That's why I suggested killing the BW of the opamps in the partial H bridge configuration previously suggested. Transient response is almost unneeded.
-John ============== > On 08/08/2010, mike cook <[email protected]> wrote: >> Check out Bryan Mumfords page. >> http://www.bmumford.com/clocks/em2/index.html > > I did not want to kick the pendulum with a pulse each swing as the > drive would be part and parcel of the existing clock mechanism. What I > was interested in was Don Mimlitch's description of how the Riefler > Pendulum and Warren Telechron Master Clocks work. The control of > constant current to the electromagnet under the pendulum seems quite > similar to an EFC and could perhaps be used in a PLL to sync with a > reference source, as Jim was originally proposing. > > Of course, retrofitting a conventional clock like this would require > the attachment of a magnet to the pendulum, necessitating reducing the > weight of the pendulum to account for it, installing an electromagnet > under the pendulum and arranging for each swing of the pendulum to > produce some form of pulse signal. Of course, the timing in pulses per > second of the original clock would have to be determined and the > frequency standard divided down to match this rate before both signals > are fed to a comparator and LPF to provide the 'EFC' voltage to > control the electromagnetic current. > > Steve > >> Le 08/08/2010 11:14, Steve Rooke a écrit : >>> I was rather more thinking of the setup that Don was suggesting as not >>> many domestic clocks have a seconds pendulum and it would otherwise >>> take dividing down a referenced oscillator to the correct frequency. >>> >>> Cheers, >>> Steve >>> >>> On 08/08/2010, Neville Michie<[email protected]> wrote: >>> >>>> Not many clocks are set up with the gear to modulate the rate, >>>> but they are all still sensitive to injection locking. >>>> A tiny rare earth magnet on the pendulum (say 1/2 way down the >>>> pendulum rod) >>>> and a coil fed with a stretched (say 250ms long) PPS or for a seconds >>>> pendulum >>>> PP2S pulse will pull the pendulum into phaselock with a surprisingly >>>> small amount of power. >>>> In fact if you turn off the drive it would keep the pendulum swinging. >>>> Cheers, Neville Michie >>>> >>>> On 08/08/2010, at 6:00 PM, Steve Rooke wrote: >>>> >>>> >>>>> This is very interesting and I wonder if the capabilities of this >>>>> system being applied to any clock pendulum. If this sort of control >>>>> any pendulum, then I wonder if it's possible to sync it to some >>>>> standard. >>>>> >>>>> Steve >>>>> >>>>> On 08/08/2010, Don Mimlitch<[email protected]> wrote: >>>>> >>>>>> Jim Said: >>>>>> >>>>>>> It also has a coil mounted near the pendulum and a fixed magnet >>>>>>> on the >>>>>>> pendulum bar and this coil connects to a box down below with a >>>>>>> meter >>>>>>> and a knob. They are labeled in sec/day. The electronics in the box >>>>>>> are not clear (being quite old) but by measuring the current in the >>>>>>> coil it quite simply increases the current one way to slow the >>>>>>> clock >>>>>>> and the other way to speed it up. (I'll admit the physics of this >>>>>>> doesn't make sense to me - but it works!) >>>>>>> >>>>>> I have a Warren Telechron Master Clock used in Power Stations in >>>>>> the 20's to >>>>>> regulate the 60 Cycle so that household clocks using synchronous >>>>>> motors >>>>>> would be accurate to seconds a day. >>>>>> >>>>>> This clock has a similar permanent magnet at the end of the >>>>>> Pendulum and >>>>>> a battery connected to a potentiometer to adjust the current flow >>>>>> positive >>>>>> or negative in an electro-magnet below the pendulum.. >>>>>> If the bottom of the magnet in the pendulum is "north" and the >>>>>> current in >>>>>> the electromagnet is flowing such that its top face is North, then >>>>>> this will >>>>>> repel the pendulum causing its swing to be wider and contrary to >>>>>> common >>>>>> knowledge the swing of a fixed length pendulum is not constant >>>>>> regardless of >>>>>> the swing. (Huygens discovered this in 1670 an found by forcing >>>>>> the arc of >>>>>> the swing to be cycloid instead of circular he could produce uniform >>>>>> oscillation) Thus if the arc is longer the swing takes more time >>>>>> and the >>>>>> clock runs slower. >>>>>> If the current flows in the opposite direction and the two magnets >>>>>> attract >>>>>> then the arc is shortened and the clock runs faster. Of course my >>>>>> master >>>>>> clock isn't as accurate as a Riefler pendulum clock. Also the >>>>>> magnet in my >>>>>> clock has lost it's magnetism over time and I can't use this >>>>>> regulation. >>>>>> >>>>>> So the goal of your adaptation is to have precision control of the >>>>>> current >>>>>> flow in the positive or negative direction. Others on the list are >>>>>> better >>>>>> then me at describing how you might achieve this. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> time-nuts mailing list -- [email protected] >>>>>> To unsubscribe, go to >>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>>> and follow the instructions there. >>>>>> >>>>>> >>>>> >>>>> -- >>>>> Steve Rooke - ZL3TUV& G8KVD >>>>> The only reason for time is so that everything doesn't happen at >>>>> once. >>>>> - Einstein >>>>> >>>>> _______________________________________________ >>>>> time-nuts mailing list -- [email protected] >>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ >>>>> time-nuts >>>>> and follow the instructions there. >>>>> >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- [email protected] >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>>> >>>> >>> >>> >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > > -- > Steve Rooke - ZL3TUV & G8KVD > The only reason for time is so that everything doesn't happen at once. > - Einstein > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
