[time-nuts] Re: measuring tiny devices
Hi Ed: You might surf the Accessories Catalog for Impedance Measurements. https://www.keysight.com/us/en/assets/7018-06727/brochures/5965-4792.pdf They have a number of SMD fixtures for 4-terminal pair LCR meters. https://prc68.com/I/Z.shtml#KeyDocs -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message On 5/25/22 3:16 PM, ed breya via time-nuts wrote: Thanks Mike, for info on LCR alternatives. It's good to know of others out there, if needed. I have an HP4276A and HP4271A. The 4276A is the main workhorse for all part checking, since it has a wide range of LCZ, although limited frequency coverage (100 Hz - 20 kHz). The 4271A is 1 MHz only, and good for smaller and RF parts, but very limited upper LCR ranges. I think it works, so I can use it if needed, but would have to check it out and build an official lead set for it. I recall working on it a few years ago to fix some flakiness in the controls, so not 100% sure of its present condition. The main difficulty I've found in measuring small chokes is more of probing/connection problem rather than instrument limitation. For most things, I use a ground reference converter that I built for the 4276A many years ago. It allows ground-referenced measurements, so the DUT doesn't have to float inside the measuring bridge. The four-wire arrangement is extended (in modified form) all the way to a small alligator clip ground, and a probe tip, for DUT connection, so there is some residual L in the clip and the probe tip, which causes some variable error, especially in attaching to very small parts and leads. When you add in the variable contact resistance too, it gets worse. Imagine holding a small RF can (about a 1/2 inch cube) between your fingers, with a little clip sort of hanging from one lead, and pressing the end of the probe tip against the other lead. All the while, there's the variable contact forces, and effects from the relative positions of all the pieces and fingers, and the stray C from the coil to the can to the fingers. I have pretty good dexterity, and have managed to make these measurements holding all this stuff in one hand, while tweaking the tuning slug with the other. I had planned on making other accessories like another clip lead to go in place of the probe tip, but not yet built. I also have the official Kelvin-style lead set that came with the unit, so that's an option that would provide much better accuracy and consistency, but the clips are fairly large and hard to fit in tight situations, and the DUT must float. Anyway, I can make all sorts of improvements in holding parts and hookup, but usually I just clip and poke and try to get close enough - especially when I have to check a lot of parts, quickly. The other problem is that the 4276A is near its limit for getting measurements below 1 uH, with only two digits left for nH. The 4271A would be much better for this, with 1 nH vs 10 nH resolution. If I get in a situation where I need to do a lot of this (if I should get filter madness, for instance), then I'll have to improve the tools and methods, but I'm OK for now, having slogged through it this time. You might check out the NanoVNA - people have made a variety of novel fixtures for measuring small parts (i.e. 0604 SMTs) It certainly has the measurement frequency range you need. The trick is figuring out whether you want to do a series or shunt measurement, and that sort of depends on the reactance of your device at the frequency of interest. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-le...@lists.febo.com ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-le...@lists.febo.com
[time-nuts] The Newest Second: NIST-F2
Hi: https://www.nist.gov/si-redefinition/second/second-present NIST Launches a New U.S. Time Standard: NIST-F2 Atomic Clock https://www.nist.gov/news-events/news/2014/04/nist-launches-new-us-time-standard-nist-f2-atomic-clock First accuracy evaluation of NIST-F2 (behind paywall) https://iopscience.iop.org/article/10.1088/0026-1394/51/3/174 -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: W.E. 38C oscillator
Hi John: Can you post a photo or two? -- Have Fun, Brooke Clarke, N6GCE https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message Growing dangerously close to the ripe old age of 80 and it becoming obvious that I have little to no chance of regaining my youth, I am in the process of separating the treasures I have collected into piles, primarily items that I may have time to play with and those that I have little time for. I have discovered a pair of Western Electric 38C oscillators that are marked Freq. 1024.000 KC. Having worked in the computer industry for 30 years, I suspect the frequency was my motivation in saving them. Anyone know anything about them, where they were used and for what? They have an ovenized oscillator, well insulated(for the time), and a compartment with several phenolic hardwired boards. A Google search turns up nothing. John K0GCJ ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Time Signal Transmitter (low power)
Hi Anthony: For efficient transmission of radio signals the antenna should be at least 1/4 wavelength in size. At 60 kHz a wavelength is 5,000 meters so a 1/4 wave is 1250 meters (4100 feet). If the antenna is smaller than 1/4 wavelength the efficiency goes down. So if you were to wrap a room/house with a coil of wire and with an impedance match drive it with a 60 kHz signal the signal would fall off very quickly. There's a license free band in the US between 160 and 170 kHz (1750 meters) where you are limited to a 50 foot antenna and one Watt input to the transmitter. It's quite a challenge to be heard a hundred miles away. Instead of the 37 Ohms antenna impedance of a 1/4 wave vertical you have an antenna resistance that's a thousand times smaller. That means the effective radiated power is in the milliwatts. -- Have Fun, Brooke Clarke, N6GCE https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message G'day time nut friends I wonder if one of you could point me in the right direction on how to purchase (if one exists) a Time Signal Transmitter for use at the local level (range 20m) for synchronising watches and radio clocks using the various standard radio frequencies? And for the transmitter itself to receive / synchronise it's time using NTP? I am in Australia and we are out of range for the normal transmissions... Kind regards to you all Anthony Dunne Sydney, Australia ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Where do people get the time?
