Re: [time-nuts] Sidereal timekeeping
I am quite aware of the fact that quartz clocks and watches drive their movements directly from their supplies with tailored pulses. What I said was that a 0.5 Hz square-wave from a logic source will drive these movements if you select appropriate values of series capacitor and resistor. Not everyone has acquired the training to use microprocessors, which are becoming a blight on the electronics world by being a cheap way of making insupportable and undocumented devices that cannot be repaired or adjusted. The engineering that is invested in these devices does nothing to enhance the traditional step by step evolution that was a characteristic of electronic technology. You cannot see a bright idea that another has developed and take it one step further. You have a black box and when it dies you will be none the wiser, so you will design your own and make the same mistakes that were in the original. cheers, Neville Michie On 19/05/2011, at 9:35 PM, Chuck Harris wrote: An actual quartz analog wristwatch wouldn't do something so mundane as to use a 50uf capacitor to drive the coils. They do this: DRIVER-A-COIL-+ ..| DRIVER-B--+ And feed the drivers with these waveforms: 1.5V..+-+.+-+.+-+.. ..|.|.|.|.|.|.. A-+ +-+ +-+ +---... 1.5V..+-+.+-+.+-+.. ..|.|.|.|.|.|.. B-+ +-+ +-+ +---... Where the pulses alternately come from A and B every second. If you use a PIC to drive the clock, the driver is easy to program in software. -Chuck Harris iov...@inwind.it wrote: I understand now why most analog wristwatches do tick every two seconds when the battery is low. I believed the logic used this trick to signal low battery. Antonio I8IOV ___ 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] Sidereal timekeeping
Hi Bob, Certainly! Silicon and programming is so cheap that you can do wonderful things in tiny little spaces that takes virtually no power to run. A 12 pin PIC microprocessor could easily add that level of control to such a clock or watch motor driver. I stopped looking at analog quartz wristwatches when they were in the driving generation I described below. I would be shocked if there hadn't been an order of magnitude improvement since then. My personal preference is for highly jeweled totally mechanical automatic winding wristwatches. My hobby compels me to have high accuracy time and frequency around, but my life just doesn't run with that kind of precision. -Chuck Harris Bob Camp wrote: Hi If you dig into the data sheets on modern watch driver IC's they get pretty crazy with the drive waveforms. They do a PWM / switcher like sequence on each drive pulse and look at the current in the coil. The objective is to just barely put in enough power to supply the torque required. Bob On May 19, 2011, at 7:35 AM, Chuck Harris wrote: An actual quartz analog wristwatch wouldn't do something so mundane as to use a 50uf capacitor to drive the coils. They do this: DRIVER-A-COIL-+ ..| DRIVER-B--+ And feed the drivers with these waveforms: 1.5V..+-+.+-+.+-+.. ..|.|.|.|.|.|.. A-+ +-+ +-+ +---... 1.5V..+-+.+-+.+-+.. ..|.|.|.|.|.|.. B-+ +-+ +-+ +---... Where the pulses alternately come from A and B every second. If you use a PIC to drive the clock, the driver is easy to program in software. -Chuck Harris iov...@inwind.it wrote: I understand now why most analog wristwatches do tick every two seconds when the battery is low. I believed the logic used this trick to signal low battery. Antonio I8IOV ___ 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] Sidereal timekeeping
Hi If you dig into the data sheets on modern watch driver IC's they get pretty crazy with the drive waveforms. They do a PWM / switcher like sequence on each drive pulse and look at the current in the coil. The objective is to just barely put in enough power to supply the torque required. Bob On May 19, 2011, at 7:35 AM, Chuck Harris wrote: > An actual quartz analog wristwatch wouldn't do something so mundane as > to use a 50uf capacitor to drive the coils. They do this: > > DRIVER-A-COIL-+ > ..| > DRIVER-B--+ > > > And feed the drivers with these waveforms: > > 1.5V..+-+.+-+.+-+.. > ..|.|.|.|.|.|.. > A-+ +-+ +-+ +---... > > 1.5V..+-+.+-+.+-+.. > ..|.|.|.|.|.|.. > B-+ +-+ +-+ +---... > > Where the pulses alternately come from A and B every second. > > If you use a PIC to drive the clock, the driver is easy to program in > software. > > -Chuck Harris > > iov...@inwind.it wrote: >> I understand now why most analog wristwatches do tick every two seconds when >> the battery is low. I believed the logic used this trick to signal low >> battery. >> >> Antonio I8IOV > > ___ > 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] Sidereal timekeeping
An actual quartz analog wristwatch wouldn't do something so mundane as to use a 50uf capacitor to drive the coils. They do this: DRIVER-A-COIL-+ ..| DRIVER-B--+ And feed the drivers with these waveforms: 1.5V..+-+.+-+.+-+.. ..|.|.|.|.|.|.. A-+ +-+ +-+ +---... 1.5V..+-+.+-+.+-+.. ..|.|.|.|.|.|.. B-+ +-+ +-+ +---... Where the pulses alternately come from A and B every second. If you use a PIC to drive the clock, the driver is easy to program in software. -Chuck Harris iov...@inwind.it wrote: I understand now why most analog wristwatches do tick every two seconds when the battery is low. I believed the logic used this trick to signal low battery. Antonio I8IOV ___ 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] Sidereal timekeeping
I understand now why most analog wristwatches do tick every two seconds when the battery is low. I believed the logic used this trick to signal low battery. Antonio I8IOV >Analog quartz clocks may be used as slave clocks. >You do not even have to disconnect the quartz movement. >Just find the coil on the motor and drive it with a square-wave of >0.5 hertz, >in series with a capacitor (about 50mfd) and a resistor (about 200 ohms) >Each type of clock is different, though they all are driven by >something like 1.5 V >20ms alternate polarity pulses. >The actual values are not critical but must be determined for each >type of clock. >If the capacitor resistor combination is wrong it will not work. Too >much signal >will make motors "pole" and refuse to rotate. The capacitor charges >when the >polarity changes and that current operates the clock. The resistor >sets the length >of the pulse together with the capacitor value, as well as setting >the maximum current. >Just swap values until the action is quiet, definite and reliable. >I have used this method on at least 4 different types of quartz >clock, usually from a 5 volt >logic signal. >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. > ___ 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] Sidereal timekeeping
Analog quartz clocks may be used as slave clocks. You do not even have to disconnect the quartz movement. Just find the coil on the motor and drive it with a square-wave of 0.5 hertz, in series with a capacitor (about 50mfd) and a resistor (about 200 ohms) Each type of clock is different, though they all are driven by something like 1.5 V 20ms alternate polarity pulses. The actual values are not critical but must be determined for each type of clock. If the capacitor resistor combination is wrong it will not work. Too much signal will make motors "pole" and refuse to rotate. The capacitor charges when the polarity changes and that current operates the clock. The resistor sets the length of the pulse together with the capacitor value, as well as setting the maximum current. Just swap values until the action is quiet, definite and reliable. I have used this method on at least 4 different types of quartz clock, usually from a 5 volt logic signal. 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] Sidereal timekeeping
