_time.html 5 Jan 5.2 minutes 6 Jan 5.7 minutes 30 seconds in a day.. The total variation over the year is +/- 15 minutes, but the derivative is a lot bigger at some times of the year (now) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Jim: I used a simple f/f, q and ~q and 180 ohm resistors. Could easily be done with two ard outputs. needs 1/2 sec cycle. i just disconnected the coils from the epoxied blob with the clock electronics. You can also drive it backwards if it amuses. . . Don -- The power of accurate observation is commonly called cynicism by those who have not got it. -George Bernard Shaw Dr. Don Latham AJ7LL Six Mile Systems LLC 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/19/14 10:11 AM, Chuck Harris wrote:
Given the relatively low currents needed by the clock
motor, and the relatively high currents that can be
sourced/sinked by the arduino, and the fact that the
motor winding is floating relative to the arduino,
one could probably connect the motor like this:
D0---SomeResistor--MOTOR-D1
Then, how to describe the way to drive it?
Well, starting out with D0=D1=0,
Set D1=1, then in 0.1 sec set D0=1.
Wait 0.9 sec then:
Set D0=0, then in 0.1 sec set D1=0...
Wait 0.9 sec then:
wash rinse repeat...
That's what I'm going to try.
Actually, on an arduino, you can set the output pin to Hi Z..
So it's more like
#define PulseLength1 100// milliseconds
#define PulseLength2 100
void ClockTick(){
digitalWrite(D0,LOW); //preload the bits
digitalWrite(D1,HIGH);
pinMode(D0,OUTPUT); // now make them an output
pinMode(D1,OUTPUT);
delay(PulseLength1);// wait til pulse first part
digitalWrite(D0,HIGH); // flip direction
digitalWrite(D1,LOW);
delay(PulseLength2);// wait til second part
pinMode(D0,INPUT); // turn off pulse
pinMode(D1,INPUT);
}
That way you're not drawing power most of the time..
-Chuck Harris
Jim Lux wrote:
On 1/19/14 9:17 AM, Chuck Harris wrote:
The usual quartz clock that runs off of a AA cell is a little
trickier to drive than you might think. You need to feed
its stepper motor coil with an alternating +1.5V and -1.5V pulse.
The pulse follows the rising or trailing edge of a 1/2 Hz square
wave. I have driven them using a series capacitor and resistor
to ground...arranged as a differentiator, but I don't recall the
part values anymore.
You arduino could certainly be made to generate such a pulse using
a couple of resistors and a couple of digital outputs in a simple
DAC sort of circuit.
Yeah.. that *is* the challenge.
Use two outputs and make a sort of H bridge
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Re: [time-nuts] Local Solar Time Clock
On 1/19/14 10:47 AM, Don Latham wrote: Jim: I used a simple f/f, q and ~q and 180 ohm resistors. Could easily be done with two ard outputs. needs 1/2 sec cycle. i just disconnected the coils from the epoxied blob with the clock electronics. You can also drive it backwards if it amuses. . . Don Does it need any biphase pulse, or does it really need to be 500 ms pos and 500 ms neg? If it's 500/500, then I'll change my code to count half seconds instead of seconds... it's cleaner. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Yeah.. that *is* the challenge. Use two outputs and make a sort of H bridge Jim, No problem. 1) equation of time: See www.leapsecond.com/tools/eot1.c, source code that generates the equation of time and its derivative. Sample output attached. You can see the time varies from about -14 minutes to +16 minutes. The clock rate varies from -28 seconds to +22 seconds per day, which is about -324 ppm to +262 ppm. This is easy to do with leap cycles on a microcontroller. See my sidereal PIC code for an example: http://leapsecond.com/pic/src/pd28.asm 2) quartz clock stepper motor: For waveforms of a typical quartz clock see PDF page 13-17 of http://leapsecond.com/ten/clock-powers-of-ten-tvb.pdf See http://leapsecond.com/tools/comtick.c for an example of a PC program that drives a quartz clock stepper motor from a serial port. When driving a quartz clock stepper motor from a microcontroller, the trick I use is to configure two pins as *input* (tristate), and set output latches to 0 and 1. Then once a second all you do is change the mode to *output* for 50 ms. During the 950 ms idle time, XOR the two output latches with 11. That way you get the identical waveform as seen in the oscilloscope trace above. Pick current limiting resistors such that the clock ticks confidently but not violently. /tvbDaily Time and Rate Offsets -- Equation of Time day minutes rate offset rate offset PIC cycles 1 -2.904169 -0.450711 m/d -313.0 ppm -782 PIC 2 -3.351037 -0.446868 m/d -310.3 ppm -776 PIC 3 -3.793645 -0.442608 m/d -307.4 ppm -768 PIC 4 -4.231582 -0.437936 m/d -304.1 ppm -760 PIC 5 -4.664440 -0.432858 m/d -300.6 ppm -751 PIC 6 -5.091819 -0.427379 m/d -296.8 ppm -742 PIC 7 -5.513326 -0.421507 m/d -292.7 ppm -732 PIC 8 -5.928573 -0.415247 m/d -288.4 ppm -721 PIC 9 -6.337181 -0.408608 m/d -283.8 ppm -709 PIC 10 -6.738777 -0.401597 m/d -278.9 ppm -697 PIC 11 -7.132999 -0.394222 m/d -273.8 ppm -684 PIC 12 -7.519491 -0.386492 m/d -268.4 ppm -671 PIC 13 -7.897907 -0.378416 m/d -262.8 ppm -657 PIC 14 -8.267910 -0.370003 m/d -256.9 ppm -642 PIC 15 -8.629172 -0.361262 m/d -250.9 ppm -627 PIC 16 -8.981377 -0.352205 m/d -244.6 ppm -611 PIC 17 -9.324217 -0.342840 m/d -238.1 ppm -595 PIC 18 -9.657397 -0.333180 m/d -231.4 ppm -578 PIC 19 -9.980631 -0.323234 m/d -224.5 ppm -561 PIC 20 -10.293646 -0.313015 m/d -217.4 ppm -543 PIC 21 -10.596179 -0.302533 m/d -210.1 ppm -525 PIC 22 -10.887981 -0.291802 m/d -202.6 ppm -507 PIC 23 -11.168814 -0.280832 m/d -195.0 ppm -488 PIC 24 -11.438451 -0.269637 m/d -187.2 ppm -468 PIC 25 -11.696679 -0.258229 m/d -179.3 ppm -448 PIC 26 -11.943300 -0.246621 m/d -171.3 ppm -428 PIC 27 -12.178125 -0.234825 m/d -163.1 ppm -408 PIC 28 -12.400982 -0.222856 m/d -154.8 ppm -387 PIC 29 -12.611709 -0.210727 m/d -146.3 ppm -366 PIC 30 -12.810160 -0.198451 m/d -137.8 ppm -345 PIC 31 -12.996202 -0.186043 m/d -129.2 ppm -323 PIC 32 -13.169717 -0.173515 m/d -120.5 ppm -301 PIC 33 -13.330599 -0.160882 m/d -111.7 ppm -279 PIC 34 -13.478757 -0.148158 m/d -102.9 ppm -257 PIC 35 -13.614115 -0.135358 m/d -94.0 ppm -235 PIC 36 -13.736609 -0.122494 m/d -85.1 ppm -213 PIC 37 -13.846192 -0.109583 m/d -76.1 ppm -190 PIC 38 -13.942830 -0.096638 m/d -67.1 ppm -168 PIC 39 -14.026503 -0.083673 m/d -58.1 ppm -145 PIC 40 -14.097205 -0.070702 m/d -49.1 ppm -123 PIC 41 -14.154945 -0.057741 m/d -40.1 ppm -100 PIC 42 -14.199748 -0.044802 m/d -31.1 ppm-78 PIC 43 -14.231649 -0.031901 m/d -22.2 ppm-55 PIC 44 -14.250700 -0.019052 m/d -13.2 ppm-33 PIC 45 -14.256968 -0.006267 m/d-4.4 ppm-11 PIC 46 -14.250531 0.006437 m/d 4.5 ppm 11 PIC 47 -14.231482 0.019049 m/d13.2 ppm 33 PIC 48 -14.199929 0.031553 m/d21.9 ppm 55 PIC 49 -14.155992 0.043937 m/d30.5 ppm 76 PIC 50 -14.099804 0.056188 m/d39.0 ppm 98 PIC 51 -14.031513 0.068291 m/d47.4 ppm119 PIC 52 -13.951279 0.080234 m/d55.7 ppm139 PIC 53 -13.859274 0.092005 m/d63.9 ppm160 PIC 54 -13.755683 0.103591 m/d71.9 ppm180 PIC 55 -13.640705 0.114979 m/d79.8 ppm200 PIC 56 -13.514548 0.126157 m/d87.6 ppm219 PIC 57 -13.377434 0.137114 m/d95.2 ppm238 PIC 58 -13.229595 0.147839 m/d 102.7 ppm257 PIC 59 -13.071276 0.158319 m/d 109.9 ppm275 PIC 60 -12.902732 0.168544 m/d 117.0 ppm293 PIC 61 -12.724227 0.178505 m/d 124.0 ppm310 PIC 62 -12.536038 0.188189 m/d 130.7 ppm327 PIC 63 -12.338450 0.197588 m/d 137.2 ppm343 PIC 64 -12.131758 0.206692 m/d 143.5 ppm359 PIC 65 -11.916266 0.215492 m/d 149.6 ppm
Re: [time-nuts] Local Solar Time Clock
Hi I’d put the table(s) in flash. You aren’t going to change it often enough to matter in terms of re-flash cycles. They would all be pre-calculated for that clock at that location, starting from today. In my approach this would be a very application specific shoot of the code. The 18F24J10 is $1.66 in the cheapest package. No combination of package and temp range is over $2 in quantity one. It’s got 16K flash and way more of everything else you probably would need. There are other parts from other vendors that are also under $2 that might make more sense. The cost of the pc board to mount everything on will probably be the biggest chunk of your BOM. Bob On Jan 19, 2014, at 2:09 PM, Tom Van Baak t...@leapsecond.com wrote: Even a small PIC has room for a fairly large table. The EEPROM on the 8-pin PIC12F chips I use is just 256 bytes. Then again, I'm not sure what you mean by small PIC or fairly large. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/19/14 11:21 AM, Tom Van Baak wrote: Yeah.. that *is* the challenge. Use two outputs and make a sort of H bridge Jim, No problem. 1) equation of time: See www.leapsecond.com/tools/eot1.c, source code that generates the equation of time and its derivative. Sample output attached. You can see the time varies from about -14 minutes to +16 minutes. The clock rate varies from -28 seconds to +22 seconds per day, which is about -324 ppm to +262 ppm. This is easy to do with leap cycles on a microcontroller. See my sidereal PIC code for an example: http://leapsecond.com/pic/src/pd28.asm When driving a quartz clock stepper motor from a microcontroller, the trick I use is to configure two pins as *input* (tristate), and set output latches to 0 and 1. Then once a second all you do is change the mode to *output* for 50 ms. During the 950 ms idle time, XOR the two output latches with 11. Exactly what I was going to do.. That way you get the identical waveform as seen in the oscilloscope trace above. Pick current limiting resistors such that the clock ticks confidently but not violently. So it's one pulse per second, with the polarity alternating on each pulse... Easy enough.. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Local Solar Time Clock
I tried that algorithm and it did not seem to agree all that well with more sophisticated ones... This one seems to work better: http://www.astronomycorner.net/games/analemma.c -- See www.leapsecond.com/tools/eot1.c, source code that generates the equation of time and its derivative ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/19/14 11:24 AM, Bob Camp wrote: Hi I’d put the table(s) in flash. You aren’t going to change it often enough to matter in terms of re-flash cycles. They would all be pre-calculated for that clock at that location, starting from today. In my approach this would be a very application specific shoot of the code. The 18F24J10 is $1.66 in the cheapest package. No combination of package and temp range is over $2 in quantity one. It’s got 16K flash and way more of everything else you probably would need. There are other parts from other vendors that are also under $2 that might make more sense. For me time is money.. so I'm willing to invest $30 in an arduino at the local radio shack and call it done. If it were a product one were selling, then, yes.. program a PIC, etc. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
