JL
Jim Lux
Sun, Jan 19, 2014 7:02 PM
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.
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.
TV
Tom Van Baak
Sun, Jan 19, 2014 7:21 PM
Yeah.. that is the challenge.
Use two outputs and make a sort of "H bridge"
Jim,
No problem.
- 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
- 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.
/tvb
> 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.
/tvb
JL
Jim Lux
Sun, Jan 19, 2014 7:28 PM
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.
- 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..
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..
DJ
David J Taylor
Sun, Jan 19, 2014 8:20 PM
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-taylor@blueyonder.co.uk
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-taylor@blueyonder.co.uk
JL
Jim Lux
Sun, Jan 19, 2014 8:26 PM
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...
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...
TV
Tom Van Baak
Sun, Jan 19, 2014 9:22 PM
Higher than I expected from a quick look at the graph. I had 17 minutes
total variation in 6 months in my mind!
David,
Treating solar time as an hourly time/frequency reference over one year, attached are:
- eot-phase.gif -- phase plot (time error); the usual equation-of-time plot you see everywhere.
- eot-freq.gif -- frequency plot, essentially the variation in length of "solar second".
- eot-adev.gif -- the ADEV of a clock keeping solar time.
This data came from http://leapsecond.com/tools/eot2.c (I agree there are more complex and more accurate equation of time calculations, but this is good enough for ADEV).
/tvb
> Higher than I expected from a quick look at the graph. I had 17 minutes
> total variation in 6 months in my mind!
David,
Treating solar time as an hourly time/frequency reference over one year, attached are:
1) eot-phase.gif -- phase plot (time error); the usual equation-of-time plot you see everywhere.
2) eot-freq.gif -- frequency plot, essentially the variation in length of "solar second".
3) eot-adev.gif -- the ADEV of a clock keeping solar time.
This data came from http://leapsecond.com/tools/eot2.c (I agree there are more complex and more accurate equation of time calculations, but this is good enough for ADEV).
/tvb
NM
Neville Michie
Sun, Jan 19, 2014 9:35 PM
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
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
DL
Don Latham
Sun, Jan 19, 2014 11:13 PM
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
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
BC
Brooke Clarke
Mon, Jan 20, 2014 2:26 AM
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
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
