Self Winding Master Clocks in Central Offices
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- Опубликовано: 1 июл 2024
- This video discusses the use of synchronized self winding clock systems in telephone central offices.
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As a casual Horologist (timekeeping fan) I've always wondered how they managed time synchronization between the Naval Observatory and the rest of the nation. Now that I find out, I'm very impressed.
i swear i could listen to Sarah describing anything.
Hard same
@@bilbobrasky1804 If Sarah feels fine, it's ok !
Sarah is a legend (or she is in my heart at least)
@@bilbobrasky1804 if you feel that way, that's fine.. but saying so, it's not helping anyone or anything, and is in fact only spreading pain/negativity for no reason other than you feeling superior from bullying, and amused for a brief moment by offending people, because you got an ick from something you don't understand.
Like for example, I could say: "most conservatives, homophobes, transphobes, most Christians and gun loving rednecks will never be half decent human beings and should stop breathing to save air for the rest of us"... but I keep it to myself because that's mean and unproductive! Instead I'll be kind and have actual, civil discussion about the things that give me an ick 😉 or say nothing.
Tl;dr if you have nothing nice to say.. stfu 🙃
Back in the 70s, my High School had some type of master clock system. One day I had the brilliant idea to short the two wires feeding a classroom clock. Well, all the clocks in that portion of the school stopped at 12:21 pm for almost the entire rest of the school year until they fixed whatever breaker I tripped. They chalked it up to a "New Construction Malfunction."
It's just delicious that you have the 1930s clock synchronized to NTP. I love it.
I think it's great that the synchronization involved ultimately uses the same source for time services. The US Naval Observatory Clock (at least in the USA) is the standard time source, regardless of whether the synchronization path is through Western Union, or NTP. Some things are arguably right.
I'll grant that many time servers that NTP uses are synchronized via GPS these days, but those time sources either get corrected, or have correction information available to compensate for the fact that atomic clock sources on GPS satellites do not adjust for leap seconds, and because they are in orbit, operate at a different time speed than the naval observatory clock. Likewise if you use NTP in a country that specifies that people in that country use a clock reference that country maintains, it would not be the same. That may require using an NTP pool as specified there. Not my bally-wick.
Thank you for the interesting article. I’ve had two experiences with similar clocks.
When I was in public school, the big clock in the principals office and the clocks that were synchronized we’re pretty common in most of the schools I attended. However, by the 1960s the slave clocks started having trouble sometimes being as much as 10 minutes off when the synchronizing pulse came in and they didn’t fare so well because the clocks weren’t supposed to be that much off. Eventually in my school they just covered the clocks up and we didn’t use them anymore. However, the master clock still rang the bells.
The other self-winding clock I ran into was in my 49 Chrysler sedan. This had a clock in it and when it malfunctioned I was surprised to find out that it had a motor in it to wind the spring, much like the mechanism you described. That was the first time I realized that not all clocks were powered the way I thought they were.
I have one more related thing. When I was in Hawaii, the military communication system also ran on 24 V and we had 12 cells that were in glass containers in our back room to provide the power. Again, the power was provided by the cells which were charged by the electrical system, but this approach assured that if we lost electrical power a communication system would continue to work.
Thanks again for the great presentation.
This is awesome! As a software engineer I have always loved studying the history of telephones and clocks as both are precursors to modern computers. This video combines the two of them!
(Clocks were mechanical computers for tracking time, and telegraph and telephone systems pioneered the electrical and information science that became computer science and engineering. All of these led directly to what we take for granted today, super computers on our desks and in our pockets.)
Welcome back Sarah, we missed you.
I love this. I'm a broadcast engineer and one of my mentors had restored one of these in the early 2000's. I remember being absolutely fascinated with the back story. I'm both a telephone history and broadcast history nut and these clocks are heavily a part of broadcast history as well. If you look at old radio photos, you'll often see a Western Union clock in the background. They were a essential part of any broadcast workplace for a long period of time.
Before working in the old Bell System for a quarter century, I was in broadcasting, and the radio station I spent most time at had one of the classic WU clocks with the little red lamp that would light and the hands would twitch with the synch pulse.
