Re: [time-nuts] Antique precision timing device without electronics

[iovane--- via time-nuts]

This is mine, used to calibrate some aircraft related equipment:

https://www.flickr.com/photos/103726899@N08/33326340242/in/dateposted-public/ 

and its diagram:

https://www.flickr.com/photos/103726899@N08/33482556075/in/dateposted-public/

iov


>Messaggio originale
>Da: "Mike Seguin" 
>Data: 16/03/2017 22.33
>A: "Discussion of precise time and frequency measurement"
>Ogg: Re: [time-nuts] Antique precision timing device without electronics
>
>Very interesting use of a tuning fork.
>
>I have only seen this once before. I have the tuning fork used with an 
>Ampex Model 300 reel to reel tape machine. The tuning fork was used as a 
>reference in the power supply that drove the capstan motor for accurate 
>speed.
>
>It's 60 Hz not 25 Hz. It's marked B E Eisenhour. Patent is here:
>
>https://www.google.com/patents/US1880923
>
>Pic is here:
>
>https://www.dropbox.com/s/opmxr521qqkx76r/60%20Hz%20Fork.jpg?dl=0
>
>Mike
>
>On 3/16/2017 2:04 PM, Bill Hawkins wrote:
>> Hi Morris,
>>
>> If there's no active devices (and you'd be sure to see them, not solid
>> state) where does the power to operate the motor come from? Is it the
>> same contacts that drive the fork?
>>
>> It's amazing that there is high Q when contacts must be operated by the
>> fork.
>>
>> Did it come with instructions for setting the weights at the end of the
>> fork tines?
>>
>> Best regards,
>> Bill Hawkins
>>
>> -Original Message-
>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Morris
>> Odell
>> Sent: Thursday, March 16, 2017 4:23 AM
>> To: time-nuts@febo.com
>> Subject: [time-nuts] Antique precision timing device without electronics
>>
>> Hi all,
>>
>> I was recently asked to resurrect this interesting device by a colleague
>> who collects antique scientific instruments. It's a "Chronoscope" made
>> by the H. Tinsley company in London in the early 20th century and used
>> to measure time intervals with the precision of those days. It's large
>> and heavy in a polished wooden case with a top deck that hinges up to
>> reveal the innards.
>>
>> The timing reference is a large tuning fork about 30 cm (1 foot) long
>> and running at 25 cps. It's normally in a glass fronted housing (removed
>> for the video) that includes a pair of hinged mechanical arms for
>> starting it. It's maintained in oscillation by an electromagnet and
>> contact arrangement powered from a 12V DC supply. The fork amplitude is
>> controlled by a rheostat - too much and the tines impact on the magnet.
>> The video frame rate makes the fork look slower than it actually is. I
>> was able to extract a signal and measure the frequency with a modern GPS
>> disciplined counter - it's 0.007% off its specified 25 Hz! The frequency
>> is too low for my HP 5372A so I was not able to easily get an idea of
>> stability or do an ADEV measurement. The fork has quite a high Q and
>> takes over a minute to stop oscillating after the power is turned off.
>> There's a built in higher voltage AC power supply, probably a mains
>> transformer, potted in beeswax in a polished wooden box inside that is
>> intended to
>>   energise a large neon strobe lamp used to adjust the fork.
>> Unfortunately the lamp was not with the unit and is no doubt
>> irreplaceable.
>>
>> The 25 Hz signal is filtered by an LC network  and used to run a
>> synchronous motor in the Chronoscope unit. Synchronous motors not being
>> self-starting, you need to tweak a knob to get it going - there's a joke
>> in there but I can't for the life of me think what it could be ?? The
>> "Contact" switch and associated socket on the back controls an
>> electromagnetic clutch that connects the clockwork counter mechanism to
>> the motor and the contact "on" time is indicated on the dials with 10 mS
>> resolution.
>>
>> There's not a single active device in there and after a clean and lube
>> it runs very nicely from a modern 12V DC plugpack. My friend is very
>> pleased with it and it will take pride of place in his collection.
>>
>> I'd be interested to know if any time nuts have knowledge or experience
>> of this lovely instrument.
>>
>> A video of it is at  https://youtu.be/i5S8WS9iN_E
>>
>> Enjoy!
>>
>> Morris
>>
>>

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Re: [time-nuts] Smart Phone time display accuracy...?