Hi Bill: Here are a couple of web pages on the Western Union clocks made by the Self Winding Clock Co: https://prc68.com/I/SWCC.shtml https://prc68.com/I/SWCC2.shtml I think it was more like 200 Volts and it's important because the time constant of an L - R circuit is L/R, so by adding a series resistor the loop time constant can be very much shortened. A common mistake is using a low voltage which makes the action very sluggish, sometimes to the point of not working. -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message I have had one of those Western Union clocks for 30 years and it is still working. Originally powered by 2 # 6 dry cells that ran the clock for years. Now powered by 2 D cells that run it for a year. To reset the time WU would stop all traffic on their wire from 1159 to 1201 and at 1200 send a hundred volts down the wire for a few seconds. That would activate a solenoid that would reset the hour hand to noon. When WU decided they did not want to be in the time business they told their customers they could keep the clocks. That afternoon many clocks walked out of the offices! Everything you wanted to know about Self Winding Clock Company can be found in "American Clocks Volume 2" by Tran Duy Ly starting on Page 177. I have a copy of instructions for Model F from the Self Winding Clock Co Engineering Department that I can send to any one that is interested. My clock was restored by Ken's Clock shop who specializes in these clocks. 73, Bill, WA2DVUCape May, NJ On Monday, December 27, 2021, 07:02:09 AM EST, Thomas D. Erb wrote: years ago I was out a large clock installation in NYC - written on the wall was a note - before noon tune to a specific shortwave frequency to listen to the noon type signal. Western Union used to distribute time over their telegraph network for a small fee - in connection with the Self Winding Clock Company The power company (still does) keeps line frequency accurate to a time standard. Henry Warren got this standardized - I believe Tesla proposed it. Cell phone towers all have GPS receivers - there are ways to get time off them. We now use GPS receivers everywhere you can get a nmea sentences that has UTC time. Thomas D. Erb p: 508-359-4396 f: 508-359-4482 a: 97 West Street, Medfield, MA 02052 USA e: t...@electrictime.com w: www.electrictime.com Tower & Street Clocks Since 1928 ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Why do have OCXO a Vref output?