I've been researching the IBM Studio Clock System, which I assume was designed to compete with the Western Union system. The IBM system used a master clock that synchronized to WWV/WWVH every hour and coordinated with the studio clocks every minute. They were available in the mid-1950's. There is virtually no information about the IBM system on the web but NIST has one of the master clocks on display at a lab in Boulder, CO. These IBM systems were not commercially successful so I've often wondered how studios kept accurate time without them.
I recall touring the "new" WGY (radio)/WRGB (television) studios on Balltown Road in Niskayuna during an open house after they moved from downtown Schenectady. They had some system of clocks which synchronized 30 seconds into every minute. I don't know who made the system.
As for IBM, they did have a division which provided master clock systems. I have not found information on the internet about the specific system that my high school used.
I was told that the Self Winding Clock Company became IBM does anyone know if this is true?
Amazing how different Master/slave clock systems are over here in the UK. Whilst IBM/ITC systems are not unknown, most were Synchronome or Gents' systems using seconds pendulums. The Post Office used their own systems in telephone exchanges.
You're keeping the analog history of human communication alive! Thanks, and great to see you posting! I'll check out your recommended video regarding clocks as well. Peace!
As somebody who spends their days working with Telecommunications technology, i LOVE your content. I'd love to visit the museum sometime! Thanks for sharing this, and I look forward to future content.
Thank you so much for Mentoring the museums collection. Great job of explaining the Western Union master clock system. Your explanation was clear and concise I loved your ESS series though I confess that I had to watch it multiple times to get the big picture.
It’s absolutely fantastic that there are people like yourself that know these things in detail and can explain all these great things from the past so we can appreciate all the hard work and thinking that went into them. Thank You very much for the post!
Love it!
I am an amateur horologist as well as an electronic tech, and WWV and timekeeping was always part of the radio history I learned and enjoyed growing up.
These clocks were everywhere where accurate time was needed for science and industry, but the biggest use was for ships at sea, for navigation. Which made me desire to get into the military, and radio electronics, but that fell through, due to health issues.
But I always had a soft spot for the telephone industry, as they were THE communication experts in my early youth.
I envy your hobby, and setup! Keep it up!
Wow! Awesome video. Thank you. It brought back memories of the clocks and synchronization system my High School would use. They sent a audio tone superimposed onto the 120vac at specific intervals - I think like 1 or 2 minutes before the top of the hour. That signal that they put over the building's power distribution was soo strong that it would make the computer monitors on some computers go nuts for a few seconds, and I was even able to faintly hear it from my home over a mile away coming out of transformers and any amplifier that was picking up AC hum.
I bet the power company just loved that.
My schools since 2010 or so used rectangular atomic clocks
Keep up the awesome work, Sarah! I love everything you and everyone else at the museum do!
Yay! So excited y’all are still making videos 😎 was just in Seattle about a month ago but SADLY couldn’t make it to the museum. Gonna try and come by next year FOR SURE!
Glad to see you posting again! Looking forward to the upcoming videos :)
Thank you for another great video! That was a bunch of great information on something that most people would just walk past and give nary a mind to. Very well done, looking forward to the next video! Cheers!
Very informative! I actually have a IBM sub-master clock that contains several relays and a programming unit. It also runs off of 24vdc. A central time service would send a pulse to it the same way stopping it at the hour to sync. It's one of the larger ones with the heavy dual jar pendulums. Thinking of running a few secondary clocks off of it some day. Keep up the good work!
I love this stuff. Thanks for keeping this channel going with great videos.
Self-winding clocks are the best! Thanks for this great video.
How I wish I'd found this channel a year ago. Marvellous to have such detailed explanations and pics. I did giggle a lot when you described missing that top of the hour event!
Super excited for the new videos again!!
Awesome work. I love these clocks very similar to the ones we had in switch rooms in the UK.
I am officially geeked out. Marvelous video!!!