[Chris Albertson]

> Not to gloat, but my Android phone is always spot on.  I have a GPS time
> app that shows the difference between GPS and phone time and it's always in
> the tenths of a second area.

"tenths of a second" is "spot on"?   No way.   That is a difference
that is perceivable to humans.

Apple claims in their spec that the iPhone when paired with a watch is
worst case within 50 milliseconds which is not really that good but is
acceptable for a watch because it is just under what most people can
notice.
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Re: [time-nuts] Vectron 233Y5317 OCXO data 250 Mhz

[Jeff AC0C]

Thank you gentlemen!

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-Original Message- 
From: Bob Raker

Sent: Thursday, March 16, 2017 6:48 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Vectron 233Y5317 OCXO data 250 Mhz

Jeff,

You have a 250MHz VCXO

+/100 ppm deviation for +/-5V

12V supply

Here are general specs:

https://www.vectron.com/products/vcxo/co-233vf_233vfw.htm

73,
BR




On Thu, Mar 16, 2017 at 4:51 PM, Jeff AC0C  wrote:


Looking for a datasheet for this OCXO, or for the general family.

Thanks!

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

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Re: [time-nuts] Smart Phone time display accuracy...?

[Hal Murray]

kb...@n1k.org said:
> Under normal conditions, the Gold Codes on CDMA are synchronized to < 100
> ns.

Is that a full time synchronization, or something like a PPS where they can 
get the ticks lined up but not know the time for any individual tick?


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Re: [time-nuts] Smart Phone time display accuracy...?

[John Allen]

There is a NTP app for the iPhone called Gorgy Atomic Timing Clock.
You can choose from about 6 different NTP servers and it has an audible tick.  
It does not (can not) set the iPhone's clock.
https://itunes.apple.com/us/app/atomic-clock-gorgy-timing/id295302256?mt=8

It was free, but now is $1.99.

John K1AE Bolton, MA

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp
Sent: Thursday, March 16, 2017 6:09 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Smart Phone time display accuracy...?

Hi

Under normal conditions, the Gold Codes on CDMA are synchronized to < 100 ns. 
It’s only when something goes wrong
that they drift out to the 10 us range. Once they get there, the transmitter 
needs to shut down. Unfortunately, there is no
mandatory connection between the transmitter time source for the output coding 
and the time reported to the phone. Yes,
that is really weird. 

Bob

> On Mar 16, 2017, at 1:06 PM, Mike Garvey  wrote:
> 
> CDMA mobile telephony needs system synchronization to +/- 10 uS in order to 
> smoothly handoff a moving client from one cell to the next. Most systems use 
> GPS to maintain this 10 uS.  This says nothing about how bad it could get 
> after that.
> Mike
> 
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Baker
> Sent: Wednesday, March 15, 2017 22:33
> To: time-nuts@febo.com
> Subject: [time-nuts] Smart Phone time display accuracy...?
> 
> Hello, Time-nutters--
> 
> Any thoughts on what the likely accuracy of smart phone time
> displays might be?   I am thinking that the stacking of delays
> along the path to its receive antenna plus any internal processing delays 
> would accumulate to some unknown degree.  Any thoughts on this?
> 
> Mike Baker
> *
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Re: [time-nuts] Smart Phone time display accuracy...?

[Tim Lister]

On Thu, Mar 16, 2017 at 2:32 PM, Severin Haas  wrote:
> The German PTB has a nice widget (https://uhr.ptb.de) to see the actual
> time + deviation ("Abweichung"). Can not test this from another location
> than UTC+1h, but probably it works at your location.
> Does anybody of you know how they are measuring the time deviation? Some
> JavaScript Voodoo?
>
>
It's says '8h+/-15ms' from here in California with an uncertainty (if
I guess the German correctly) of 115ms. Not sure how it's working it
out; ping's seem to be being filtered close to the final destination.
The last hop that reported was about 175ms.