That's even simpler! You have to size the capacitor just right, but it's probably not too critical. Thanks Chuck Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Chuck Harris Sender: time-nuts-boun...@febo.com Date: Wed, 18 May 2011 14:09:39 To: Discussion of precise time and frequency measurement Reply-To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Sidereal timekeeping It's been a while since I did it, but as I recall, a simple way of driving the typical motor on a dime store clock is: FF-Q-)|-MOTOR+ .| FF-/Q+ The capacitor charges up during the times when the FF's output is level, and produces a spike of alternating polarity when the FF toggles. You need 1 level transition every second, so the FF has to toggle at a 1/2 HZ rate. -Chuck Harris David Martindale wrote: > The motor is essentially a permanent-magnet stepper motor. The rotor > and stator have just 2 poles each, so the rotor has two stable > positions 180 degrees apart that provide holding torque. Thus, the > motor holds position with no input current for most of each cycle. To > move it, the drive applies a short current pulse to the motor. The > pulses are alternating positive and negative polarity, so you'll need > something like an H-bridge to drive it. Using a 3 volt supply instead > of the 1.5 that the motor was designed for would supply more power > than the motor needs if you keep the drive pulse the same width, but > you should be able to reduce the pulse width until the energy is about > the same as with 1.5 V drive and have the motor still operate. > > Without having actually tried it, I think you should be able to select > a suitable tradeoff between reliable motor operation and power > consumption just by adjusting the "on" time of the drive pulse - no > voltage regulator or voltage dropping resistor needed. > > There's only one stator coil to the motor, and one drive signal, so > you can't control motor direction. The magnetic structures are > apparently deliberately asymmetric to ensure that the motor always > rotates in one direction when it receives a pulse of the appropriate > polarity. (Get the pulse polarity wrong, and the motor just doesn't > rotate). > > Dave ___ 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] Sidereal timekeeping
It would be easy to drive the coil with a push-pull output that can be set to high impedance between pulses and returning the other side of the coil to a high impedance voltage divider across the supply rails with a sizable capacitor between the center. If necessary, a complementary pair/emitter follower can be used to lower the impedance (or reduce the current through the divider) even further. That way, a pulse to ground and a pulse to VDD respectively generate opposite polarity pulses of half the supply voltage across the coil. Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: David Martindale Sender: time-nuts-boun...@febo.com Date: Wed, 18 May 2011 09:42:14 To: Discussion of precise time and frequency measurement Reply-To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Sidereal timekeeping The motor is essentially a permanent-magnet stepper motor. The rotor and stator have just 2 poles each, so the rotor has two stable positions 180 degrees apart that provide holding torque. Thus, the motor holds position with no input current for most of each cycle. To move it, the drive applies a short current pulse to the motor. The pulses are alternating positive and negative polarity, so you'll need something like an H-bridge to drive it. Using a 3 volt supply instead of the 1.5 that the motor was designed for would supply more power than the motor needs if you keep the drive pulse the same width, but you should be able to reduce the pulse width until the energy is about the same as with 1.5 V drive and have the motor still operate. Without having actually tried it, I think you should be able to select a suitable tradeoff between reliable motor operation and power consumption just by adjusting the "on" time of the drive pulse - no voltage regulator or voltage dropping resistor needed. There's only one stator coil to the motor, and one drive signal, so you can't control motor direction. The magnetic structures are apparently deliberately asymmetric to ensure that the motor always rotates in one direction when it receives a pulse of the appropriate polarity. (Get the pulse polarity wrong, and the motor just doesn't rotate). Dave On Wed, May 18, 2011 at 9:20 AM, Bob Camp wrote: > The only obvious issue is to figure out the motor drive side and see what > driving it straight rather than with a switcher does to the motor current. > That's going to involve hacking up a wall clock. Since the clock is likely a > single cell gizmo, the current probably will be a bit high. ___ 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] Sidereal timekeeping
It's been a while since I did it, but as I recall, a simple way of driving the typical motor on a dime store clock is: FF-Q-)|-MOTOR+ .| FF-/Q+ The capacitor charges up during the times when the FF's output is level, and produces a spike of alternating polarity when the FF toggles. You need 1 level transition every second, so the FF has to toggle at a 1/2 HZ rate. -Chuck Harris David Martindale wrote: The motor is essentially a permanent-magnet stepper motor. The rotor and stator have just 2 poles each, so the rotor has two stable positions 180 degrees apart that provide holding torque. Thus, the motor holds position with no input current for most of each cycle. To move it, the drive applies a short current pulse to the motor. The pulses are alternating positive and negative polarity, so you'll need something like an H-bridge to drive it. Using a 3 volt supply instead of the 1.5 that the motor was designed for would supply more power than the motor needs if you keep the drive pulse the same width, but you should be able to reduce the pulse width until the energy is about the same as with 1.5 V drive and have the motor still operate. Without having actually tried it, I think you should be able to select a suitable tradeoff between reliable motor operation and power consumption just by adjusting the "on" time of the drive pulse - no voltage regulator or voltage dropping resistor needed. There's only one stator coil to the motor, and one drive signal, so you can't control motor direction. The magnetic structures are apparently deliberately asymmetric to ensure that the motor always rotates in one direction when it receives a pulse of the appropriate polarity. (Get the pulse polarity wrong, and the motor just doesn't rotate). Dave ___ 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] Sidereal timekeeping
Hi: Here are some photos of the inside of a quartz clock and some related patent links: http://www.prc68.com/I/QuartzClk.shtml Have Fun, Brooke Clarke http://www.PRC68.com David Martindale wrote: The motor is essentially a permanent-magnet stepper motor. The rotor and stator have just 2 poles each, so the rotor has two stable positions 180 degrees apart that provide holding torque. Thus, the motor holds position with no input current for most of each cycle. To move it, the drive applies a short current pulse to the motor. The pulses are alternating positive and negative polarity, so you'll need something like an H-bridge to drive it. Using a 3 volt supply instead of the 1.5 that the motor was designed for would supply more power than the motor needs if you keep the drive pulse the same width, but you should be able to reduce the pulse width until the energy is about the same as with 1.5 V drive and have the motor still operate. Without having actually tried it, I think you should be able to select a suitable tradeoff between reliable motor operation and power consumption just by adjusting the "on" time of the drive pulse - no voltage regulator or voltage dropping resistor needed. There's only one stator coil to the motor, and one drive signal, so you can't control motor direction. The magnetic structures are apparently deliberately asymmetric to ensure that the motor always rotates in one direction when it receives a pulse of the appropriate polarity. (Get the pulse polarity wrong, and the motor just doesn't rotate). Dave On Wed, May 18, 2011 at 9:20 AM, Bob Camp wrote: The only obvious issue is to figure out the motor drive side and see what driving it straight rather than with a switcher does to the motor current. That's going to involve hacking up a wall clock. Since the clock is likely a single cell gizmo, the current probably will be a bit high. ___ 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] Sidereal timekeeping