Hi: I'd second this. When I was working at HP on the Kobe Instrument Division products (component testers) the 4352S VCO tester had a very special power supply for the tuning voltage that was extremely clean so as not to detract from the VCO under test. -- Have Fun, Brooke Clarke, N6GCE https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message I've always assumed this is because they need to know the reference is clean and under the OCXO manufacturer's control if it's to meet specs. If the user had to supply the reference there's no knowing how clean it is. Andy www.g4jnt.com On Thu, 23 Dec 2021 at 17:47, Attila Kinali wrote: On Thu, 23 Dec 2021 14:42:27 +0100 Wilko Bulte wrote: A quick experiment learned that the OCXO freq responds to the EFC voltage. So, looks like the Vref circuit in the OCXO has died. A stupid side question: Why do have OCXO a Vref output in the first place? I can see that some form of reference might make stabilizing the power in the crystal easier, but that still wouldn't make it necessary to have an actual reference output. And related to that: Would supplying the voltage reference externally, in case of a broken Vref output, work for whatever is inside that needs this reference voltage? Attila Kinali -- The driving force behind research is the question: "Why?" There are things we don't understand and things we always wonder about. And that's why we do research. -- Kobayashi Makoto ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Clock displays -- eye response
Hi Jim: Interesting paper on flashing temporal response. "Have Quick" is primarily a spread spectrum radio protocol but it also includes a time transfer/setting protocol. The early Trimpack GPS receivers included a time setting output. https://prc68.com/I/Trimpack.shtml The PLGR & DAGR output the HQ digital data used to set the time in the O-1814 Rb. The O-1814 was part of the Program Pacer Speak System so that inbound bombers coming from far away would hear the HQ radio transmissions. https://prc68.com/I/MT6250.shtml There are different flavors of HQ time protocol, but the newer one just adds data after the older one so is backward compatible. It's tricky to see the data. I needed to use an SRS DG535 to delay the scope trigger so that I could use a very fast sweep speed. https://prc68.com/I/DAGR.shtml#HQ1PPS - scroll down a little to see the HQ setup. -- Have Fun, Brooke Clarke, N6GCE https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message On 12/10/21 12:31 PM, Brooke Clarke via time-nuts wrote: Hi Hal: There has been some recent research into illusions related to sight and sound. https://en.wikipedia.org/wiki/McGurk_effect - related to speech and search "audio optical illusion" I like a crisp "tick" for clock human synchronization. I wonder why there has not been more done with military "Have Quick" for time synchronization? https://en.wikipedia.org/wiki/HAVE_QUICK HAVE QUICK was a very early hopping spread spectrum system and was long since superseded by SINCGARS and other systems in the 1980s. I don't know that it is a "source" of time. There was a whole set of systems for loading "time" into these frequency hopping systems, since all manner of their synchronization behavior depended on time. And in usual DoD/NATO fashion, forward and backward compatibility was often required, so you'd have a way to sync any two random radios in a battlefield situation. Cryptographic keying is also often time based, as are frequency nets (local interference, keeping the other guy guessing, or propagation changes) Synchronization is the "hard part" of most spread spectrum systems both Direct Sequence (PN codes) and Frequency Hopping, and that's where most of the classified stuff is - how do you synchronize reliably, how do you prevent the synchronization from being spoofed or jammed. A naive FH approach is to have a "hailing channel" and the first person transmits there, and the other person hears it, listens to a sync pattern, and then commence hopping together. This works for point to point between two stations, but doesn't work very well when you have multiple stations, not all of which can hear each other. GPS would have been a godsend back then (although it's not very good from an Anti Jam standpoint). Dixon, in the seminal tome "Spread Spectrum Systems" kind of makes an offhand comment that synchronization is the challenging part, and then moves on "assuming we have synchronized". It's been a part of the PLGR and DAGR GPS receivers and I expect also for the military embedded versions for a long time. https://prc68.com/I/PLGR.shtml#Time https://prc68.com/I/DAGR.shtml#HQ1PPS Also things like the O-1814/GRC-206 Reference Frequency Rb Oscillator make us of it. https://prc68.com/I/O1814.shtml I don't know that they make use of it, rather, they can provide sync TO a HAVE QUICK radio. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Clock displays -- eye response