What is the difference in rate between solar and UTC and how much does the solar rate change from week to week? I know the theory and to get it nearly perfect you'd need a computer. But if your tolerance is only that it be good enough for a visual reference. (remember he said __NO SOFTWARE__) So we are talking about mechanical hands on a clock face. So there is some acceptable error. Do we only need to keep solar time to within a minute per day? Even computer display does NOT need to be time nut level accurate because the monitor has a finite refresh frequency. The screen cannot be drawn any faster than monitor frame rate which is going to be maybe 60Hz to 120Hz. So you can be off by on order of 0.01 seconds (A huge error by nuts standards) and no one would notice because of the quantization error of the frame rate. On Sun, Jan 19, 2014 at 4:25 AM, Tom Van Baak t...@leapsecond.com wrote: I wonder if you really need a special clock? Can't you adjust a normal spring driven clock to run fast (or is it slow?) by about 1/3 of a percent (one day per year)? This should be within the range of adjustment. Chris, When you mention 1/3 percent, you're thinking sidereal time, which is a completely different concept, and much easier to implement than equation of time. Sidereal time is simply a calendar-day independent, fixed (2730 ppm) frequency offset. I already have PIC chips that do this; see PD28 under www.leapsecond.com/pic/picdiv.htm or read the comments in the source code at: http://www.leapsecond.com/pic/src/pd28.asm Solar time, on the other hand, is continuously variable in rate (and phase) throughout the whole year. A microprocessor implementation of solar time also needs to know calendar date, time, and longitude. A 4800 baud GPS NMEA stream input would be a convenient way to obtain this information. Without using floating point or trig functions, a tiny PIC implementation would probably use a 365 entry lookup table to adjust the output tick rate on a per-day basis. A more capable Arduino or RPi might allow one to accurate calculate EOT directly from planetary motion equations, avoiding hard-coded tables altogether. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On Sun, Jan 19, 2014 at 6:32 AM, Charles Steinmetz csteinm...@yandex.comwrote: The question I haven't seen answered is what error band is acceptable to the OP. Mark has posted that it is not terribly difficult to get within small fractional minutes if you start with GPS time and position data, as he has done for a future release of LH. But getting to the millisecond level or better is likely much more difficult. What would you do with millisecond level timing? One can only draw to a computer monitor about 60 to 120 times per second at most. If the computer were driving a costom build LED numeric display it could write milliseconds but the human eye can not detect chances about about 100Hz Don't worry about fitting this inside a PIC, modern uPs have 32K of storage, can be programmed in C++, have floating point math libraries and cost $5 shipped for one mounted to a PCB with supporting electronics. Pro-Mini-atmega328-5V-16Mhttp://www.ebay.com/itm/New-Pro-Mini-atmega328-5V-16M-Replace-ATmega128-Arduino-Compatible-Nano-/200957063666?pt=LH_DefaultDomain_0hash=item2ec9f971f2 I'm using something like this for robot inverse kinematics, basically some linear algebra using 4x4 matrixes and it does it in real time with 3/4 of the memory unused. It is pretty easy to connect one of these to a small cell phone sized graphic screen. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
From: Jim Lux http://www.wsanford.com/~wsanford/exo/sundials/equation_of_time.html 5 Jan 5.2 minutes 6 Jan 5.7 minutes 30 seconds in a day.. The total variation over the year is +/- 15 minutes, but the derivative is a lot bigger at some times of the year (now) ___ Higher than I expected from a quick look at the graph. I had 17 minutes total variation in 6 months in my mind! Mind you, some figure in that table loom doubtful - Oct 01, 07, 13 - unless they are deliberately (and confusingly) missing out the - signs! Thanks. David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
My feverish brain now cranks out that all we need is a electromechanical WWVB receiver, thus no active electronic parts. That would be a nice little challenge. That could work. I remember seeing an only World War II vintage teletype machine. It would print test from an HF receiver. Given the technology of the day it had no software inside The way it would work is you spin a disk at a nominal one rev per second and disk has electrical contacts on it that make a bit stream. Phase lock that with WWVB. So you control the motor speed. Actually I think you'd be better off using the 60KHz carrier. Again limiting yourself to only 1940's technology, I think you could build a local oscillator that would phase lock to WWVB's carrier, and from there you control the motor speed and and then you use the spinning disk to decom the bits. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/19/14 12:20 PM, David J Taylor wrote: From: Jim Lux http://www.wsanford.com/~wsanford/exo/sundials/equation_of_time.html 5 Jan 5.2 minutes 6 Jan 5.7 minutes 30 seconds in a day.. The total variation over the year is +/- 15 minutes, but the derivative is a lot bigger at some times of the year (now) ___ Higher than I expected from a quick look at the graph. I had 17 minutes total variation in 6 months in my mind! So did I until I started coding it up... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 14-01-19 03:20 PM, Chris Albertson wrote: My feverish brain now cranks out that all we need is a electromechanical WWVB receiver, thus no active electronic parts. That would be a nice little challenge. That could work. I remember seeing an only World War II vintage teletype machine. It would print test from an HF receiver. Given the technology of the day it had no software inside The way it would work is you spin a disk at a nominal one rev per second and disk has electrical contacts on it that make a bit stream. Phase lock that with WWVB. So you control the motor speed. Actually I think you'd be better off using the 60KHz carrier. Again limiting yourself to only 1940's technology, I think you could build a local oscillator that would phase lock to WWVB's carrier, and from there you control the motor speed and and then you use the spinning disk to decom the bits. My first home personal computer (1964) was the Digi-Comp, no electricity, but definitely had software. Stored program, clock, display, conditionals... In the 1930s the Norden bomb-sight had software. The Jacquard loom had software. Perhaps the no software requirement should be refined. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Local Solar Time Clock
