Re: [time-nuts] Am I the only Time Nut who doesn't wear a watch?
On 7/10/2011 4:10 PM, Hal Murray wrote: omni...@gmail.com said: Then there is this little number... http://forums.watchnet.com/index.php?t=treegoto=415170rid=0 From their web page: The power reserve is 52 hours, and the watch is actually very accurate at about plus or minus 4 seconds a day. 4 seconds per day? I'd expected better from a very expensive watch. Are belts nasty when it comes to keeping good time? I wear a $50 watch that is a radio controlled atomic watch. Less than 1/2 a second off at any time, it's plenty good enough for normal human affairs. It's the only watch (so far) that I found to be satisfyingly accurate. I use it as my ship's chronometer when I drive and potentially have to use one of Chicago's parking pay boxes or to deliberately time my arrival into a free parking spot that depends on timing to get. (i.e. the school zone parking tactic) 4 seconds off a day? If it's a Rolex, I'd (understandably) be PISSED!!! I'd expect a watch that damn expensive to be off less than the 5 milliseconds to grab the WWVB signal! After all, isn't the whole purpose of a watch is to keep time? Unless, I suppose, you really want the bling factor... (and I'm not into bling) ___ 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] Am I the only Time Nut who doesn't wear a watch?
On 7/10/2011 6:33 AM, Raj wrote: To me when someone tells me a time of day the first thing I visualize is the clock hands and not numbers. I suspect the present gen visualize numbers. They must have trouble with 60 minutes in the hour.. a quarter past six and such.. I'm 48 years old and prefer digital. Why? Analog clocks are such that a little play is found with the minute hand. That means that if you calibrate it to be accurate (within the limitation of the movement) on one side of the hour it will lose or gain a minute on the other side due to the play in that needle on the gauge. Digital completely eliminates the play found with the minute needle. Note that the play comes into, well, play, if the clock is mounted vertically on a wall and is a decent large size. An analog watch will not have the problem nor will a clock with 3 separate stepper engines for each of the 3 needed gauge needles. (or at least 2 steppers and gears for the hour needle with direct drive for the second and minute needles) The typical wall clock will have one stepper engine and and gears for the minute and hour needles on the gauge with direct drive for the seconds needle. Therein lies a source of the play with the minutes needle. What's a measly minute off? Well, we all know! :) If you want a watch with some bling to it, try a Citizen Skyhawk series analog watch. These gems are radio controlled so it'll be less than half a second off at any time and are a little blingy (and a little expensive like $300). ___ 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] Am I the only Time Nut who doesn't wear a watch?
On 7/10/2011 5:04 AM, Javier Herrero wrote: My car has an interior look similar to this: http://upload.wikimedia.org/wikipedia/commons/thumb/c/c7/Jaguar_XKR_Convertible_interior.jpg/800px-Jaguar_XKR_Convertible_interior.jpg Time ago, I pick a young engineer (quite digitally oriented, may I say) to go somewhere. He saw the three gauges in the central console (oil pressure, analog clock, and battery), pointed to the center one (the clock) and asked me: and what does this one measures? I was quite surprised by the question... :) Put that bloke in the engineroom of a ship and he'd be COMPLETELY lost looking at the dash. :) ___ 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] Am I the only Time Nut who doesn't wear a watch?
On 7/9/2011 10:18 PM, Raj wrote: I dont wear a watch since 25 years or more. Plenty of clocks around and now will cell phone and other personal devices all have clocks. Watch it. Those clocks on the cell phones are consistently slow compared to a WWVB watch. The time clocks where I work which have a phone connection to an (real deal) atomic clock are one second slow compared to my WWVB watch. At the end of the day I supply a countdown taking into account the one second off. The second off is due to digital delay in the system. It's about like having my own time clock except I can't punch in or out with the watch. Can't have EVERYTHING! But you are right about the plentiful number of clocks around, most being less than a minute off, usually slow. For years I didn't wear a watch until I got a WWVB watch. I was never happy with watches until I got that one due to inaccuracy. I want my watch to be exact. (OK, less than half a second off) ___ 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] Atomic clock on a chip