Tim
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Re: [time-nuts] Vectron 233Y5317 OCXO data 250 Mhz

[Bob Raker]

Jeff,

You have a 250MHz VCXO

+/100 ppm deviation for +/-5V

12V supply

Here are general specs:

https://www.vectron.com/products/vcxo/co-233vf_233vfw.htm

73,
BR




On Thu, Mar 16, 2017 at 4:51 PM, Jeff AC0C  wrote:

> Looking for a datasheet for this OCXO, or for the general family.
>
> Thanks!
>
> 73/jeff/ac0c
> www.ac0c.com
> alpha-charlie-zero-charlie
>
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Re: [time-nuts] Vectron 233Y5317 OCXO data 250 Mhz

[Bob Camp]

Hi

Not an OCXO, but it’s a Vectron 233

https://www.vectron.com/products/xo/co-233_233h.htm

The 233’s are all un-compensated XO’s

Bob

> On Mar 16, 2017, at 4:51 PM, Jeff AC0C  wrote:
> 
> Looking for a datasheet for this OCXO, or for the general family.  
> 
> Thanks!
> 
> 73/jeff/ac0c
> www.ac0c.com
> alpha-charlie-zero-charlie
> 
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Re: [time-nuts] Smart Phone time display accuracy...?

[John Hawkinson]

There is a lot of...problematic...advice here. For instance:

Gary Woods  wrote on Thu, 16 Mar 2017
at 18:09:26 -0400 in :

> Not to gloat, but my Android phone is always spot on.  I have a GPS
> time app that shows the difference between GPS and phone time and
> it's always in the tenths of a second area.

Notice Gary doesn't specify which brand of Android phone, much less
the specific model and carrier. This matters...a lot.

For instance, my Verizon Samsung Galaxy S7 is regularly off by 300-700ms,
and sometimes off by more than a second. A colleague's cell phone
is regularly off by about 10 seconds. On the other hand, another colleague's
Nexus {i forget what model} seems good to 10 ms.

It's not clear to me how Android phones set their own time from the
cell network, but I think the actual answer is "in many cases, not
very well."

The "ClockSync" android app will compare your phone's time to NTP,
which does a pretty decent job.
The "GPS Time" and other similar apps will compare your phone's time to
UTC as derived from your phone's GPS receiver, although I think this is
necessarily imprecise not only because of multipath but because of software
issues between the GPS receiver and the phone. *handwave*


I can't speak for iPhones, but for Android phones, it's really
extremely hit-or-miss, and highly variable, both between models and
even with a given phone from day to day. And if your threshold is
something like half a second, you might think your phone is always
good enough, and then have a rude awakening (I did!) when one day it's
off by >1 second.

--jh...@mit.edu
  John Hawkinson
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Re: [time-nuts] Smart Phone time display accuracy...?

[Bob Camp]

Hi

Under normal conditions, the Gold Codes on CDMA are synchronized to < 100 ns. 
It’s only when something goes wrong
that they drift out to the 10 us range. Once they get there, the transmitter 
needs to shut down. Unfortunately, there is no
mandatory connection between the transmitter time source for the output coding 
and the time reported to the phone. Yes,
that is really weird. 

Bob

> On Mar 16, 2017, at 1:06 PM, Mike Garvey  wrote:
> 
> CDMA mobile telephony needs system synchronization to +/- 10 uS in order to 
> smoothly handoff a moving client from one cell to the next. Most systems use 
> GPS to maintain this 10 uS.  This says nothing about how bad it could get 
> after that.
> Mike
> 
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Baker
> Sent: Wednesday, March 15, 2017 22:33
> To: time-nuts@febo.com
> Subject: [time-nuts] Smart Phone time display accuracy...?
> 
> Hello, Time-nutters--
> 
> Any thoughts on what the likely accuracy of smart phone time
> displays might be?   I am thinking that the stacking of delays
> along the path to its receive antenna plus any internal processing delays 
> would accumulate to some unknown degree.  Any thoughts on this?
> 
> Mike Baker
> *
> ___
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> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Re: [time-nuts] Smart Phone time display accuracy...?