I am really learning a lot by reading the current discussion. As for accuracy, the clock was originally envisioned for non-scientific use. Something within the budget and building capabilities of the home enthusiast. A weekly deviation in seconds would seem tolerable. But I am encouraged those here will find the optimal solution. Once operational, it might be worthwhile to port the design to PIC and provide a graphical interface for entering location data during programming. There appear to be PC solar clock apps online against which one could periodically compare the quartz clock and correct any accumulated error. http://www.jgiesen.de/sunclock/index.html Can't wait to build one. P Nielsen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
I hope this thread dies here. In a message dated 1/19/2014 13:22:10 Pacific Standard Time, a...@comcast.net writes: On 14-01-19 03:20 PM, Chris Albertson wrote: My feverish brain now cranks out that all we need is a electromechanical WWVB receiver, thus no active electronic parts. That would be a nice little challenge. That could work. I remember seeing an only World War II vintage teletype machine. It would print test from an HF receiver. Given the technology of the day it had no software inside The way it would work is you spin a disk at a nominal one rev per second and disk has electrical contacts on it that make a bit stream. Phase lock that with WWVB. So you control the motor speed. Actually I think you'd be better off using the 60KHz carrier. Again limiting yourself to only 1940's technology, I think you could build a local oscillator that would phase lock to WWVB's carrier, and from there you control the motor speed and and then you use the spinning disk to decom the bits. My first home personal computer (1964) was the Digi-Comp, no electricity, but definitely had software. Stored program, clock, display, conditionals... In the 1930s the Norden bomb-sight had software. The Jacquard loom had software. Perhaps the no software requirement should be refined. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
FWIW If you take a cheap digital analog clock, remove the battery, connect to the two coil connections, you can drive the clock with a 0.5 Hz square wave through the series combination of a capacitor and resistor. Typical values are 100mfd and 200 ohms. You need to select these values to get certain stepping without pole-ing. The clock originally used 1.2 volt pulses, alternate polarity about 20 mS long. You can trade off these values and still get smooth certain operation. Cheers, Neville Michie ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Chris Albertson Don't worry about fitting this inside a PIC, modern uPs have 32K of storage, can be programmed in C++, have floating point math libraries and cost $5 shipped for one mounted to a PCB with supporting electronics. Pro-Mini-atmega328-5V-16Mhttp://www.ebay.com/itm/New-Pro-Mini-atmega328-5V-16M-Replace-ATmega128-Arduino-Compatible-Nano-/200957063666?pt=LH_DefaultDomain_0hash=item2ec9f971f2 And this lead me to a RTC module for $1.88 that will provide a time that can be massaged with eq'n of time. -- The power of accurate observation is commonly called cynicism by those who have not got it. -George Bernard Shaw Dr. Don Latham AJ7LL Six Mile Systems LLC 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
If you Really want to show it, use a pendulum clock using an equation of time cam to change the length? Don P Nielsen I am really learning a lot by reading the current discussion. As for accuracy, the clock was originally envisioned for non-scientific use. Something within the budget and building capabilities of the home enthusiast. A weekly deviation in seconds would seem tolerable. But I am encouraged those here will find the optimal solution. Once operational, it might be worthwhile to port the design to PIC and provide a graphical interface for entering location data during programming. There appear to be PC solar clock apps online against which one could periodically compare the quartz clock and correct any accumulated error. http://www.jgiesen.de/sunclock/index.html Can't wait to build one. P Nielsen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- The power of accurate observation is commonly called cynicism by those who have not got it. -George Bernard Shaw Dr. Don Latham AJ7LL Six Mile Systems LLC 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
At last, a use for all those devices with 2 second pulse output :-) Don Neville Michie FWIW If you take a cheap digital analog clock, remove the battery, connect to the two coil connections, you can drive the clock with a 0.5 Hz square wave through the series combination of a capacitor and resistor. Typical values are 100mfd and 200 ohms. You need to select these values to get certain stepping without pole-ing. The clock originally used 1.2 volt pulses, alternate polarity about 20 mS long. You can trade off these values and still get smooth certain operation. Cheers, Neville Michie ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- The power of accurate observation is commonly called cynicism by those who have not got it. -George Bernard Shaw Dr. Don Latham AJ7LL Six Mile Systems LLC 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