You answer questions that I didn't know that I had. I worked for Pacific Bell for 15 years
Hi Sarah I really enjoyed the video, I learn so much while I watch your channel. I appreciate all that you have done! hope you had a nice summer
One of the interesting things I observed in my high school classrooms where we didn't have a battery backup for the office master-clock systems was when they reset the time on the master clock, the hands on the classroom clocks would all move in response. In many cases the classroom clocks were little more than a gear train for hour and minute, being driven by a stepper motor that was operated by that clock pulse. As the clocks were only showing hour and minute, it was very possible that they were only getting pulses to move forward every 6 or 10 seconds, because most people wouldn't notice a change in time beyond that. Usually this was the result of a power outage, the other time these clocks might shift unexpectedly was the Monday morning after the start or end of DST.
Very rarely a clock would loose sync with the master clock, and fixing that would involve someone (senior custodian?) would step in and use the thumb wheel on the bottom of the clock to adjust the clock to the correct time. As these clocks themselves did not need local power, they didn't have batteries.
It would not surprise me if schools today either didn't have classroom clocks, or if those clocks all were the variety operating off of a single AA battery. While it might be easy to take one of the old slave clocks, put in an esp32 and a stepper driver to handle driving the clock. I suspect getting the display of such an analog setup synchronized, would probably involve some custodian with a cell phone or tablet to come in, link to the esp32, adjust the clock hands through the esp32 to point to 12 noon, then have the esp32 move the hands from there to the current time, and carry on. I would think this would be a reasonable solution for nearly every analog 'radio' clock. Move the lever on the back of the clock to the correct time zone, set the hands to 12 noon, press a button to 'sync' the display, and the microcontroler in the clock deals with moving the hands around to the correct current time.
And usually the first indication that classroom clocks were going to be 'corrected' was about 3rd period the end of class or start of class bell would go off in the middle of class, and everyone would look up and see that the wall clock was off by 3 and a half hours. Then wait for the clock adjustment to kick in, and listen to the start and end of class bells to go off for first and second periods, and so on. Bit of a distraction from learning that day's chemistry curriculum.
I worked in radio in the early ‘70s and we had the self-syncing Western Union clocks. They would receive a signal over a telephone circuit at the top of the hour and the minute and sweep second hand would snap to the 12 o’clock position. A precise time source is critical when you need to do smooth network joins.
A very excellent and educational presentation.
this was really great. I always wondered how those clocks worked. Glad I found your channel.
Thank you, I have always liked synchronized mechanical clocks. This is one of those systems I have slept on being a digital individual.
Sarah, if I haven't said it recently --- you rock... so... hard. I love the clock, what a thing!
Happy New Years! So stoked I stumbled onto your channel a few weeks ago 🤓🥳
Thanks for this wonderfull explaination of the beautiful old semi-master clock.
Glad you enjoyed it!
Wow Sarah, what a beautiful brain . . . fantastic video !!! Huge time fan here, on the periphery of time discussions in the early days of GPS, various secure radio applications, later cellular phone service, and my wife's employment with the Voice of America with their synchronized clocks, that inspired me to install synchronized (now, power over ethernet, and time synch from a GPS antenna installed on the roof) in a couple of offices where I worked. So glad Google decided you belong in my "space". Have a couple of grandfather clocks here (only one running) with modern Hermle movements, and since the 2003 hurricane Isabel knocked out our power for a week, and I discovered that most of the clocks in my house were not actually clocks, but frequency counters, and running on generator power - which frequency control was gross - and seeing my "clocks" lose all sense of time, I spent several years obtaining clocks tied to WWV in almost every room - generally change the batteries once a year - generally after the "fall back" [run forward 23 hours] DST-->ST setting. Now we just need 999,992 more subscribers to this channel.
Hi Sarah, you run a fascinating channel. Synchronised clocks were part of my job 35 plus years ago. The slaves were deliberately designed to lose about 10 seconds per hour. So, the sync pulse would always make them catch up on the hour.
Hey Girl, love your videos... One Comms tech to another..x
Fascinating and well spoken. Thanks for the informative and unique video
Fascinating as always, thanks!
Excellent presentation. Thanks!
Very interesting!!!! I have always been interested in both watches and clocks and learned something new, thanks for sharing:)
This is great. I can't wait to see it in person.
Connections Museum is likely the coolest, most relevant project on RUclips. I hope I can contribute one day.