[Mark Spencer]

>From occasional observations of my IPhone 5 using the emerald sequoia emerald 
>time application the "within 50 milliseconds" claim seems quite reasonable to 
>me.

Mark Spencer




> On Mar 16, 2017, at 12:31 PM, Chris Albertson  
> wrote:
> 
> Apple Support claims "within 50 milliseconds of the definitive global
> time standard".  At least that is what Apple gives in their spec.
> 
> It might use difference source depending on which radios are enabled.
> The phone does have GPS and a cell network radio and both can be used
> for time.But on a phone these radios are powered up and down as
> needed.   I think best just to accept Apple's spec.
> 
> Again it would be fun to measure.  There is an API call to get the
> system time.  One could write a simple app to send this out
> 
> Harder to know the specs on Android as there are so many manufactures
> and versions and price points
> 
>> On Thu, Mar 16, 2017 at 10:06 AM, Mike Garvey  wrote:
>> CDMA mobile telephony needs system synchronization to +/- 10 uS in order to 
>> smoothly handoff a moving client from one cell to the next. Most systems use 
>> GPS to maintain this 10 uS.  This says nothing about how bad it could get 
>> after that.
>> Mike
>> 
>> -Original Message-
>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Baker
>> Sent: Wednesday, March 15, 2017 22:33
>> To: time-nuts@febo.com
>> Subject: [time-nuts] Smart Phone time display accuracy...?
>> 
>> Hello, Time-nutters--
>> 
>> Any thoughts on what the likely accuracy of smart phone time
>> displays might be?   I am thinking that the stacking of delays
>> along the path to its receive antenna plus any internal processing delays 
>> would accumulate to some unknown degree.  Any thoughts on this?
>> 
>> Mike Baker
>> *
>> ___
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>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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>> 
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>> and follow the instructions there.
> 
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] Smart Phone time display accuracy...?

[Gary Woods]

On Thu, 16 Mar 2017 13:16:11 -0700, you wrote:

>My iPhone seems to be accurate to 5 minutes or so.  There are two of them in 
>my 
>house and they never agree.  My computer is saying 1:15 PM local time, my 
>iPhone 
>says 1:20PM

Not to gloat, but my Android phone is always spot on.  I have a GPS time
app that shows the difference between GPS and phone time and it's always in
the tenths of a second area.


-- 
Gary Woods O- K2AHC   Public keys at home.earthlink.net/~garygarlic, or get 
0x1D64A93D via keyserver
fingerprint =  E2 6F 50 93 7B C7 F3 CA  1F 8B 3C C0 B0 28 68 0B

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Re: [time-nuts] Antique precision timing device without electronics

[David]

I think Bob Pease of National Semiconductor fame mentioned looking for
the earliest use of phase locked loops and finding a reference to a
European clock maker who had a master pendulum clock with a mechanical
coupling that phase locked newly built clocks when left connected
overnight.

On Thu, 16 Mar 2017 20:22:42 +1100, you wrote:

>Hi all,
>
>I was recently asked to resurrect this interesting device by a colleague who 
>collects antique scientific instruments. It’s a "Chronoscope" made by the H. 
>Tinsley company in London in the early 20th century and used to measure time 
>intervals with the precision of those days. It's large and heavy in a polished 
>wooden case with a top deck that hinges up to reveal the innards. 
>
>The timing reference is a large tuning fork about 30 cm (1 foot) long and 
>running at 25 cps. It's normally in a glass fronted housing (removed for the 
>video) that includes a pair of hinged mechanical arms for starting it. It's 
>maintained in oscillation by an electromagnet and contact arrangement powered 
>from a 12V DC supply. The fork amplitude is controlled by a rheostat - too 
>much and the tines impact on the magnet. The video frame rate makes the fork 
>look slower than it actually is. I was able to extract a signal and measure 
>the frequency with a modern GPS disciplined counter - it's 0.007% off its 
>specified 25 Hz! The frequency is too low for my HP 5372A so I was not able to 
>easily get an idea of stability or do an ADEV measurement. The fork has quite 
>a high Q and takes over a minute to stop oscillating after the power is turned 
>off. There's a built in higher voltage AC power supply, probably a mains 
>transformer, potted in beeswax in a polished wooden box inside that is 
>intended t
 o
>  energise a large neon strobe lamp used to adjust the fork. Unfortunately the 
> lamp was not with the unit and is no doubt irreplaceable. 
>
>The 25 Hz signal is filtered by an LC network  and used to run a synchronous 
>motor in the Chronoscope unit. Synchronous motors not being self-starting, you 
>need to tweak a knob to get it going - there's a joke in there but I can't for 
>the life of me think what it could be ? The "Contact" switch and associated 
>socket on the back controls an electromagnetic clutch that connects the 
>clockwork counter mechanism to the motor and the contact "on" time is 
>indicated on the dials with 10 mS resolution. 
>
>There's not a single active device in there and after a clean and lube it runs 
>very nicely from a modern 12V DC plugpack. My friend is very pleased with it 
>and it will take pride of place in his collection. 
>
>I'd be interested to know if any time nuts have knowledge or experience of 
>this lovely instrument.
>
>A video of it is at  https://youtu.be/i5S8WS9iN_E
>
>Enjoy!
>
>Morris
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Re: [time-nuts] Antique precision timing device without electronics

[Mike Seguin]

Very interesting use of a tuning fork.

I have only seen this once before. I have the tuning fork used with an 
Ampex Model 300 reel to reel tape machine. The tuning fork was used as a 
reference in the power supply that drove the capstan motor for accurate 
speed.


It's 60 Hz not 25 Hz. It's marked B E Eisenhour. Patent is here:

https://www.google.com/patents/US1880923

Pic is here:

https://www.dropbox.com/s/opmxr521qqkx76r/60%20Hz%20Fork.jpg?dl=0

Mike

On 3/16/2017 2:04 PM, Bill Hawkins wrote:

Hi Morris,

If there's no active devices (and you'd be sure to see them, not solid
state) where does the power to operate the motor come from? Is it the
same contacts that drive the fork?

It's amazing that there is high Q when contacts must be operated by the
fork.

Did it come with instructions for setting the weights at the end of the
fork tines?

Best regards,
Bill Hawkins

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Morris
Odell
Sent: Thursday, March 16, 2017 4:23 AM
To: time-nuts@febo.com
Subject: [time-nuts] Antique precision timing device without electronics

Hi all,

I was recently asked to resurrect this interesting device by a colleague
who collects antique scientific instruments. It's a "Chronoscope" made
by the H. Tinsley company in London in the early 20th century and used
to measure time intervals with the precision of those days. It's large
and heavy in a polished wooden case with a top deck that hinges up to
reveal the innards.

The timing reference is a large tuning fork about 30 cm (1 foot) long
and running at 25 cps. It's normally in a glass fronted housing (removed
for the video) that includes a pair of hinged mechanical arms for
starting it. It's maintained in oscillation by an electromagnet and
contact arrangement powered from a 12V DC supply. The fork amplitude is
controlled by a rheostat - too much and the tines impact on the magnet.
The video frame rate makes the fork look slower than it actually is. I
was able to extract a signal and measure the frequency with a modern GPS
disciplined counter - it's 0.007% off its specified 25 Hz! The frequency
is too low for my HP 5372A so I was not able to easily get an idea of
stability or do an ADEV measurement. The fork has quite a high Q and
takes over a minute to stop oscillating after the power is turned off.
There's a built in higher voltage AC power supply, probably a mains
transformer, potted in beeswax in a polished wooden box inside that is
intended to
  energise a large neon strobe lamp used to adjust the fork.
Unfortunately the lamp was not with the unit and is no doubt
irreplaceable.