The motor is essentially a permanent-magnet stepper motor. The rotor and stator have just 2 poles each, so the rotor has two stable positions 180 degrees apart that provide holding torque. Thus, the motor holds position with no input current for most of each cycle. To move it, the drive applies a short current pulse to the motor. The pulses are alternating positive and negative polarity, so you'll need something like an H-bridge to drive it. Using a 3 volt supply instead of the 1.5 that the motor was designed for would supply more power than the motor needs if you keep the drive pulse the same width, but you should be able to reduce the pulse width until the energy is about the same as with 1.5 V drive and have the motor still operate. Without having actually tried it, I think you should be able to select a suitable tradeoff between reliable motor operation and power consumption just by adjusting the "on" time of the drive pulse - no voltage regulator or voltage dropping resistor needed. There's only one stator coil to the motor, and one drive signal, so you can't control motor direction. The magnetic structures are apparently deliberately asymmetric to ensure that the motor always rotates in one direction when it receives a pulse of the appropriate polarity. (Get the pulse polarity wrong, and the motor just doesn't rotate). Dave On Wed, May 18, 2011 at 9:20 AM, Bob Camp wrote: > The only obvious issue is to figure out the motor drive side and see what > driving it straight rather than with a switcher does to the motor current. > That's going to involve hacking up a wall clock. Since the clock is likely a > single cell gizmo, the current probably will be a bit high. ___ 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] Sidereal timekeeping
Hi Ok, say you randomly pick a PIC 16LF1826 as your target device. It typically pulls 7 to 9 ua running with a 32KHz crystal as it's clock and 1.8 to 3.0 V on the supply. Max supply on the low power part is 3.6V so two cells in series is about right for it. An alkaline AA cell is up around 2700 maH according to the ever useful Wikipedia. 10 ua would drain the cell in 11.4 years. The AA's I buy don't last that long sitting on the shelf un-used. The only obvious issue is to figure out the motor drive side and see what driving it straight rather than with a switcher does to the motor current. That's going to involve hacking up a wall clock. Since the clock is likely a single cell gizmo, the current probably will be a bit high. There's always the LCD or LED version to think about Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Wednesday, May 18, 2011 8:09 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Sidereal timekeeping Hi The question can be easily worked out. A PIC running a 32,768 Hz clock will pull X ua doing this or that. I don't know X as I sit here, but it's a number that comes off a data sheet. That much current off of two or three AA cells will let you run for Y days. My guess is that Y is a pretty big number. If it's not, put in C's or even D cells. At some point the number gets big. The drive for the motor is pretty simple, or it was last time I did all this (1970's). Having the PIC drive the motor is not all that hard. The code likely fits in a pretty small part. Weather you use a PIC or something else is open to study. There probably are parts that pull less current running at low speed than the PIC. I can think of a half dozen parts I'd check out. I'd also look for something that's happy with less voltage than most of the PIC's. It would take more time to lay out the pc board than to write the code once you had a target processor and motor in mind. Bob On May 18, 2011, at 12:01 AM, Hal Murray wrote: > > li...@rtty.us said: >> In a full sized wall clock, most of the power is to the motor. On a wrist >> watch - it depends on how well the watch is built. > > Thanks. > > I think that means that it's not silly to generate a PPSS (Pulse per Sidereal > Second) signal by counting to 364/365 of 32678 rather than letting a 15 bit > counter wrap around. > > If "most" means 90% and we use another factor of 10 to implement the > compare/reset, that only drops the battery lifetime by a factor of 2. > > Divide the target count by 2 and toggle one more FF if you need better > symmetry on the output. > > --- > > Hacking the crystal adds another dimension to the hardware/firmware/software > tower. > > Is there a term for that? > > -- > > The party line for something like this is that 1/2 the power goes into the > bottom bit. (assuming we are talking about the logic and not the motor) > > I wonder what the power ratio (battery lifetime ratio) is for custom CMOS vs > say, 4000 CMOS, or C, or HC, or low power CPLD or ??? The CPLD might be > interesting since you don't have to drive external pins/pads. There is > probably some 4000/HC chip that includes a counter but would save power > because it doesn't bring the bottom bit or two out to a pin. > > > > -- > These are my opinions, not necessarily my employer's. 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 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] Sidereal timekeeping
On 5/18/11 2:18 AM, iov...@inwind.it wrote: Michael wrote: You are right, the right value for the crystal would be about 32859.27, but I thought that such a difference could be compensated in the circuitry, that's why I omitted the decimals. before you get into grinding I have a question on your chosen frequency. It doesn't square for me. 1,002737909350795 solar/sidereal time ratio x 32768 crystal frequency 32857,72 required frequency for sidereal clock with 2^15 divider chain I agree with your calculation. Here I ask Jim Lux for help, as when I wrote the first post I simply took that value from his article without re-checking. http://www.techbriefs.com/component/content/article/2299 I think there was an error in that article (most likely a typo somewhere in the transcription process). I'll go check. But your calculation above is correct. ___ 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] Sidereal timekeeping
Hi The question can be easily worked out. A PIC running a 32,768 Hz clock will pull X ua doing this or that. I don't know X as I sit here, but it's a number that comes off a data sheet. That much current off of two or three AA cells will let you run for Y days. My guess is that Y is a pretty big number. If it's not, put in C's or even D cells. At some point the number gets big. The drive for the motor is pretty simple, or it was last time I did all this (1970's). Having the PIC drive the motor is not all that hard. The code likely fits in a pretty small part. Weather you use a PIC or something else is open to study. There probably are parts that pull less current running at low speed than the PIC. I can think of a half dozen parts I'd check out. I'd also look for something that's happy with less voltage than most of the PIC's. It would take more time to lay out the pc board than to write the code once you had a target processor and motor in mind. Bob On May 18, 2011, at 12:01 AM, Hal Murray wrote: > > li...@rtty.us said: >> In a full sized wall clock, most of the power is to the motor. On a wrist >> watch - it depends on how well the watch is built. > > Thanks. > > I think that means that it's not silly to generate a PPSS (Pulse per Sidereal > Second) signal by counting to 364/365 of 32678 rather than letting a 15 bit > counter wrap around. > > If "most" means 90% and we use another factor of 10 to implement the > compare/reset, that only drops the battery lifetime by a factor of 2. > > Divide the target count by 2 and toggle one more FF if you need better > symmetry on the output. > > --- > > Hacking the crystal adds another dimension to the hardware/firmware/software > tower. > > Is there a term for that? > > -- > > The party line for something like this is that 1/2 the power goes into the > bottom bit. (assuming we are talking about the logic and not the motor) > > I wonder what the power ratio (battery lifetime ratio) is for custom CMOS vs > say, 4000 CMOS, or C, or HC, or low power CPLD or ??? The CPLD might be > interesting since you don't have to drive external pins/pads. There is > probably some 4000/HC chip that includes a counter but would save power > because it doesn't bring the bottom bit or two out to a pin. > > > > -- > These are my opinions, not necessarily my employer's. 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 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] Sidereal timekeeping