Hi Hal: There has been some recent research into illusions related to sight and sound. https://en.wikipedia.org/wiki/McGurk_effect - related to speech and search "audio optical illusion" I like a crisp "tick" for clock human synchronization. I wonder why there has not been more done with military "Have Quick" for time synchronization? https://en.wikipedia.org/wiki/HAVE_QUICK It's been a part of the PLGR and DAGR GPS receivers and I expect also for the military embedded versions for a long time. https://prc68.com/I/PLGR.shtml#Time https://prc68.com/I/DAGR.shtml#HQ1PPS Also things like the O-1814/GRC-206 Reference Frequency Rb Oscillator make us of it. https://prc68.com/I/O1814.shtml -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message Does anybody have numbers for how long it takes for a visual signal to get into your brain? I think it's around 250 ms for a human to push a button when a light goes on. Less if the penalty for false pushes is low. I don't have a handy URL to back that up. But that's in and back out. I assume the "in" step is only part of that. Are flashes out of the corner of your eye that might indicate danger faster? If 2 lights go on at close to the same time, how far apart do they have to be before you can notice that one goes on first? ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Clock Display on Linux: Update
Hi Adam: Years ago I built a hardware clock display settable to 1 ms based on a PIC 16F88 microcontroller. The idea was to attach these to frequency standards thus making them into precision clocks. https://www.prc68.com/I/PRC68COM.shtml#07092006 There are some tricks to writing PIC assembly code in such a way that the number of instructions is always the same. TVB has also done some PIC coding. -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message Thanks to everyone who responded to my first thread about getting a good clock display on a Linux system. I want to try out some of those ideas that give a higher-end accuracy, but in the meantime I've hacked together some basic stuff in Python that is accurate within a few ms. The main problem with GUI stuff in Python is that sleep() functions, or their implementations in various GUI libraries, can definitely not be trusted. In fact, I tested tkinter's after() function, which functions like your basic sleep() function in between display updates, and it drifts on the order of 500ppm (i.e. every two seconds it loses/gains a ms), which is quite bad. The key to getting a good clock which is consistently accurate to system time within as little as 5ms (and therefore if system time is accurate to +/- 10ms with NTP you have an overall accuracy of 15ms, at worst), is just to adjust the clock periodically based on the offset from the display updates to the system time. In other words, every ten seconds or so, instead of doing sleep(1000), you can just sleep(1000 - offset). (The units here are ms). This worked for me quite well. +/- 5ms is quite sufficient for a system which itself is only accurate within 10ms with NTP. Now, I just need to figure out how to get a good display going for a higher accuracy device, in particular a PPS-Raspberry Pi setup I am trying to get working. I'm sure some people here have done something similar, but I figured I'd share. Adam ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: FS740 Thoughts?
Hi Dana: My PRS10 is a couple decades old and I use it in the 1PPS locking mode. But that may not have been the default. Maybe the surplus units just need the correct jumper change. https://prc68.com/I/PRS10.shtml -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message But if you can stand the ADEV hump around 2 sec, the PRS-10 is delightful. BTW, the ordinary factory new PRS-10 does provide for direct locking to 1 PPS, but many of the available surplus units had that feature removed. Tne new PRS-10's sold for years for $1595, but I see that it has gone up to $1695 since I had last checked. Dana On Wed, Nov 17, 2021 at 9:52 AM Bob kb8tq wrote: Hi In this case it’s not thermal. I’ve tested a ton of parts in the same environment ( maybe not 2,000 pounds but several hundred OCXO’s ). The PRS-10 gives you that hump at 2 seconds no matter what you do. It’s part of the basic design of the unit …. Bob On Nov 17, 2021, at 10:16 AM, Matt Huszagh wrote: Bob kb8tq writes: I have a 740 as do others on the list. The big gotcha is the OCXO in the device. It has various quirks that limit the performance of the device. The ADEV plot they show for the OCXO is a “sometimes / maybe / might” sort of thing. One of the “get to it eventually” projects here is to see if it can be replaced with something that has better ADEV performance. Good to know. Have you tried disciplining the PRS-10 in one of these units? Based on Dana's comments, it sounds like this may not exhibit the same ADEV susceptibility to the thermal environment. Matt ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Potting compound advice needed