Great video and excellent commentary about this type of self-winding clock. I am also a clock buff and have been collecting master and slave clocks for decades. New sub from New Zealand.
Thanks for another great explanation.
You and your channel are awesome, me being from a phone company family love this stuff.
My grandfather was a Bell pioneer and radio tv repair tech after retirement.
As well as my father being a Pioneer, started with Southern Bell, which changed to Bell South, he was an engineer. My sister, uncle, and cousin also worked for Bell, the later two retired with 40 years service.
Of course you know my grandfathers basement looked like a telco museum.
I luckily spent most of my electrician career working phone offices, as my company was a contractor with Bell and AT&T.
I have been in offense that still had party lines in Eastern KY, and seen the conversion from step office to ESS, been in hundreds of CO’s and Radio sites.
Probably the coolest things was traveling south and west and visiting the bunker sites….
Pretty freaky actually… was in one of those when 9/11 happened.
Keep up the great work and interesting stuff.
Once again great video.
I am looking forward to more videos!!! That is really Awesome, I love old clocks, my wife and i have a clock from Germany. Its quite a nice one!!
Haven't seen a self winding clock in a long time. I have a self winding car clock from an old Chrysler that every few minutes would make a single loud click and rewind itself. The synchronization on the clock you described is similar to the Simplex school clocks that use a synchronous motor. Right before the top of the hour, a solenoid powered by the master clock engages and resyncs the clock to the top of the hour.
I have seen quite a few of these and they all seem to run on dry cells while using the telegraph system for synchronization. I was however being under the impression that the clocks in my school could be told to more or less go to the next "hour" at the minimum. I seen remember being a kid and having a power outage while in class (more than one occasion) and when the power came on, the hands on the clock would race around the face to the correct time. Me being into electronics and such, was absolutely fascinated the first time I saw this happen. After seeing it a few times I was theorizing about how that all worked. Anyway, here I am years later, I would love to have them ALL over my house... most times they are extremely hard to find, not working, and or very expensive.
50 years ago I was refurbishing and refitting similar clocks that were taken out of service from air traffic control towers. They had long pendulums that were, in theory, not subject to variations due to temperature and a solenoid that would give the spring a slight wind periodically to maintain the tension. It was a bit of a rig up so that they could be used as ornamental clocks without their usual time sync signal being available. They were quite attractive cabinet clocks.
Another awesome video! Thank you!
Nice that you keep this old technology running, not scared using more modern stuff at the same time.
knowledge of this old tech is the basis for knowledge of modern stuff anyhow.
Hey, nice to see you back! I've been missing you and Astrid :)
That Western Union synchronization system really reminds me of NTP... or maybe the other way round?
And I like your ESP8266 solution :)
I'm glad RUclips took me down this rabbit hole.
Beautiful!
Thanks for te gole explanation...
Great vídeo with perfect sound and Very good Edition...
Bravooo!
Very interesting. My experience with synchronized clocks comes from using an old school master and a couple slave clocks on a model railroad to run "fast time." As the minute hands on the clocks (hopefully) advance with each pulse from the master, it's a (relatively) simple matter to drive the master at a faster clip, say every 10 seconds to speed up time by a factor of 6, etc. Turns out that on the hour the master issues a special pulse to the slaves which releases the slave mechanism so that it slews to its hour position regardless of where it currently is at. This takes care of any slowpoke slaves, resynchronizing them on the hour.
I used to work at a largish government site with secondary clocks in every office and a master clock somewhere in the maintenance department. I ran the first computer network in the building, before anything was connected to the Internet. Twice a year I had to reset the server clock to start/end daylight saving time, and I carefully coordinated with the secondary clock - I'd type the time on the server but not press enter, and as soon as the clock made the buzz-click noise that indicated the top of the hour I'd mash the enter key to set the time as accurately as possible.
A few years later I was reminiscing about the Good Old Days with the maintenance guys, who told me that they carefully adjusted the daylight saving time on the master clock with the time on their computer...
Very interesting. I had no idea how these things worked. I have memories of the school clocks in the 80's and early 90's going wild during synchronization. They were definitely having some problems then! We're very spoiled with NTP these days.
This is wonderful!! Thanks.