Michael wrote: >> You are right, the right value for the crystal would be about 32859.27, but I >> thought that such a difference could be compensated in the circuitry, that's >> why I omitted the decimals. >> >before you get into grinding I have a question on your chosen frequency. >It doesn't square for me. > > 1,002737909350795 solar/sidereal time ratio > > x 32768 crystal frequency > >32857,72 required frequency for sidereal clock with 2^15 divider chain I agree with your calculation. Here I ask Jim Lux for help, as when I wrote the first post I simply took that value from his article without re-checking. http://www.techbriefs.com/component/content/article/2299 Do we miss anything, Jim? Antonio I8IOV ___ 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] Sidereal timekeeping
Le 16/05/2011 00:29, iov...@inwind.it a écrit : You are right, the right value for the crystal would be about 32859.27, but I thought that such a difference could be compensated in the circuitry, that's why I omitted the decimals. before you get into grinding I have a question on your chosen frequency. It doesn't square for me. 1,002737909350795 solar/sidereal time ratio x 32768 crystal frequency 32857,72 required frequency for sidereal clock with 2^15 divider chain Regarding the 2^15 division, forget for a moment the second as we know it, and consider a shorter (sidereal) second. Our crystal which makes 32859.27 oscillations in our ordinary second, will make 32768 oscillations in the shorter second. The ratio is saved and we will have the shorter second I'm looking for. Hope I've been clear. Antonio I8IOV Messaggio originale Da: michael.c...@sfr.fr Data: 16/05/2011 0.14 A: "iov...@inwind.it" Ogg: Re: [time-nuts] Sidereal timekeeping Le 15/05/2011 23:39, iov...@inwind.it a écrit : I don't think this will work as the divider chain will give wrong length seconds. Michael, I'm just looking for shorter seconds, in order to keep sidereal time with ordinary clocks. Antonio, Yes I figured that, but I thought the frequency wrong for the 2^15 division. The ration for siderial/solar time according to wiki is 1⁄1.002737909350795, using your value I got 1/1,002777099609375 , which makes your day 86160,723089564, rather than 86,164.090530833. Quite a bit short. My maths may be wrong though. Antonio I8IOV ___ 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] Sidereal timekeeping
li...@rtty.us said: > In a full sized wall clock, most of the power is to the motor. On a wrist > watch - it depends on how well the watch is built. Thanks. I think that means that it's not silly to generate a PPSS (Pulse per Sidereal Second) signal by counting to 364/365 of 32678 rather than letting a 15 bit counter wrap around. If "most" means 90% and we use another factor of 10 to implement the compare/reset, that only drops the battery lifetime by a factor of 2. Divide the target count by 2 and toggle one more FF if you need better symmetry on the output. --- Hacking the crystal adds another dimension to the hardware/firmware/software tower. Is there a term for that? -- The party line for something like this is that 1/2 the power goes into the bottom bit. (assuming we are talking about the logic and not the motor) I wonder what the power ratio (battery lifetime ratio) is for custom CMOS vs say, 4000 CMOS, or C, or HC, or low power CPLD or ??? The CPLD might be interesting since you don't have to drive external pins/pads. There is probably some 4000/HC chip that includes a counter but would save power because it doesn't bring the bottom bit or two out to a pin. -- These are my opinions, not necessarily my employer's. 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.
Re: [time-nuts] Sidereal timekeeping
Hi If the "arms" are to far off from each other the Q starts to drop / resistance starts to climb. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Attila Kinali Sent: Tuesday, May 17, 2011 12:01 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Sidereal timekeeping On Tue, 17 May 2011 11:52:53 -0400 "Bob Camp" wrote: > And you want to keep both sides of the tuning fork equal length to roughly > one part in 50,000 when you move it 1 part in 365. May i ask, why this is important? Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ 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] Sidereal timekeeping
On Tue, 17 May 2011 11:52:53 -0400 "Bob Camp" wrote: > And you want to keep both sides of the tuning fork equal length to roughly > one part in 50,000 when you move it 1 part in 365. May i ask, why this is important? Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ 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] Sidereal timekeeping
Hi And you want to keep both sides of the tuning fork equal length to roughly one part in 50,000 when you move it 1 part in 365. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: Tuesday, May 17, 2011 11:09 AM To: time-nuts@febo.com Subject: Re: [time-nuts] Sidereal timekeeping On 5/17/11 7:01 AM, Jean-Louis Oneto wrote: > I realized that there was lot of way to avoid this [pulldown] problem, > but as I said, it was a long time ago (around 1976...), I was young and > inexperimented, and I just tried once on an almost broken 5 FF (~$1) > wristwatch, then I decided that the software approach would be better > for me. > I used a fine-grained handheld sharpening stone very carefully and just > a few light touchs were enough (um, rather too much!). > a bit of jeweler's rouge embedded on the end of a pencil eraser or wooden stick and a steady hand. 1000 grit lapping paper might be even better, because you wouldn't have to worry about the grit remaining on the quartz. You've got a pretty big move.. one part in 365, right? It's not like moving a 10 MHz crystal up by 1000 Hz. ___ 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] Sidereal timekeeping
On 5/17/11 7:01 AM, Jean-Louis Oneto wrote: I realized that there was lot of way to avoid this [pulldown] problem, but as I said, it was a long time ago (around 1976...), I was young and inexperimented, and I just tried once on an almost broken 5 FF (~$1) wristwatch, then I decided that the software approach would be better for me. I used a fine-grained handheld sharpening stone very carefully and just a few light touchs were enough (um, rather too much!). a bit of jeweler's rouge embedded on the end of a pencil eraser or wooden stick and a steady hand. 1000 grit lapping paper might be even better, because you wouldn't have to worry about the grit remaining on the quartz. You've got a pretty big move.. one part in 365, right? It's not like moving a 10 MHz crystal up by 1000 Hz. ___ 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] Sidereal timekeeping
I realized that there was lot of way to avoid this [pulldown] problem, but as I said, it was a long time ago (around 1976...), I was young and inexperimented, and I just tried once on an almost broken 5 FF (~$1) wristwatch, then I decided that the software approach would be better for me. I used a fine-grained handheld sharpening stone very carefully and just a few light touchs were enough (um, rather too much!). It also depends on what precision you're expecting. I hoped to reach few seconds a day and it was rather tens of second or few minutes. Not so bad, but if I had to reset the sidereal time once a day, it was almost useless for me... At that time, I ended with a small program on an HP-65 (then latter transposed to an HP-41CV), and I soon added a small star catalog including proper motion and precession data for all the targets we were working on at that time (Optical interferometry with aperture synthesis). YMMV... Regards, Jean-Louis - Original Message - From: To: "Discussion of precise time and frequency measurement" Sent: Tuesday, May 17, 2011 1:05 PM Subject: Re: [time-nuts] Sidereal timekeeping Hi Jean-Louis, I'm pleased to hear that you had success trying to modify such a crystal, though you had problems checking the frequency. Regarding this aspect that I'm aware of, my idea is to "hear" to the 32kHz signal with a HP3586A selective voltmeter or a R&S VLF receiver. Further, as electric-guitar players do know, the 1 pps pulse of wristwatches is easily picked up by guitar pickups (many use wristwatches to check pick-ups). These pulses could be compared to pulses coming from, say, a properly set 3325A. And I will use a wall-clock machine which I suppose is stronger than a wristwatch. As there is no issue, to some extent, with the lenght of wires between the crystal and the circuit at these frequencies, I was also speculating about a quasi-continuous monitoring of the trimming process, where for trimming I could use a disc of lapping sheet glued to a Dremel disc. Well, just arrived another suggestion from Bob LaJeunesse too. Regarding software applets (your other post) I have several of them, but as I said my problem is different. Thanks, Antonio I8IOV Hello list, I tried that a long time ago, but the trap I went into was that the capacitance of the 'scope probe was pulling the frequency down, so I ended with a crystal too high in frequency... I'm not sure that you can control the frequency without significantly perturbing it. And waiting to check the rate between each tuning step would take a long time... Regards, Jean-Louis - Original Message - From: "Bruce Griffiths" To: "Discussion of precise time and frequency measurement" Sent: Tuesday, May 17, 2011 1:22 AM Subject: Re: [time-nuts] Sidereal timekeeping Jim Lux wrote: On 5/16/11 2:58 PM, iov...