On 5/11/2011 9:24 PM, James Fournier wrote: http://www.smartertechnology.com/c/a/Technology-For-Change/Smarter-Atomic-Clock-on-a-Chip-Debuts/ NIST (aka bureau of standards) invented an atomic clock movement that is the size of a grain of rice. That's almost good enough to fit in a self-setting wristwatch, if they can get the power needs down enough. A radio-controlled REAL atomic watch would be awesome, as it'll never be more than a few milliseconds off at any instant. The watch could even be designed so that the user sets in the city and it compensates for time of radio propagation. (like about 5 milliseconds from the WWVB transmitter to Chicago) An atomic watch is as of now is no more than a half a second off at any time, good enough for human affairs. (but not for a good time nut!) ___ 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] 50/60 Hz clocks
Cezary Rozluski wrote: Well – it is nice solution presented, but I would like ask you what would be from time-nuts perspective simple (the simplest ?) solution to drive such 50/60 Hz clocks without to much overweighed stuff (and of course without modifying the clock itself addig e.g step motor etc, etc) We had this discussion a while back. Try the archives and search on Got 60HZ?. I started that discussion with having come up with a dithering strategy to make a nearly exact 60HZ squarewave out of 10,000HZ from a frequency dividing chip. From 10,000HZ, making 50HZ would be easy if you don't mind a squarewave. You rig an Arduino to the frequency dividing chip and program to taste. The hardest part is to make the 1/2 volt 10MHZ sinewave into the 10MHZ TTL-compliant squarewave! ___ 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] 50/60 Hz clocks
Robert LaJeunesse wrote: Poor man's solution: Use an Arduino to read the Thunderbolt 1PPS and lock a 50Hz (or 60Hz) square wave to the 1PPS. Any resulting jitter can likely be kept in the tens of microsecond range, easily filtered out by the clock mechanics. Filter the square wave a bit and feed it into an audio amplifier (or two) of sufficient power to run the clock. (Possibly a 12V powered bridge amplifier at ~14W would be adequate?) Use some sort of audio output or filament transformer backwards to create the proper line voltage to run the clock. Maybe run the whole thing off a 12V battery with float charger for uninterruptible timing. When using the power transformer backwards keep in mind the impedance output of the amplifier. Audio amplifiers are rated in watts into an 8 ohm (or 4 ohm) load. So, what you want is a power transformer of desired wattage and the low voltage side having a volt and amps rating that would match an 8 ohm load or 4 ohm load. Then, you hook it backwards (i.e. as a step-up transformer) to an audio amp of a rating higher than the transformer then hook the signal to the input and use the volume knob as a throttle. Turn up until desired voltage is reached. Have fun! ___ 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] Happy New Year from Melbourne UTC+10
swingbyte wrote: First New Year at home ( 20 week old baby ) fortunately the neighbours have let off a few fireworks. Happy New Decade, mate! (and thanks for that quirk in Strine, too!) In America, we don't let off fireworks, but instead set them off or light them off. (possibly Chicago-specific for the latter) In the USA Navy, they light off boilers, creating a Navy-specific term. If you want fireworks on a New Year's, try Napoli Italia. The Italiani go nuts on a New Year's with them, and also throw old items over the side from their apartments too. Walking the streets with firecrackers can get dangerous! I was there for the Dec 31 1989 New Year's. ___ 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] Loran?
Thomas A Frank wrote: I await the day when someone opines as to the number of angels that can dance on the head of a GPS antenna. Oh dear, now I have this vision in my head of a bunch of angels impaled upon the antennas of a GPS satellite, much like how some of the folks who get involved in the Running of the Bulls end up. Sounds like the question of how many parking meter fairies can dance atop a Chicago parking pay box (with uncalibrated clock). HINT: This is why I have a WWVB watch and avoid metered parking spaces! ___ 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] Us Time Nuts and... Wrist Watches.
Cook Mike wrote: Le 24/12/2010 18:00, Michael Poulos a écrit : We all enjoy good accurate time keeping. :) What is your favorite watch? My watch (so far) is a Casio WaveCeptor digital watch that gets the WWVB signal and calibrates itself Not sure I have a favorite. I can't find any that do what exactly what I want, but I did go somewhat gaga the other day and got a Citizen Chronomaster (calibre A660). Spec'd to +- 5 secs a year without recourse to GPS/radio references. I always have three or four running at any one time in a desk drawer. And a few , well quite a lot really, in reserve. I guess it depends on the situation you inject yourself into. Except for the two limitations I love that watch. In the case of ANY watch I will want WWVB accuracy like my present watch. Where I work the time clocks are with hundreths and self-calibrate with an atomic clock in Kentucky. I provide a countdown like NASA at the end of a workday. 5.4.3.2.1.Liftoff aka Double-O! Time to go! ___ 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] Got 60HZ?