And this lead me to a RTC module for $1.88 that will provide a time that can be massaged with eq'n of time. Speaking of RTC modules, I don't know which one you found, but I have some of these on order for $2.29 each: http://www.ebay.com/itm/DS3231-AT24C32-IIC-Precision-RTC-Real-Time-Clock-Memory-Module-For-Arduino-/390734564207 It uses the same chip as the ChronoDot, which I bought one of months ago for $15. It also has an additional I2C EEPROM on board. If anyone is interested, I'll report back as to whether the Chinese modules are any good after I receive them. Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
An electro-mechanical RX for VLF. http://www.wireless.org.uk/mechrx.htm enjoy ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Hi: I thought that noon was defined as the Sun crossing the local meridian. So something like the Dent Dipleidoscope can be used to know the exact instant when that happens. This is different than standard time by the EOT. http://www.prc68.com/I/Dent.shtml It's not clear if the OP wants true local time or the time at the center of his time zone. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Many years ago I saw some pictures in Sky and Telescope where some people had mounted a camera in such a way as to not be disturbed from day to day and taken an exposure of the sun at 12 noon local mean time every day of the year all on the same photographic plate. At the end of the year upon development of the plate they had a nice infinity sign. I don't see how such a feet could be pulled off with digital photography. Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: Brian Lloyd br...@lloyd.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, January 19, 2014 7:35 AM Subject: Re: [time-nuts] Local Solar Time Clock On Sat, Jan 18, 2014 at 10:09 PM, David J Taylor david-tay...@blueyonder.co.uk wrote: I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. Is there a commercial product or kit available for this? For a mechanical clock, probably not. The problem is demonstrated by what I suggested that you do with a stick and pebbles. By marking the position of the sun to locate the point where the sun is highest in the sky you identify local solar noon. By marking the position of the sundial's shadow at a fixed time every day relative to GMT you will find that, over the course of a year, your shadow will inscribe an analemma, whose lateral displacement represents the correction factor between sidereal (GMT) noon and local solar noon. This is all caused by the tilt of the rotational axis of the earth which causes the poles to be displaced either advanced or retarded relative to the centroid at the equinoxes. (Equinoxae?) So your mechanical clock would need to speed up and slow down in a smooth fashion twice over the course of a year. Pretty hard to do with a mechanical clock. Definitely a job for a uP. BUT a really cool thing would be to interface a camera to find the point in time where YOUR local noon actually occurs and corrects the clock. Automatic meridian circle anyone? -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
analemma not infinity. Excuse the analism please. - Original Message - From: Max Robinson To: Discussion of precise time and frequency measurement Sent: Sunday, January 19, 2014 10:36 PM Subject: Re: [time-nuts] Local Solar Time Clock Many years ago I saw some pictures in Sky and Telescope where some people had mounted a camera in such a way as to not be disturbed from day to day and taken an exposure of the sun at 12 noon local mean time every day of the year all on the same photographic plate. At the end of the year upon development of the plate they had a nice infinity sign. I don't see how such a feet could be pulled off with digital photography. Regards. Max. K 4 O DS. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Digital photography - use Photoshop …. On Jan 19, 2014, at 10:49 PM, quartz55 quart...@hughes.net wrote: analemma not infinity. Excuse the analism please. - Original Message - From: Max Robinson To: Discussion of precise time and frequency measurement Sent: Sunday, January 19, 2014 10:36 PM Subject: Re: [time-nuts] Local Solar Time Clock Many years ago I saw some pictures in Sky and Telescope where some people had mounted a camera in such a way as to not be disturbed from day to day and taken an exposure of the sun at 12 noon local mean time every day of the year all on the same photographic plate. At the end of the year upon development of the plate they had a nice infinity sign. I don't see how such a feet could be pulled off with digital photography. Regards. Max. K 4 O DS. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
It's not clear if the OP wants true local time or the time at the center of his time zone. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html My original idea was to have 12 noon equate to the sun's highest position in the sky at my locality, and remain so reliably throughout the year. There is obviously some very specialized talent in this group, and I would have trouble following all the suggestions so far. I hope one of the outcomes of this thread will be a timepiece that a moderately skilled electronics hobbyist can replicate. For example, I can program PIC's and build circuits, but not write code. Anything electromechanical is fine. A one-off solution created in a well-equipped lab as a curiosity piece would probably not be within my resources. I had originally imagined something like a PIC coded to deliver modified pulses to a wall clock module. Is it possible to arrive at anything close to that level of simplicity? For my use, this was not intended to be a research grade instrument. P Nielsen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/19/14 8:00 PM, P Nielsen wrote: It's not clear if the OP wants true local time or the time at the center of his time zone. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html My original idea was to have 12 noon equate to the sun's highest position in the sky at my locality, and remain so reliably throughout the year. There is obviously some very specialized talent in this group, and I would have trouble following all the suggestions so far. I hope one of the outcomes of this thread will be a timepiece that a moderately skilled electronics hobbyist can replicate. For example, I can program PIC's and build circuits, but not write code. Anything electromechanical is fine. A one-off solution created in a well-equipped lab as a curiosity piece would probably not be within my resources. I had originally imagined something like a PIC coded to deliver modified pulses to a wall clock module. Is it possible to arrive at anything close to that level of simplicity? For my use, this was not intended to be a research grade instrument. Most certainly... Having got most of the way through it, it turns out that some of the trickier areas are user interface... A regular old wall clock has a knob on the back to set the time. BUT, for the solar clock you need to tell it: 1) your longitude 2) What time and date it is (in either local solar time, or in standard time) In a mechanical clock, you'd probably set the month and day somehow on a dial, and deal with the longitude offset by just applying a fixed offset from local standard time (e.g. I'm at 119W, so I'd set the clock 4 minutes fast, because my time zone's meridian is at 120W, so noon happens 4 minutes earlier for me) My going in solution is that you do that with a serial connection (via USB) and some simple commands. The vanilla Arduino Uno has a USB connector on it, so it's pretty easy to use. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
There is digital astronomy specific out there that will overlay/digitally add multiple images, do filtering, enhance contrast, etc. It's just something I've read about at this point. I haven't used it and couldn't point you to specific software. From: quartz55 quart...@hughes.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, January 19, 2014 9:49 PM Subject: Re: [time-nuts] Local Solar Time Clock analemma not infinity. Excuse the analism please. - Original Message - From: Max Robinson To: Discussion of precise time and frequency measurement Sent: Sunday, January 19, 2014 10:36 PM Subject: Re: [time-nuts] Local Solar Time Clock Many years ago I saw some pictures in Sky and Telescope where some people had mounted a camera in such a way as to not be disturbed from day to day and taken an exposure of the sun at 12 noon local mean time every day of the year all on the same photographic plate. At the end of the year upon development of the plate they had a nice infinity sign. I don't see how such a feet could be pulled off with digital photography. Regards. Max. K 4 O DS. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
m...@maxsmusicplace.com said: had mounted a camera in such a way as to not be disturbed from day to day and taken an exposure of the sun at 12 noon local mean time every day of the year all on the same photographic plate. At the end of the year upon development of the plate they had a nice infinity sign. I don't see how such a feet could be pulled off with digital photography. How about something like a digital camera with a USB setup. Mount the camera pointed at the noon sun. Plug the USB stuff into a PC. Each Noon, have the PC tell it to take a picture. (That probably restricts your choice of cameras. Or use a webcam with a LED in the corner connected to a PPS for accurate timing...) After a year, merge the pictures together. SMOP. :) -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Local Solar Time Clock
I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. Is there a commercial product or kit available for this? Thank you for any suggestions. P Nielsen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/18/14 2:25 PM, P Nielsen wrote: I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. So it needs to take into account the equation of time? there's probably some exotic all mechanical geared scheme for this in some $20k pocket watch.. Is there a commercial product or kit available for this? I know you're not interested in a software solution, but my approach would be to drive a conventional electric clock (1pps ticks) with some logic that implements the equation of time. It would be pretty easy to have a table that sets the divisor from the clock to the 1pps and slowly changes it above and below the nominal rate so that the clock reads noon at solar noon. I did it back in 2004 using a HP 3325 replacing the 32 kHz crystal in a 24 Hr clock to build a Mars clock. It kind of depends on what instantaneous accuracy you need, too. the deviation is on the order of 15 minutes, but do you want the error of your clock to be a maximum of 1 second or 10 seconds or what... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