@inwind.it wrote: Neville, at present I have not enough skill with micros to solve the problem. I think I will try modifying a crystal. This would not be that difficult using a lapping sheet or the like. And opening the can would be quite easy using hot air. or a fine jeweler's saw or tubing cutter. As you pointed out, the crystals are cheap, so you can afford to ruin a few while figuring out how to do it. (and then, remember us all, when you're a multi-billionaire having cornered the market on sidereal rate crystals) Since the 32 kHz crystal is likely to be a tuning fork form, one merely needs to shorten the tines to increase the frequency. It may be feasible to do this without removing any of the electrode metallization. Bruce ___ 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. ___ 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] Sidereal timekeeping
Hi Jean-Louis, I'm pleased to hear that you had success trying to modify such a crystal, though you had problems checking the frequency. Regarding this aspect that I'm aware of, my idea is to "hear" to the 32kHz signal with a HP3586A selective voltmeter or a R&S VLF receiver. Further, as electric-guitar players do know, the 1 pps pulse of wristwatches is easily picked up by guitar pickups (many use wristwatches to check pick-ups). These pulses could be compared to pulses coming from, say, a properly set 3325A. And I will use a wall-clock machine which I suppose is stronger than a wristwatch. As there is no issue, to some extent, with the lenght of wires between the crystal and the circuit at these frequencies, I was also speculating about a quasi-continuous monitoring of the trimming process, where for trimming I could use a disc of lapping sheet glued to a Dremel disc. Well, just arrived another suggestion from Bob LaJeunesse too. Regarding software applets (your other post) I have several of them, but as I said my problem is different. Thanks, Antonio I8IOV >Hello list, >I tried that a long time ago, but the trap I went into was that the >capacitance of the 'scope probe was pulling the frequency down, so I ended >with a crystal too high in frequency... >I'm not sure that you can control the frequency without significantly >perturbing it. And waiting to check the rate between each tuning step would >take a long time... >Regards, >Jean-Louis >- Original Message - >From: "Bruce Griffiths" >To: "Discussion of precise time and frequency measurement" > >Sent: Tuesday, May 17, 2011 1:22 AM >Subject: Re: [time-nuts] Sidereal timekeeping > > >> Jim Lux wrote: >>> On 5/16/11 2:58 PM, iov...@inwind.it wrote: >>>> Neville, >>>> at present I have not enough skill with micros to solve the problem. >>>> I think I will try modifying a crystal. This would not be that difficult >>>> using >>>> a lapping sheet or the like. And opening the can would be quite easy >>>> using hot >>>> air. >>> >>> or a fine jeweler's saw or tubing cutter. >>> >>> As you pointed out, the crystals are cheap, so you can afford to ruin a >>> few while figuring out how to do it. >>> >>> (and then, remember us all, when you're a multi-billionaire having >>> cornered the market on sidereal rate crystals) >>> >>> >> Since the 32 kHz crystal is likely to be a tuning fork form, one merely >> needs to shorten the tines to increase the frequency. >> It may be feasible to do this without removing any of the electrode >> metallization. >> >> Bruce >> >> ___ >> 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] Sidereal timekeeping
Hence the advantage of your frequency counter's period averaging mode. Don't measure the crystal, measure the divider it is connected to. That way loading effects are not directly on the crystal. Bob LaJeunesse From: Jean-Louis Oneto To: Discussion of precise time and frequency measurement Sent: Tue, May 17, 2011 8:27:14 AM Subject: Re: [time-nuts] Sidereal timekeeping Hello list, I tried that a long time ago, but the trap I went into was that the capacitance of the 'scope probe was pulling the frequency down, so I ended with a crystal too high in frequency... I'm not sure that you can control the frequency without significantly perturbing it. And waiting to check the rate between each tuning step would take a long time... Regards, Jean-Louis ___ 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] Sidereal timekeeping
Hi again, I forgot to mention this nice piece of software useful to check what you're doing: http://www.gb.nrao.edu/~jbrandt/jLSTclock/ Jean-Louis - Original Message - From: "Jean-Louis Oneto" To: "Discussion of precise time and frequency measurement" Sent: Tuesday, May 17, 2011 12:27 PM Subject: Re: [time-nuts] Sidereal timekeeping Hello list, I tried that a long time ago, but the trap I went into was that the capacitance of the 'scope probe was pulling the frequency down, so I ended with a crystal too high in frequency... I'm not sure that you can control the frequency without significantly perturbing it. And waiting to check the rate between each tuning step would take a long time... Regards, Jean-Louis - Original Message - From: "Bruce Griffiths" To: "Discussion of precise time and frequency measurement" Sent: Tuesday, May 17, 2011 1:22 AM Subject: Re: [time-nuts] Sidereal timekeeping Jim Lux wrote: On 5/16/11 2:58 PM, iov...@inwind.it wrote: Neville, at present I have not enough skill with micros to solve the problem. I think I will try modifying a crystal. This would not be that difficult using a lapping sheet or the like. And opening the can would be quite easy using hot air. or a fine jeweler's saw or tubing cutter. As you pointed out, the crystals are cheap, so you can afford to ruin a few while figuring out how to do it. (and then, remember us all, when you're a multi-billionaire having cornered the market on sidereal rate crystals) Since the 32 kHz crystal is likely to be a tuning fork form, one merely needs to shorten the tines to increase the frequency. It may be feasible to do this without removing any of the electrode metallization. Bruce ___ 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] Sidereal timekeeping
Hello list, I tried that a long time ago, but the trap I went into was that the capacitance of the 'scope probe was pulling the frequency down, so I ended with a crystal too high in frequency... I'm not sure that you can control the frequency without significantly perturbing it. And waiting to check the rate between each tuning step would take a long time... Regards, Jean-Louis - Original Message - From: "Bruce Griffiths" To: "Discussion of precise time and frequency measurement" Sent: Tuesday, May 17, 2011 1:22 AM Subject: Re: [time-nuts] Sidereal timekeeping Jim Lux wrote: On 5/16/11 2:58 PM, iov...@inwind.it wrote: Neville, at present I have not enough skill with micros to solve the problem. I think I will try modifying a crystal. This would not be that difficult using a lapping sheet or the like. And opening the can would be quite easy using hot air. or a fine jeweler's saw or tubing cutter. As you pointed out, the crystals are cheap, so you can afford to ruin a few while figuring out how to do it. (and then, remember us all, when you're a multi-billionaire having cornered the market on sidereal rate crystals) Since the 32 kHz crystal is likely to be a tuning fork form, one merely needs to shorten the tines to increase the frequency. It may be feasible to do this without removing any of the electrode metallization. Bruce ___ 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] Sidereal timekeeping