Javier Herrero wrote: It seems that we're all trying to find the most obstuse way to obtain 60Hz from 10MHz since the division is not integer... why not simply multiply the 10MHz input signal by 3 and feed the resulting 30MHz signal to any suitable divider by 50 chain? the result will be nice, spectrally pure and even 50.000% duty cycle :). To multiply the frequency means weird RF circuitry to start off. If you start off with the 10 million HZ and divide, you only get better as any phase jitter gets lost in the division. As you divide far enough, the phase jitter gets to those leap pulse jitters. To design around the problem of Rb (my bad about Rb versus Ru) movements you have to have a second one ready to start once the original goes bad. This will occur with a cesium movement, like a good Agilent 5071A cesium movement every bit as well A fun question is why Rb movements are so common but Cs movements are rare and expensive. ___ 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] Got 60HZ?
paul swed wrote: WHAT chip are you using that has the nice divide by 10 outputs please? I have been wiring 74ls XXXs for years what a pain. Tired of the soldering. Thanks Paul The chip was one I got on eBay from a different seller than the Ru movement. The chip number is a C8051T602.It's actually a tiny printed circuit card in a DIP chip pinout format. I have no idea how many or few of these bad boys are to be found anywhere. Anyone know of a microcontroller that'll take the raw sinewave from a Ru movement? THAT would be nice! BTW, a really cool frequency to make would be the 32768HZ of a normal quartz movement. Take a radio controlled wall clock and rubidiumize it and let it self-reset. in between self-resettings it'll remain astoundingly accurate, great for lousy reception areas. ___ 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] Got 60HZ?
Chris Albertson wrote: What you are doing is dithering. That is the Leap Count. There is a better way that gives you the exact solution. If you think about it, what is the computer doing between counts? nothing really. Put that time to use. Why not measure the the 1Khz period. Or measure the period of the last 1000 counts. then toggle the output at 60/1000 of that period. This is a software phase lock loop . Another way to think about this is to think what would you do if your frqency reference was a one pulse per second tick. I got the dithering idea from an obvious source: the calendar. Not knowing about dithering but knowing everyone on the list knows about leap time intervals, the term I used is a no-brainer. With a 1HZ output, the thing I would do is feed it into an Arduino for the display. If I wanted a display with .1 of a sec display added, I'd have let's say the ramp-up to HIGH trigger the Arduino and code in time-waste code as needed to get the flipping intervals - including any leap wasted CPU cycles. Like any frequency multiply scheme you need a really accurate reference source... like a Ru movement. ___ 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] Got 60HZ?
Recently I bought a Efratom Ru frequency standard from eBay and a frequency divider chip that makes 1MHZ,100KHZ,25KHZ,10KHZ,100HZ and a 1HZ output. Today I thought of a way to make a nice 60HZ so you can use a mains-powered clock for the display (using amplifier and transformer wired backwards). But, now you'll need 60HZ. A European has it easy with 50HZ as you use a BASIC Stamp or Arduino to divide the 100HZ output. But for 60HZ I came up with a solution: You set up the Arduino to take the 10KHZ from the divider chip and program it to count off 83 pulses to flip an output. But wait! Unless you add a leap count every 3 flips of the output, it'll run fast. Assume at the start the Arduino output starts high then turns low: (83+83+84+83+83+84)*20 = 10,000 pulses = one second H__L__H__L__H__L Every output cycle and a half the voltage swing is a little over 1 percent longer because of the leap count. This means that the distortion adds a slight inaccuracy, not enough to upset New Year's revelers. But if you want a better 60HZ, try using the 100KHZ: (833+833+834+833+833+834)*20 = one second You see where this is going with leap counts. The ultimate of course is one really good Arduino and (after a hex inverter to amplify it) take the straight 10MHZ and apply this leap count technique: (8+8+83334+8+8+83334)*20 = one really accurately made 60HZ = one nice second, just the thing for a Nixie clock. :) Now, what is a good hex inverter to take the 10 million HZ of my rubidiom movement to feed a frequency divider chip (and later Arduino)? It needs to take the .5 of a volt sinewave and squarewave it and in a normal 14 pin DIP (breadboardable) package. ___ 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] Determining Time-Nut infection severity.
Richard H McCorkle wrote: Time-Nuts, New members to the Time-Nuts list may wonder if the Time-Nut disease has infected them just by joining the list. A clear indication that someone has been infected with the Time-Nut disease is they own a reference that provides accurate time to better than 1us and frequency to better than 1e-9. This is a mild form of the disease, but as the infection progresses multiple standards appear, each having greater accuracy than the last... P.S. This was written for enjoyment and should not be taken seriously as an indication of a true medical condition. I guess I'm a mild case. I bought a rubidium standard/clock movement and I'm slowly building my own atomic clock. I have a WWVB wall clock and a WWVB wristwatch. I first got the time bug discussing the Chicago parking meter deal on a Chicago-specific blog. I bought the watch to use as my car's chronometer for parking purposes. I was always vulnerable to the time bug since childhood and New Year's Eve. I got my Efratom Rb movement and a frequency divider chip on eBay, of course. If I were to hit the Lottery, I'd love to get one of those Agilent 5071A Cs movements! ___ 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.