OG ntp. This is wild. Thank you for sharing!
Fascinating. I always wondered how the school analog synced clocks worked. Now I know
Wonderful! Thank you, Sarah.
Nice Clock. There was a later Wester Union Clock in the Central central office in Oklahoma City back in the 1970's. It was mounted on a column next to the Time of Day (AUDICHRON). It was AC powered and reset at midnight. The clock and the Time of Day keep good time unless the office was running on back up power generators.
Simplex. That was the brand of the ones in my schools. I'm 63 years old. I loved watching those clocks move from one hour forward or 1 hour back. I didn't know how they did it exactly just that it worked. No doubt I would have loved to take one apart and put it back together as I did with everything else.
When I started working at Disneyland in 1985 they were still using mechanical time clocks and manila cardstock timecards.
The time shacks around the perimeter of the cast member entrances all had syncing clocks which recorded tenths of minutes.
It saved a lot of us getting to the time clock "late" but still had 6 minutes past the hour to clock in and have the timestamp record xx.0 in that day's slot which lasted form minute 0 to 5.
They finally ditched the manual system and went to an electronic mag-stripe ID card system in 1990.
Great find. I worked on private systems in UK not central office but we had Master Clock systems with slaves all round the factory/ hospital / office etc. They pulsed every second to the dumb slaves. After pendulum came Crystal controlled which seemed like magic. I still had two weekends overtime a year driving round the region correcting for British Summer Time/daylight saving and back to GMT.I used the BT Speaking Clock service to manually set them so only accurate to about 1 second though the Masters could be far more accurate.
Hi Alan. T. R. by any chance??
@@hullblerk9597 Its successor Plessey.I came from the ATM side Communication Systems Ltd.
@@alanjones3873 OK Alan. Spent a lot of time at Plessey on various courses. Stayed at the Rockaway.
Reminds me of the German railroad clocks. They have no time-keeping mechanism inside; the second hand is driven by a dumb motor that rotates it once in just under a minute. It stops at the top, and then an impulse from the master clock advances the hands by one minute and allows the second hand to spin again.
Good job on the repair
this was awesome
I remember the clocks at our elementary school did something like this! Once an hour, on the hour they would make that little thunk sound.
Some of them would also (I think intentionally?) Run slow, and would noisily "catch up" by advancing a minute or two, some time during the day.
I have strong ADHD, so I remember paying close attention to when these events occurred, though I only remember about the hourly sync pulse now.
This would have been in the early to mid-90s, in Wisconsin.
Our school had a master clock, when. DST changed, we would look forward to watching the hands move.
keep up the good work
Very interesting - good job
Thank you! Cheers!
ive followed you on tumblr for years, glad to have found your channel.
A modern version of this system is the master atomic clock in Fort Collins, CO, providing the time to radio station WWVB on site, which transmits time of day data to millions of radio controlled "secondary" clocks with internal radio receivers. The mechanical, analog, versions, many from La Crosse Technology, are probably the closest matches to the clock in the museum. In normal operation with the clock receiving a strong enough signal from WWVB, they set themselves after the battery is replaced, then operate as ordinary quartz clocks, setting themselves once a night. The clocks also make DST adjustments based on information encoded in the WWVB signal. If you live in an area that does not observe DST, you can turn off that adjustment.
Actually, these radio controlled clocks match the master clock more closely than the secondary clocks, because they are only set by the time signal once a day. The inexpensive modern quartz oscillator is possibly even more accurate than the very high quality movements in master clocks in these systems. Effectively, there are no secondary clocks and master clocks are deployed instead.
It is fascinating to watch the mechanical analog clock, after the battery is replaced, move its hands to a reference position, wait until it receives valid data, then move its hands to the correct time. There are also digital electronic versions of these clocks, which display a reference time after the battery is replaced, and then "immediately" display the correct time after valid data has been received. Note that it takes one minute to send a complete data frame and the clock may wait for more than one valid frame to be received before setting the time.
Link to a video on youtube: ruclips.net/video/cAHRk_R0F94/видео.html
thanks for the video.
My elementary schools synchronized clocks all stopped working when they turned off analog telephone service in our area. The teachers were actually all quite upset because they had to actually go out and buy clocks for their classrooms.