Neville and Jim and all, there are good pictures of tuning fork crystals at http://en.wikipedia.org/wiki/Crystal_oscillator I think it is the 8x3 mm in size, which is available from China (10 units for 2.5$ including worldwide shipping). Assuming as a reference the diameter of the baseplate, say 2,5 mm without the can, the tines appear to be long in the order of 5 mm. It looks suitable for trimming (see, just below the tuning fork crystal, the picture of a trimmed round crystal). Trimming that way is common practice in crystal manufacturing, and this is what happens when you order a custom crystal (they have blanks which cover ranges). So I'm confident that the Q will not be affected so much. I think it is worth the try. Anyway, Neville, as a backup solution, I would be pleased to consider your design, and I think that others might have an interest too. I would recall that I actually know what sidereal time it is now, by a computer program, but my problem is that I have to rotare a mini torsion balance by means of a low power drawing setup. Cheers, Antonio I8IOV >Hi Antonio, >the 32kHz Xtals are 2mm long tuning forks (that is what I believe >although I have not opened one). >You would have very little chance of modifying it and still have >enough Q left for it to oscillate. >As an alternative you could build an external circuit (a few uA at 3V >supply) and generate a signal to inject into >the existing Xtal osc with the Xtal removed. >The type of circuit that I would build would be a cmos binary divider >connected to a quad gate. >The 4 gate inputs connect to selected binary stages of the divider. >When the gate decodes the >selected number, an extra pulse is added to the count chain. The >output is thus shifted to a higher >frequency. >If you are interested I can try to design the circuit for you, I have >intend to build a Siderial clock >dial for my TBolt. >cheers, Neville Michie > >On 17/05/2011, at 7:58 AM, iov...@inwind.it wrote: > >> Neville, >> at present I have not enough skill with micros to solve the problem. >> I think I will try modifying a crystal. This would not be that >> difficult using >> a lapping sheet or the like. And opening the can would be quite >> easy using hot >> air. This is the fastest way for me, and the device will continue >> to be powered >> by a simple AA cell, which is a non negligible advantage in my >> application. >> All the best, >> Antonio I8IOV >> >>> Antonio, >>> it is quite easy to make an external circuit that uses a 32kHz xtal >>> and divides >>> it down to siderial seconds. It is also easy to drive most analog >>> quartz clock movements from >>> an external circuit. >>> Just what signal do you need? What frequency? and what does it drive? >>> (an alternate polarity >>> quartz clock motor?) >>> It can also be done with a micro if you have the skills. >>> 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] Sidereal timekeeping
Hi In a full sized wall clock, most of the power is to the motor. On a wrist watch - it depends on how well the watch is built. Bob On May 17, 2011, at 12:37 AM, Hal Murray wrote: > >> As an alternative you could build an external circuit (a few uA at 3V >> supply) and generate a signal to inject into the existing Xtal osc with the >> Xtal removed. > > In a typical battery operated clock, what fraction of the power goes to the > oscillator and counter and how much goes to the motor? > > > > -- > These are my opinions, not necessarily my employer's. 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 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] Sidereal timekeeping
> As an alternative you could build an external circuit (a few uA at 3V > supply) and generate a signal to inject into the existing Xtal osc with the > Xtal removed. In a typical battery operated clock, what fraction of the power goes to the oscillator and counter and how much goes to the motor? -- These are my opinions, not necessarily my employer's. 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.
Re: [time-nuts] Sidereal timekeeping
Hi Antonio, the 32kHz Xtals are 2mm long tuning forks (that is what I believe although I have not opened one). You would have very little chance of modifying it and still have enough Q left for it to oscillate. As an alternative you could build an external circuit (a few uA at 3V supply) and generate a signal to inject into the existing Xtal osc with the Xtal removed. The type of circuit that I would build would be a cmos binary divider connected to a quad gate. The 4 gate inputs connect to selected binary stages of the divider. When the gate decodes the selected number, an extra pulse is added to the count chain. The output is thus shifted to a higher frequency. If you are interested I can try to design the circuit for you, I have intend to build a Siderial clock dial for my TBolt. cheers, Neville Michie On 17/05/2011, at 7:58 AM, iov...@inwind.it wrote: Neville, at present I have not enough skill with micros to solve the problem. I think I will try modifying a crystal. This would not be that difficult using a lapping sheet or the like. And opening the can would be quite easy using hot air. This is the fastest way for me, and the device will continue to be powered by a simple AA cell, which is a non negligible advantage in my application. All the best, Antonio I8IOV Antonio, it is quite easy to make an external circuit that uses a 32kHz xtal and divides it down to siderial seconds. It is also easy to drive most analog quartz clock movements from an external circuit. Just what signal do you need? What frequency? and what does it drive? (an alternate polarity quartz clock motor?) It can also be done with a micro if you have the skills. 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. ___ 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] Sidereal timekeeping
Jim Lux wrote: On 5/16/11 2:58 PM, iov...@inwind.it wrote: Neville, at present I have not enough skill with micros to solve the problem. I think I will try modifying a crystal. This would not be that difficult using a lapping sheet or the like. And opening the can would be quite easy using hot air. or a fine jeweler's saw or tubing cutter. As you pointed out, the crystals are cheap, so you can afford to ruin a few while figuring out how to do it. (and then, remember us all, when you're a multi-billionaire having cornered the market on sidereal rate crystals) Since the 32 kHz crystal is likely to be a tuning fork form, one merely needs to shorten the tines to increase the frequency. It may be feasible to do this without removing any of the electrode metallization. Bruce ___ 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] Sidereal timekeeping
On 5/16/11 2:58 PM, iov...@inwind.it wrote: Neville, at present I have not enough skill with micros to solve the problem. I think I will try modifying a crystal. This would not be that difficult using a lapping sheet or the like. And opening the can would be quite easy using hot air. or a fine jeweler's saw or tubing cutter. As you pointed out, the crystals are cheap, so you can afford to ruin a few while figuring out how to do it. (and then, remember us all, when you're a multi-billionaire having cornered the market on sidereal rate crystals) ___ 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] Sidereal timekeeping
Neville, at present I have not enough skill with micros to solve the problem. I think I will try modifying a crystal. This would not be that difficult using a lapping sheet or the like. And opening the can would be quite easy using hot air. This is the fastest way for me, and the device will continue to be powered by a simple AA cell, which is a non negligible advantage in my application. All the best, Antonio I8IOV >Antonio, >it is quite easy to make an external circuit that uses a 32kHz xtal >and divides >it down to siderial seconds. It is also easy to drive most analog >quartz clock movements from >an external circuit. >Just what signal do you need? What frequency? and what does it drive? >(an alternate polarity >quartz clock motor?) >It can also be done with a micro if you have the skills. >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] Sidereal timekeeping