VCR's were well known to reliably read 12:00 throughout the year... Do you want to make or buy? Using a microprocessor, it's easy to drive a stepper-motor based wall clock at slight offsets from true 32 kHz or 1 Hz rate. Converting UTC/1PPS to solar rate and time for your given location and time of year is easy with an Arduino or RPi. You can double check the clock with a sundial. Add NTP and DUT1 corrections for sub-second accuracy. Add GPS if you want the clock to self-adjust when moved east or west (noon moves a couple of milliseconds per meter). This feature would be especially cool if the clock were used in a vehicle. /tvb (i5s) On Jan 18, 2014, at 2:25 PM, P Nielsen pniel...@tpg.com.au wrote: I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. Is there a commercial product or kit available for this? Thank you for any suggestions. P Nielsen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/18/14 2:25 PM, P Nielsen wrote: I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. Is there a commercial product or kit available for this? http://en.wikipedia.org/wiki/Equation_clock so what you're looking for is an Equation Clock.. There's examples referenced in the wikipedia article in the British Museum. The article also describes some of the ways of doing it. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Small brass cannon. Use a small telescope pointed at the sun at transit, with the output side focused on the fuse. Loud bang ,.. it's 12:00 o'clock. -- FL On Saturday, January 18, 2014 4:23 PM, Tom Van Baak (lab) t...@leapsecond.com wrote: VCR's were well known to reliably read 12:00 throughout the year... Do you want to make or buy? Using a microprocessor, it's easy to drive a stepper-motor based wall clock at slight offsets from true 32 kHz or 1 Hz rate. Converting UTC/1PPS to solar rate and time for your given location and time of year is easy with an Arduino or RPi. You can double check the clock with a sundial. Add NTP and DUT1 corrections for sub-second accuracy. Add GPS if you want the clock to self-adjust when moved east or west (noon moves a couple of milliseconds per meter). This feature would be especially cool if the clock were used in a vehicle. /tvb (i5s) On Jan 18, 2014, at 2:25 PM, P Nielsen pniel...@tpg.com.au wrote: I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. Is there a commercial product or kit available for this? Thank you for any suggestions. P Nielsen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
HI If noon is the point you are concerned about, and it’s a fixed location, a fairly simple set of tables in a micro should do the trick. Past that it’s a selection for the time base, anything from a 555 timer through Cesium and / or GPS could be used. Even with a table, the deviation during the day could be pretty low relative to the hands moving on a clock face. Bob On Jan 18, 2014, at 7:25 PM, Jim Lux jim...@earthlink.net wrote: On 1/18/14 2:25 PM, P Nielsen wrote: I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. Is there a commercial product or kit available for this? http://en.wikipedia.org/wiki/Equation_clock so what you're looking for is an Equation Clock.. There's examples referenced in the wikipedia article in the British Museum. The article also describes some of the ways of doing it. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/18/14 4:22 PM, Tom Van Baak (lab) wrote: Add GPS if you want the clock to self-adjust when moved east or west (noon moves a couple of milliseconds per meter). This feature would be especially cool if the clock were used in a vehicle. Ooohh... an automatic self adjusting sundial for boats, planes, automobiles... It will become a must have for every megayacht. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/18/14 2:25 PM, P Nielsen wrote: I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. Once you buy into a microprocessor, it's pretty easy to make all sorts of clocks.. When I built the Mars clock, I also thought about how cool it would be to building a clock that reads 6 at sunset and sunrise, 12 at noon/midnight, or, for that matter, using conventional analog clocks as the display device for relative positions of astronomical bodies (e.g. moon, planets) Sort of a locally centered orrery. I've also contemplated building a satellite pass clock (as opposed to displaying it on the usual screen display). Over the years I've had opportunity to care about when a particular satellite was above the horizon and where it was in the sky, and some sort of at a glance display would have been useful. For example, last year I was doing some experiments with measuring radio propagation from the ground to a radio on ISS, so there was a whole get ready for the measurement, ok, it should be over the horizon now, etc. And you're doing this outdoors in bright sunlight, and it would have been handy to have a big analog dial to look at (like the start clock in some races) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
http://www.precisionsundials.com The sawyer looks like it fits the bill. $8,000 Sent from mobile On Jan 18, 2014, at 4:25 PM, P Nielsen pniel...@tpg.com.au wrote: I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. Is there a commercial product or kit available for this? Thank you for any suggestions. P Nielsen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/18/14 5:11 PM, Bill Dailey wrote: http://www.precisionsundials.com The sawyer looks like it fits the bill. $8,000 Actually, only $2,100.. that fancy helical thing Renaissance was the 8 kilobuck one.. The Sawyer thing has a lot of nice design features. Very clever how they do the equation of time compensation, and I like the wedge. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Local Solar Time Clock
Lady Heather can display time in LMST/LAST/GMST/GAST I made a version that has an option to just show the date/time in full screen mode for Jim Lux/JPL but never heard back from him. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
Some time ago I found this - a small algorithm implemented in MSP430 with photoresistor to synchronise with the sun. Search for Intelligent Dusk/Dawn Light Sensor Richard S. LaBarbera. Of couse, you asked for a true hardware solution, but maybe this is interesting for you. Matthias ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On 1/18/14 5:23 PM, Mark Sims wrote: Lady Heather can display time in LMST/LAST/GMST/GAST I made a version that has an option to just show the date/time in full screen mode for Jim Lux/JPL but never heard back from him. I have passed it on to the person who was asking about it..I'll have to go over and see what happened. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Local Solar Time Clock