The 25 Hz signal is filtered by an LC network  and used to run a
synchronous motor in the Chronoscope unit. Synchronous motors not being
self-starting, you need to tweak a knob to get it going - there's a joke
in there but I can't for the life of me think what it could be ?? The
"Contact" switch and associated socket on the back controls an
electromagnetic clutch that connects the clockwork counter mechanism to
the motor and the contact "on" time is indicated on the dials with 10 mS
resolution.

There's not a single active device in there and after a clean and lube
it runs very nicely from a modern 12V DC plugpack. My friend is very
pleased with it and it will take pride of place in his collection.

I'd be interested to know if any time nuts have knowledge or experience
of this lovely instrument.

A video of it is at  https://youtu.be/i5S8WS9iN_E

Enjoy!

Morris

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--

73,
Mike, N1JEZ
"A closed mouth gathers no feet"
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[time-nuts] Vectron 233Y5317 OCXO data 250 Mhz

[Jeff AC0C]

Looking for a datasheet for this OCXO, or for the general family.  

Thanks!

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

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Re: [time-nuts] Smart Phone time display accuracy...?

[Paul]

On Thu, Mar 16, 2017 at 3:31 PM, Chris Albertson 
wrote:

> Again it would be fun to measure.  There is an API call to get the
> system time.  One could write a simple app to send this out
>

The iOS "Time" app/NTP client has been mentioned here before.  It displays
the offset between the device and NTP time at the instant of sync.  It
doesn't do that continuously though, you have force a new synchronization.
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Re: [time-nuts] Smart Phone time display accuracy...?

[Severin Haas]

The German PTB has a nice widget (https://uhr.ptb.de) to see the actual
time + deviation ("Abweichung"). Can not test this from another location
than UTC+1h, but probably it works at your location.
Does anybody of you know how they are measuring the time deviation? Some
JavaScript Voodoo?


Am 16.03.17 um 20:10 schrieb Nick Sayer via time-nuts:
> The time on mine is quite good, but I believe that’s because I have an Apple 
> watch. If you pair an iOS device to an Apple Watch, I believe it suddenly 
> “tries much harder” to keep its own clock in sync so that it can serve good 
> time sync to the watch.
> 
> Apple has made grandiose claims about the accuracy of the watch, but human 
> granularity for time is around 100 ms-ish anyway, so the bar is awfully high.
> 
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Re: [time-nuts] Smart Phone time display accuracy...?

[Wes]

My iPhone seems to be accurate to 5 minutes or so.  There are two of them in my 
house and they never agree.  My computer is saying 1:15 PM local time, my iPhone 
says 1:20PM


On 3/15/2017 7:32 PM, Mike Baker wrote:

Hello, Time-nutters--

Any thoughts on what the likely accuracy of smart phone time
displays might be?   I am thinking that the stacking of delays
along the path to its receive antenna plus any internal processing
delays would accumulate to some unknown degree.  Any
thoughts on this?

Mike Baker
*
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Re: [time-nuts] Smart Phone time display accuracy...?

[Jim Harman]

There are GPS apps for phones such as GPS Test Plus for Android that
display the time as received from the phone's GPS. I'm not sure if phones'
GPS modules produce a PPS output, but it would be cool if an app could send
a tick to the phone's speaker/headphones on the second.


> > Le 16 mars 2017 à 03:32, Mike Baker  a écrit :
> >
> > Hello, Time-nutters--
> >
> > Any thoughts on what the likely accuracy of smart phone time
> > displays might be?
>
> --

--Jim Harman
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[time-nuts] Antique precision timing device without electronics

[cdelect]

Very cool!

Thanks for sharing.