Nope - you're right - most don't go below 1MHz. Got a little loose with my K's and M's I guess. Kinda like - "what's 3dB among friends?" My apologies for the stray lead. Thanks for catching it Jim. Brent On Mon, May 16, 2011 at 10:21 AM, Jim Lux wrote: > On 5/16/11 6:30 AM, brent evers wrote: >> >> Can't you just use a programmable crystal? Digikey will do this for >> you prior to ship. Search on crystal, then under the field type, >> filter by "Programmed by Digikey". Four types pop up as in stock. >> Not sure if they would meet you footprint requirement, but its worth a >> shot. >> > > > Do those go down to 32kHz? We've used them at work in the 40-60 MHz range > (by the way, the noise properties leave something to be desired.. you don't > want to be using them as the reference oscillator for a microwave PLL), but > I don't know if they go low. > > They're also fairly high power (compared to running a clock off a single AA > battery) > > > ___ > 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] Sidereal timekeeping
On 5/16/11 6:30 AM, brent evers wrote: Can't you just use a programmable crystal? Digikey will do this for you prior to ship. Search on crystal, then under the field type, filter by "Programmed by Digikey". Four types pop up as in stock. Not sure if they would meet you footprint requirement, but its worth a shot. Do those go down to 32kHz? We've used them at work in the 40-60 MHz range (by the way, the noise properties leave something to be desired.. you don't want to be using them as the reference oscillator for a microwave PLL), but I don't know if they go low. They're also fairly high power (compared to running a clock off a single AA battery) ___ 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] Sidereal timekeeping
Can't you just use a programmable crystal? Digikey will do this for you prior to ship. Search on crystal, then under the field type, filter by "Programmed by Digikey". Four types pop up as in stock. Not sure if they would meet you footprint requirement, but its worth a shot. Brent On Mon, May 16, 2011 at 8:08 AM, Neville Michie wrote: > Antonio, > it is quite easy to make an external circuit that uses a 32kHz xtal and > divides > it down to siderial seconds. It is also easy to drive most analog quartz > clock movements from > an external circuit. > Just what signal do you need? What frequency? and what does it drive? (an > alternate polarity > quartz clock motor?) > It can also be done with a micro if you have the skills. > cheers, Neville Michie > > > On 16/05/2011, at 8:02 PM, iov...@inwind.it wrote: > >> The background of my request is an OT story. Just to mention briefly, I >> already >> have an ordinary (non-radio-controlled) clock machine which turns a >> miniature >> torsion balance in a sealed glass vessel. It runs on a single AA battery. >> No >> extreme accuracy needed. I wont to modify the rate to sidereal, and might >> have >> to replicate the setup too. I figure that the solution I should pursue is >> getting the "odd" crystals. >> Now it is clear to me that I have to explore two options, a) contacting a >> crystal manufacturer, b) modifying 32768 crystals. >> Thanks, >> Antonio >> >> hmur...@megapathdsl.net wrote: >>> does anybody out there have any ideas as where to find a 32859Hz crystal >> >> (1/ 2 that value would be better) to be used to replace 32768 crystals in ordinary clocks? I think that 32768 crystals cannot be dragged that much. I've already read the JimLux article somewhere on the web, but I would be pleased finding a simpler solution. Also, I already have computer programs that show sidereal time. >>> >>> I think it depends upon what you mean by "ordinary clocks". >>> >>> Most of the recent wall clocks I've seen are battery powered (single AA) >>> and >>> resynchronize nightly via WWVB. >>> >>> If you want sidereal time, you won't have anything to synchronize to. >>> What >>> sort of accuracy are you interested in? If you want reasonable accuracy, >> >> you >>> >>> will need an external signal. (You can provide power over the same >>> cable.) >>> >>> My straw man would be to send 32859Hz down coax or twisted pair and feed >>> it >>> into the xtal-in pin on the clock chip. I'm not sure how to set the >>> time. >>> You can cut the lead to the antenna to make sure it doesn't sync to WWVB. >>> >>> You can make 32859Hz from a PIC (or any micro you like) running off any >> >> handy >>> >>> frequency. Given that this is time-nuts, I'd suggest 10 MHz from a >>> GPSDO. >>> >>> It might be simpler to dump the 32KHz and WWVB chip and drive the motor >>> directly from a 1 PPS signal. Just use a sidereal second rather than a >>> normal second. >> >> >> >> >> ___ >> 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] Sidereal timekeeping
Antonio, it is quite easy to make an external circuit that uses a 32kHz xtal and divides it down to siderial seconds. It is also easy to drive most analog quartz clock movements from an external circuit. Just what signal do you need? What frequency? and what does it drive? (an alternate polarity quartz clock motor?) It can also be done with a micro if you have the skills. cheers, Neville Michie On 16/05/2011, at 8:02 PM, iov...@inwind.it wrote: The background of my request is an OT story. Just to mention briefly, I already have an ordinary (non-radio-controlled) clock machine which turns a miniature torsion balance in a sealed glass vessel. It runs on a single AA battery. No extreme accuracy needed. I wont to modify the rate to sidereal, and might have to replicate the setup too. I figure that the solution I should pursue is getting the "odd" crystals. Now it is clear to me that I have to explore two options, a) contacting a crystal manufacturer, b) modifying 32768 crystals. Thanks, Antonio hmur...@megapathdsl.net wrote: does anybody out there have any ideas as where to find a 32859Hz crystal (1/ 2 that value would be better) to be used to replace 32768 crystals in ordinary clocks? I think that 32768 crystals cannot be dragged that much. I've already read the JimLux article somewhere on the web, but I would be pleased finding a simpler solution. Also, I already have computer programs that show sidereal time. I think it depends upon what you mean by "ordinary clocks". Most of the recent wall clocks I've seen are battery powered (single AA) and resynchronize nightly via WWVB. If you want sidereal time, you won't have anything to synchronize to. What sort of accuracy are you interested in? If you want reasonable accuracy, you will need an external signal. (You can provide power over the same cable.) My straw man would be to send 32859Hz down coax or twisted pair and feed it into the xtal-in pin on the clock chip. I'm not sure how to set the time. You can cut the lead to the antenna to make sure it doesn't sync to WWVB. You can make 32859Hz from a PIC (or any micro you like) running off any handy frequency. Given that this is time-nuts, I'd suggest 10 MHz from a GPSDO. It might be simpler to dump the 32KHz and WWVB chip and drive the motor directly from a 1 PPS signal. Just use a sidereal second rather than a normal second. ___ 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] Sidereal timekeeping
The background of my request is an OT story. Just to mention briefly, I already have an ordinary (non-radio-controlled) clock machine which turns a miniature torsion balance in a sealed glass vessel. It runs on a single AA battery. No extreme accuracy needed. I wont to modify the rate to sidereal, and might have to replicate the setup too. I figure that the solution I should pursue is getting the "odd" crystals. Now it is clear to me that I have to explore two options, a) contacting a crystal manufacturer, b) modifying 32768 crystals. Thanks, Antonio hmur...@megapathdsl.net wrote: > >> does anybody out there have any ideas as where to find a 32859Hz crystal (1/ >> 2 that value would be better) to be used to replace 32768 crystals in >> ordinary clocks? I think that 32768 crystals cannot be dragged that much. >> I've already read the JimLux article somewhere on the web, but I would be >> pleased finding a simpler solution. Also, I already have computer programs >> that show sidereal time. > >I think it depends upon what you mean by "ordinary clocks". > >Most of the recent wall clocks I've seen are battery powered (single AA) and >resynchronize nightly via WWVB. > >If you want sidereal time, you won't have anything to synchronize to. What >sort of accuracy are you interested in? If you want reasonable accuracy, you >will need an external signal. (You can provide power over the same cable.) > >My straw man would be to send 32859Hz down coax or twisted pair and feed it >into the xtal-in pin on the clock chip. I'm not sure how to set the time. >You can cut the lead to the antenna to make sure it doesn't sync to WWVB. > >You can make 32859Hz from a PIC (or any micro you like) running off any handy >frequency. Given that this is time-nuts, I'd suggest 10 MHz from a GPSDO. > >It might be simpler to dump the 32KHz and WWVB chip and drive the motor >directly from a 1 PPS signal. Just use a sidereal second rather than a >normal second. ___ 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] Sidereal timekeeping