Thank you for the suggestions so far. When I said no software, I meant not something like this: http://www.jgiesen.de/sunmoonclock/index.html I was hoping someone here might have come up with a cheap quartz clock driven by a microprocessor, and the necessary code. That would seem to be the most practical solution. Anyone? P Nielsen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Local Solar Time Clock
http://www.pendulumofmayfair.co.uk/view.asp?pid=272cat=Longcase%20Clocks ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
On Sat, Jan 18, 2014 at 2:25 PM, P Nielsen pniel...@tpg.com.au wrote: I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. Put a stick vertically in the ground. Once a week place pebbles along the tip of the shadow of the stick from about 11AM until about 1PM *standard* time (not daylight savings time). Find which pebble is closest to the stick and leave it there, removing all other pebbles. Repeat for a year. At that point in time you will have a collection of pebbles that describes a figure '8' (an Analemma). Label the each pebble with the date. Now you can find local solar noon very accurately. -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
How about a Fred Flintstone wrist sundial? :-) Isn't that what he wore in the cartoon? Actually, the idea of a sundial clock that was mobile sounds pretty cool. Joe Gray W5JG On Sat, Jan 18, 2014 at 5:55 PM, Jim Lux jim...@earthlink.net wrote: On 1/18/14 4:22 PM, Tom Van Baak (lab) wrote: Add GPS if you want the clock to self-adjust when moved east or west (noon moves a couple of milliseconds per meter). This feature would be especially cool if the clock were used in a vehicle. Ooohh... an automatic self adjusting sundial for boats, planes, automobiles... It will become a must have for every megayacht. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
I'm working on it now. Got the arduino UNO, need to go get a cheap cook tomorrow On Jan 18, 2014, at 18:01, P Nielsen pniel...@tpg.com.au wrote: Thank you for the suggestions so far. When I said no software, I meant not something like this: http://www.jgiesen.de/sunmoonclock/index.html I was hoping someone here might have come up with a cheap quartz clock driven by a microprocessor, and the necessary code. That would seem to be the most practical solution. Anyone? P Nielsen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. Is there a commercial product or kit available for this? Thank you for any suggestions. P Nielsen == If you have an iPad, consider Emerald Observatory: http://www.emeraldsequoia.com/eo/ which includes the equation of time offset. May not do exactly what you want, but you will have lots of fun! Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
-Original Message- From: Jim Lux Actually, only $2,100.. that fancy helical thing Renaissance was the 8 kilobuck one.. The Sawyer thing has a lot of nice design features. Very clever how they do the equation of time compensation, and I like the wedge. = .. but useless here at 56 degrees N! G Also useless on cloudy days. David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Local Solar Time Clock
I just added a equation-of-time routine to the next release of Lady Heather. ..It can offset the time display by the Equation of Time. The calculated offset seems to agree rather well (like around 0.01 minutes) with the one on the NOAA website. It could be made a little better, but that would take more than a little work. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
ll the solutions proposed so far don' meet the criterion that the clock not be software. It's too esy to make a software display. yu just start with UTC and apply a formula from an amanac. But what was requested was something made with gears and springs I wonder if you really need a special clock? Can't you adjust a normal spring driven clock to run fast (or is it slow?) by about 1/3 of a percent (one day per year)? This should be within the range of adjustment. So take a normal clock and go outdoors at noon and look at your sundial. Set the clock to 12:00 at local noon. Then the next day check again and adjust the lever on the rear of the clock to make it go faster or slower. After a few days it should work. On Sat, Jan 18, 2014 at 10:09 PM, David J Taylor david-tay...@blueyonder.co.uk wrote: I am looking for a physical clock (not software) that will indicate local solar time. IOW when the sun is at its highest point, the clock would reliably read 12:00 throughout the year. Is there a commercial product or kit available for this? Thank you for any suggestions. P Nielsen == If you have an iPad, consider Emerald Observatory: http://www.emeraldsequoia.com/eo/ which includes the equation of time offset. May not do exactly what you want, but you will have lots of fun! Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Local Solar Time Clock
From: Chris Albertson ll the solutions proposed so far don' meet the criterion that the clock not be software. It's too esy to make a software display. yu just start with UTC and apply a formula from an amanac. But what was requested was something made with gears and springs I wonder if you really need a special clock? Can't you adjust a normal spring driven clock to run fast (or is it slow?) by about 1/3 of a percent (one day per year)? This should be within the range of adjustment. So take a normal clock and go outdoors at noon and look at your sundial. Set the clock to 12:00 at local noon. Then the next day check again and adjust the lever on the rear of the clock to make it go faster or slower. After a few days it should work. Are you perhaps thinking of sidereal time, Chris? David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