Hi Jim: Be careful with RTVs. Some out gas acid that attacks metal, even gold plated metal. Guess how I know that. -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message On 11/10/21 2:40 PM, Richard (Rick) Karlquist wrote: I am looking for help choosing a potting compound that has the following properties: 1. Good for 5,000VAC @ 1 MHz 2. Low RF losses. 3. Low permittivity is preferred 4. Low tempco of permittivity is a want. 5. Something I can implement in my home shop without access to a vacuum pump etc. is a want. What about curing? Is temperature cure (put it in an oven) ok? or do you need room temp cure? Silicones are usually pretty good, RF wise. But you need to check the filler and exact composition. I found a two component silicone that has epsilon 2.5 used for RF potting, 15kV/mm breakdown. https://vitrochem.com/wordpress/wp-content/uploads/2020/10/Two-Component-Condensation-Silicone.pdf they say nothing about the dissipation. Aha. RTV12 from Momentive - clear - epsilon 3.0, tan d (at 1kHz) is 0.001, 400 V/mil - This stuff is pretty common, but I can't find any higher frequency permittivity info, which is odd. Someone somewhere probably built something and measured it. Diallyl Pthalate is what they use in connectors - it's a thermosetting resin with good electrical properties. https://www.cosmicplastics.com/products/dap/ Picking the first one in the list 224 DAP - 360 V/mil, so for your 5kV, you'd need ~14 mils. (most plastics are in this range) Epsilon is kind of high 3.5, tan D is 0.01? Is that good enough for you dissipation wise? There's lots of kinds with various fillers. A common way to reduce epsilon and tan d is to mix in microspheres. Some epoxies are also good. Rogers not only makes laminates for circuitboards they also produce the epoxy from which they are made We use tons of arathane and solithane at JPL (both are urethanes), but I don't know if we pot RF circuits in araldite. Huntsman makes the "ara???" materials https://huntsman-pimcore.equisolve-dev.com/Documents/US_2019_High_Performance_Components_Selector_Guide.pdf one thing is that we store this stuff at -80C, but I don't know if that's after mixing or if it's shipped that way (in dry ice). masterbond.com -> give them a call or email EP110F80-1 is a 2 part epoxy with e=2.69@1MHz, so it's probably reasonably low loss. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: NBS 1000 CPS Tuning Fork Standard?
Hi Eric: While the paragraph on "frequency" (pdf page 49) has a detailed description of " Pendulum oscillations, see Fig 16" that has reference letters, when I look at Fig 16 I do not see those letters. So was hoping someone recognized that equipment. It's interesting to read the description of time at NBS in 1927. -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message Fig 16 refers to Fig 22 for “time”. Fig 22 shows a Riefler clock and pendulum with electrical impulsing — discussed further on page 44. A search of the entire document for references to “fig. 16” brings up page 40, which explains both Fig 16 and 17 at a high level. On 2021 Oct 14, at 18:59 , Brooke Clarke via time-nuts wrote: Hi: Somehow I got dropped from the mailing list around March 9, but have been added back. Hi: I recently stumbled onto this at the Wiki page for tuning forks: https://en.wikipedia.org/wiki/Tuning_fork#In_clocks_and_watches Showing an NBS 1,000 CPS standard. related to a discussion on the GreenKeys list server about the history of the tones used for radio teletype. https://prc68.com/I/TuningForks.html#AFSK-Tones and that lead to the NBS 1927 Yearbook pages 40 and pdf page 408 https://prc68.com/I/TuningForks.html#NBS_1000_CPS_Standard https://www.google.com/books/edition/Standards_Yearbook/5h_9yYrnBCYC?hl=en=0 Fig 16 (pdf pg 408) "Pendulum oscillations" and Fig 17 "Tuning-fork vibration". Can someone explain what's shown in Fig 16 on pdf page 408? Maybe a Shortt pendulum can sitting on a shelf off the stack of bricks? -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] NBS 1000 CPS Tuning Fork Standard?
Hi: Somehow I got dropped from the mailing list around March 9, but have been added back. Hi: I recently stumbled onto this at the Wiki page for tuning forks: https://en.wikipedia.org/wiki/Tuning_fork#In_clocks_and_watches Showing an NBS 1,000 CPS standard. related to a discussion on the GreenKeys list server about the history of the tones used for radio teletype. https://prc68.com/I/TuningForks.html#AFSK-Tones and that lead to the NBS 1927 Yearbook pages 40 and pdf page 408 https://prc68.com/I/TuningForks.html#NBS_1000_CPS_Standard https://www.google.com/books/edition/Standards_Yearbook/5h_9yYrnBCYC?hl=en=0 Fig 16 (pdf pg 408) "Pendulum oscillations" and Fig 17 "Tuning-fork vibration". Can someone explain what's shown in Fig 16 on pdf page 408? Maybe a Shortt pendulum can sitting on a shelf off the stack of bricks? -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