That sounds like a very well run, very well managed school district.
Excellent video Sarah!!! So impressed on your knowledge of the self Winding Clock and it's functions. I too just won a auction on a self winding clock. It doesn't run yet but with your video I hope to get it going soon..................Thanks again from Sequim, WA
Sarah,
Have you seen Simplex Time Recorder master clocks? I think the 6400 was that last master clock model that they made. I did encounter this model during my time as a fire alarm technician while conducting fire alarm inspections at schools.
In 1984/5 I designed a battery-operated handheld clock used to synchronize/rate the individual field clocks that kept time for seismometers. A small microprocessor operated from an expensive TCXO running at 1.000 MHz +/- 10E-7. On its own, this handheld box would keep time to within ~ 30 ms per day. I added a then-available Radio Shack "time cube" WWV(H) radio receiver & designed an analog filter circuit that could reliably separate the audible WWV "ticks" to be evaluated by software to compare the local clock to WWV, & automatically correct the local clock if it deviated by more than 21 ms. You may think that is a pretty coarse threshold, but don't forget that WWV signals might differ from WWVH signals by over 10 ms of transmitter to receiver path length variations (multi-path ionospheric bounces), so asking for better than ~ 20 ms was unreasonable, and would have added unnecessary dither to the timebase as reception conditions in western North America faded back & forth between WWVH in Hawaii & WWV in Colorado. I learned a lot about timekeeping that year. In ~ 1995 I began using GPS time. My tiny workshop presently has a couple of GPS15L receivers & antennas so that I have reliable access to the one beat-per-second pulse train generated in the receiver. These pulses are good to better than +/- 200 ns error. This is, of course, gross overkill for my wall clocks, but the fanaticism grows stronger every year... LOL
The city I worked in the exchanges all had regular clocks. The billing for toll calls was done in the toll switch. That was called CAMA or Centralized Automatic Message Accounting. That’s where the Master Timer was located. But there was one switch with Centrex service that had LAMA or Local Message Accounting. No master clock. We would call a number in New York every morning and make sure that the clock in the switch was within 6 seconds for accurate billing. And the person on the night shift had to cut the paper tape that recorded the toll calls at 3 AM every day, package it up and send it by Greyhound bus to the billing office located in a different city for processing.
My first job lecturing, in the 1960s: the site had an IBM master-slave clock system. About the third lecture I ever gave, I was looking at the clock at the back of the room, thinking "It's only 25 minutes past the hour, and I'm two-thirds through my material. Slow down." Then, at about 35 minutes past the hour, it suddenly accelerated and whizzed through the next 15 minutes. Nobody had told me that they did that--the folk explanation was water in the cables.
Much more interesting than those manual clocks that run on batteries and need to be set manually.
Here in Leeds, Yorkshire, UK, there is the "Time Ball Building". Its a building built in the 1850s which housed a watch and clock maker. It has a connection to the Greenwich Observatory, Greenwich, London to synchronise the time. At noon the ball would drop and you could use it to set you watch.
I worked on many institutional clock systems .Some of them had paper tape (w/holes) programs.
slightly more complicated than the synchronized clocks used on the railroad for decades - where the last ones are electronic and completely stop at 0 seconds (aka 60) every minute until they get a "go" signal from the master clock. Because they have to wait for the signal they're also always slightly too fast as it takes a few seconds for the signal to arrive. In Denmark those clocks went away when the smartphone became a common thing as the railroad decided there was no need to keep maintaining the many mechanical clocks when everyone have an equally accurate clock in their pocket, so most our stations no longer have clocks at all and merely tell you how long you have to wait for the next train
If I didn’t live 2500 miles away I’d volunteer there in a heartbeat
One of the earliest uses of these clocks was in the Singer office tower in NYC in around 1918. If you don't know about the singer tower I highly recommend watching some videos on it.
Thanks Sarah!
Wish I still had a picture of it, but the Market Central Office in Tacoma (757 Fawcett, TACMWA02) had one of the tall, long pendulum, master clocks on the south wall of the second floor 1931 vintage #1 SXS, next to the MDF. When the office was retired in 1979, that clock went to Bill Smith's collection of classic goodies the night of cutover to the ESS in the building across the street (750 Fawcett, TACMWAFA).