On Mon, 16 May 2011 00:01:54 +0200 (CEST) "iov...@inwind.it" wrote: > >Heh.. I cheated and used a 3325B to make whatever frequency we wanted. > >(even better, you can use GPIB to change the frequency vs time to make a > >"clock" that displays unusual things like "height above horizon" or > >"azimuth to orbiter") Whether this would be more useful than just > >driving a dial with a stepper motor is sort of a good question. > > If a 32859 crystal was easily available, that would be a fantastic solution. Such crystals are easily available. It's just that the usual suspects (digikey, farnell,..) do not sell them, as they have not enough volume. Easiest to get them is to call your local sales rep of a crystal manufacturer and ask him what options he has. Usually you can get away with buying a dozen or so of a custom frequency, at the cost of a couple USD each. If you can get one of the "tunable" types, you should be able to get single pieces at a reasonable price. Of course, the stability of those crystals is not time-nuts class, but <100ppm should always be possible and with a bit of tuning, you can get rid of that as well. Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ 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] Sidereal timekeeping
> does anybody out there have any ideas as where to find a 32859Hz crystal (1/ > 2 that value would be better) to be used to replace 32768 crystals in > ordinary clocks? I think that 32768 crystals cannot be dragged that much. > I've already read the JimLux article somewhere on the web, but I would be > pleased finding a simpler solution. Also, I already have computer programs > that show sidereal time. I think it depends upon what you mean by "ordinary clocks". Most of the recent wall clocks I've seen are battery powered (single AA) and resynchronize nightly via WWVB. If you want sidereal time, you won't have anything to synchronize to. What sort of accuracy are you interested in? If you want reasonable accuracy, you will need an external signal. (You can provide power over the same cable.) My straw man would be to send 32859Hz down coax or twisted pair and feed it into the xtal-in pin on the clock chip. I'm not sure how to set the time. You can cut the lead to the antenna to make sure it doesn't sync to WWVB. You can make 32859Hz from a PIC (or any micro you like) running off any handy frequency. Given that this is time-nuts, I'd suggest 10 MHz from a GPSDO. It might be simpler to dump the 32KHz and WWVB chip and drive the motor directly from a 1 PPS signal. Just use a sidereal second rather than a normal second. -- These are my opinions, not necessarily my employer's. 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.
Re: [time-nuts] Sidereal timekeeping
On 05/16/2011 12:01 AM, iov...@inwind.it wrote: I think you're right that you can't drag a 32768 crystal down by one part in 365. Maybe you could do it by opening the can and putting some mass on the crystal resonator? Some mass should be removed, not added. I was considering this possibility. They exist some so called "tuning fork" crystals that might allow for this. And they are very cheap. One could buy a batch of them for a few $ and have a try. What do you think? You only need to carve away sufficiently for being able to pull the rest. If they are cheap you can buy a bunch and afford to go too far on a few attempts. At least it would be a bit unique by todays standards. 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] Sidereal timekeeping
jim...@earthlink.net wrote: >On 5/15/11 2:22 PM, iov...@inwind.it wrote: >> Hi all, >> does anybody out there have any ideas as where to find a 32859Hz crystal (1/2 >> that value would be better) to be used to replace 32768 crystals in ordinary >> clocks? I think that 32768 crystals cannot be dragged that much. I've already >> read the JimLux article somewhere on the web, but I would be pleased finding a >> simpler solution. Also, I already have computer programs that show sidereal >> time. >> Thanks, >> Antonio I8IOV >> > >Heh.. I cheated and used a 3325B to make whatever frequency we wanted. >(even better, you can use GPIB to change the frequency vs time to make a >"clock" that displays unusual things like "height above horizon" or >"azimuth to orbiter") Whether this would be more useful than just >driving a dial with a stepper motor is sort of a good question. If a 32859 crystal was easily available, that would be a fantastic solution. >I think you're right that you can't drag a 32768 crystal down by one >part in 365. Maybe you could do it by opening the can and putting some >mass on the crystal resonator? Some mass should be removed, not added. I was considering this possibility. They exist some so called "tuning fork" crystals that might allow for this. And they are very cheap. One could buy a batch of them for a few $ and have a try. What do you think? Antonio I8IOV ___ 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] Sidereal timekeeping
Hi Antonio: Another way to do it is to use any common crystal (10 MHz would have advantages) and a small PIC micro controller to generate the sidereal * 2^15 frequency. Note this can be done to very high precision. http://www.prc68.com/I/PIC16F88.shtml#PIT Have Fun, Brooke Clarke http://www.PRC68.com iov...@inwind.it wrote: Hi all, does anybody out there have any ideas as where to find a 32859Hz crystal (1/2 that value would be better) to be used to replace 32768 crystals in ordinary clocks? I think that 32768 crystals cannot be dragged that much. I've already read the JimLux article somewhere on the web, but I would be pleased finding a simpler solution. Also, I already have computer programs that show sidereal time. Thanks, Antonio I8IOV ___ 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] Sidereal timekeeping
On 5/15/11 2:22 PM, iov...@inwind.it wrote: Hi all, does anybody out there have any ideas as where to find a 32859Hz crystal (1/2 that value would be better) to be used to replace 32768 crystals in ordinary clocks? I think that 32768 crystals cannot be dragged that much. I've already read the JimLux article somewhere on the web, but I would be pleased finding a simpler solution. Also, I already have computer programs that show sidereal time. Thanks, Antonio I8IOV Heh.. I cheated and used a 3325B to make whatever frequency we wanted. (even better, you can use GPIB to change the frequency vs time to make a "clock" that displays unusual things like "height above horizon" or "azimuth to orbiter") Whether this would be more useful than just driving a dial with a stepper motor is sort of a good question. I think you're right that you can't drag a 32768 crystal down by one part in 365. Maybe you could do it by opening the can and putting some mass on the crystal resonator? ___ 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] Sidereal timekeeping
Le 15/05/2011 23:22, iov...@inwind.it a écrit : Hi all, does anybody out there have any ideas as where to find a 32859Hz crystal (1/2 that value would be better) to be used to replace 32768 crystals in ordinary clocks? I don't think this will work as the divider chain will give wrong length seconds. I think that 32768 crystals cannot be dragged that much. I've already read the JimLux article somewhere on the web, but I would be pleased finding a simpler solution. Also, I already have computer programs that show sidereal time. Thanks, Antonio I8IOV ___ 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.
