Brooke, Here's what I did with a PIC (or Basic Stamp, etc.):
Current limit the coil to two pins of your microcontroller and configure both as inputs (high Z). Then for about 50 ms each second make the pins output; for even seconds set the pins to 0 and 1; odd seconds 1 and 0. /tvb ----- Original Message ----- From: "Brooke Clarke" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Thursday, September 04, 2008 12:25 PM Subject: Re: [time-nuts] How to get 32.768KHz from 10MHz. > Hi John: > > All the quartz clocks I've taken apart have a single coil, for example see: > http://www.prc68.com/I/QuartzClk.shtml > > The drive to that coil is bi-polar and is from a single AA cell, so the > driver > IC must use an H-bridge. If you want to drive a clock like this at 1 PPS > from > a 10 MHz source you will need to use some kind of conversion circuit. That's > why it's easier to generate the 32768 Hz signal and just drive the xtal pins > on > the clock's IC. > > Have Fun, > > Brooke Clarke > http://www.prc68.com/P/Prod.html Products I make and sell > http://www.prc68.com/Alpha.shtml All my web pages listed based on html name > http://www.PRC68.com > http://www.precisionclock.com > http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Web Cam > > Neon John wrote: >> On Mon, 28 Jul 2008 16:35:53 -0700, Jim Lux <[EMAIL PROTECTED]> wrote: >> >> >>>> Seems to me that all the solutions proposed so far are a bit complex, >>>> trying >>>> to go for the 32khz frequency when that's not necessary. The quartz analog >>>> clockworks has a one or two winding stepper motor. The SIMPLEST solution >>>> is >>>> to drive those coils directly with the PIC output and scrap the rest of the >>>> circuitry. >>> Actually, it's not even that complex... it's often an >>> electromagnet/solenoid driving a conventional escapement type clock >>> mechanism. Why use 2 coils when you don't ever need to go backwards? >> >> The clockworks that I've taken apart almost all have 2 coils. One brand has >> one. They all drive a permanent magnet rotor that turns 90 degrees on each >> tick. I'm not sure what the single coil design does to make sure the rotor >> always turns the right direction. Or maybe it doesn't matter if the rotor >> turns a cam and ratchet mechanism. I've never taken one apart far enough to >> know. >> >>> One advantage of generating 32kHz (averaged over 1 second) is that >>> you don't have to build the power driver stage to actuate that >>> electromagnet.. (since it's built into the single dirt-cheap chip in >>> the clock in the first place) >> >> No driver needed. Each coil has about a bazillion (bazillion.000000 for time >> nuts) turns of wire so fine I can't see it without my 7x OptiVisor. I've >> never bothered to measure but the resistance has to be in the hundreds of >> ohms >> or more. It has to be that high to get over a year's operation from an AA >> battery. Duck soup for a PIC output pin driver. >> >> Funny how this works. I've been thinking about this same type problem for a >> few days independent of reading this list. I'm old-fashioned and like analog >> clocks much better than digital. I also like the precision of >> radio-controlled clocks. I've bought several different WWVB analog clocks, >> all of which seem to use the same cheap ChiCom movement. They uniformly suck >> (to use a technical term) at receiving WWVB where I live. The digital >> versions have no problem receiving but I don't like the looks. >> >> What I've been thinking about is a modern version of the Simplex master/slave >> clock system. A GPS disciplined master clock sending out operating pulses to >> slave clocks around my house and shop. >> >> I thought about wireless, including synthesizing my own WWVB signal but I >> know >> that I'll not get enough round tuits to do that. What I'm working toward is >> just about what I described above, except that the master clock will drive 4 >> conductor telephone station wire and the slave clocks will contain no >> electronics. Only the clockwork and the coils. All the clocks will be wired >> in parallel. >> >> This is an open-loop system that assumes all the clocks are in the same >> mechanical position when the master is activated. Perfectly acceptable, >> given >> the relatively few number of clocks and the small area involved. >> >> This architecture should give me what I want - REALLY simple, no electronics >> in the individual clocks, "atomic" accuracy, automatic DST correction and >> perfect synchronism. >> >> Comments? >> >> John >> -- >> John De Armond >> See my website for my current email address >> http://www.neon-john.com >> http://www.johndearmond.com <-- best little blog on the net! >> Tellico Plains, Occupied TN >> No one can be right all of the time, but it helps to be right most of the >> time. -Robert Half >> >> >> _______________________________________________ >> 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.