I think the last thing that clock synchronized were the operator position clocks on the forth floor.
I recall at school in the mid 70s being bemused by the clock on the wall periodically and noisily readjusting itself. Didn't know there was a master clock in the principal's office controlling this...
I knew this was going to be interesting but I had no idea it would, no pun intended, tie in that well to the rest of the broader subject matter of communications. Fascinating, but then again what topic of this nature would people like us not find fascinating? Timing signals via simple DC pulses, relays, gears, and lesser timekeeping devices paired to master clocks in such obvious, yet easy to disregard, ways.
Ya gotta love it :)
Also, 3ESS content coming? A W E S O M E ! ! ! ! ! !
this so cool! it makes sense that there would be some sort of way to keep clocks in sync before computers and NTP’s, i just never thought about it before
using a telegram network to keep clocks in sync, and a master clock sending “timing pulses” to sub-clocks - it’s basically a time server before the internet, right?
a wired dumb clock connected to a client clock, that’s connected to a server clock via telegram - it just sounds so cool to me ahhh now i want one too
Ya need brass slot head screws in your desk counter clock those phillip head ones are no Bueno Thanks for a great video
The story of how NTP is used to keep clocks and computers in time is another fascinating topic. Don't forget the Heathkit WWV clocks.
My high school used a system of synchronized clocks from IBM. The master clock was in the administrative part of the building and slave clocks were in each classroom. When we switched from DST to standard time or vice versa, they changed the time on the master clock but the slave clocks would "go crazy." I think the bells for changing classes rang on time after the master clock was changed, so that part was orderly. However, teachers had to rely on their watches instead of the classroom clock to make sure lessons were proceeding on time. After about a week of, probably, furiously straightening out systems for other customers, an IBM technician would make a service call and straighten things out for us.
My internet search has found synchronized clock systems from IBM, but I haven't been able to match up the system that my high school used.
Telephone companies needed accurate clocks to do billing. The rate for an entire call depended on the rate period when the call started.
Rates for phone calls have, at least since the 80s, worked as described in the phone books of the time: "A phone call beginning in one rate period and continuing into another rate period will be billed at the rates applicable to both periods"
I have one of these. The back plate is stamped in ink WECO KS-1928 WECo insp 11773. There are two screw contact boards at the top of the back plate. Left is 1 - 4, right 5 - 8. 1 and 2 are the 24 VDC for the winder. 3 and 4 are the 6 second contacts. Someone wrote in pencil “POD clocks small” below the terminals. 5 and 6 are the 24 VDC hourly sync pulse input. The sync coil is 400 Ohms, so I assume it is 24 Volt. The 3 Volt sync coils are about 20 Ohms. Contacts 7 and 8 connect to another interrupter which is strange. It generates pulses at 10, 20, 30, 40 seconds. Someone wrote in pencil “large sec clocks” below the terminals. Contacts 3 and 4, also 7 and 8 have knife switches which allow their circuits to the movement to be opened as well as momentary key switches which allow for manual pulsing.
The newer type F movements in these clocks bear a lot of similarity to movements made by Seth Thomas. Earlier movements were outsourced to E. Howard, Seth Thomas, and possibly others. The early movements used an unusual rotary motor which was modular and easily swapped for servicing. The motors could be temperamental to adjust (personal experience) and were probably thought to be too technical for field service workers to deal with. The vibrators are simpler and more reliable, thus integrated into the movement. The whole type F movements were easily swapped and sent back for depot servicing. The movement and serial number tag were swapped out together, and clocks may have had several movement swaps, so it can be difficult to tell exactly when a particular SWCC clock was made. Over all, the SWCC type F is a very clever design and could run for many years in poor conditions. The hourly sync feature meant that the pendulum did not need to be super accurately adjusted and time only needed to be initially set within about +/- 2 minutes. Oddly, there is a lock-out that that prevents synchronization if the minute hand is too far off the correct time.
I have no further information beyond what Sarah said in the video.
The winding relay is really a form of a buzzer.