You could probably use any of the large vintage neon bulbs to replace the
missing lamp.

Cheers,

Corby

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Re: [time-nuts] Antique precision timing device without electronics

[Scott McGrath]

For the bulb you can probably replace it with a W1A or AR-1bulb which is an 
argon bulb commonly used in old school contact printers they have a purple hue 
and also emit long wave UV light   

I doubt if they are still manufactured but a photo shop or studio or chemist 
shop which developed film which has been in business a long time 60's and 70' 
is likely to have some as they were very common them

Content by Scott
Typos by Siri

> On Mar 16, 2017, at 5:22 AM, Morris Odell  wrote:
> 
> Hi all,
> 
> I was recently asked to resurrect this interesting device by a colleague who 
> collects antique scientific instruments. It’s a "Chronoscope" made by the H. 
> Tinsley company in London in the early 20th century and used to measure time 
> intervals with the precision of those days. It's large and heavy in a 
> polished wooden case with a top deck that hinges up to reveal the innards. 
> 
> The timing reference is a large tuning fork about 30 cm (1 foot) long and 
> running at 25 cps. It's normally in a glass fronted housing (removed for the 
> video) that includes a pair of hinged mechanical arms for starting it. It's 
> maintained in oscillation by an electromagnet and contact arrangement powered 
> from a 12V DC supply. The fork amplitude is controlled by a rheostat - too 
> much and the tines impact on the magnet. The video frame rate makes the fork 
> look slower than it actually is. I was able to extract a signal and measure 
> the frequency with a modern GPS disciplined counter - it's 0.007% off its 
> specified 25 Hz! The frequency is too low for my HP 5372A so I was not able 
> to easily get an idea of stability or do an ADEV measurement. The fork has 
> quite a high Q and takes over a minute to stop oscillating after the power is 
> turned off. There's a built in higher voltage AC power supply, probably a 
> mains transformer, potted in beeswax in a polished wooden box inside that is 
> intended 
 to
>  energise a large neon strobe lamp used to adjust the fork. Unfortunately the 
> lamp was not with the unit and is no doubt irreplaceable. 
> 
> The 25 Hz signal is filtered by an LC network  and used to run a synchronous 
> motor in the Chronoscope unit. Synchronous motors not being self-starting, 
> you need to tweak a knob to get it going - there's a joke in there but I 
> can't for the life of me think what it could be  The "Contact" switch and 
> associated socket on the back controls an electromagnetic clutch that 
> connects the clockwork counter mechanism to the motor and the contact "on" 
> time is indicated on the dials with 10 mS resolution. 
> 
> There's not a single active device in there and after a clean and lube it 
> runs very nicely from a modern 12V DC plugpack. My friend is very pleased 
> with it and it will take pride of place in his collection. 
> 
> I'd be interested to know if any time nuts have knowledge or experience of 
> this lovely instrument.
> 
> A video of it is at  https://youtu.be/i5S8WS9iN_E
> 
> Enjoy!
> 
> Morris
> 
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[time-nuts] Shout Out to N8UR in QST

[Randy Allen]

Congratulations on the nice article about John in the April issue of QST.

73, N4TVC, Randy


"..I set out to discover the inventions of God."  - John Muir




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Re: [time-nuts] Antique precision timing device without electronics

[Bill Hawkins]

Hi Morris,

If there's no active devices (and you'd be sure to see them, not solid
state) where does the power to operate the motor come from? Is it the
same contacts that drive the fork?

It's amazing that there is high Q when contacts must be operated by the
fork.

Did it come with instructions for setting the weights at the end of the
fork tines?

Best regards,
Bill Hawkins 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Morris
Odell
Sent: Thursday, March 16, 2017 4:23 AM
To: time-nuts@febo.com
Subject: [time-nuts] Antique precision timing device without electronics

Hi all,

I was recently asked to resurrect this interesting device by a colleague
who collects antique scientific instruments. It's a "Chronoscope" made
by the H. Tinsley company in London in the early 20th century and used
to measure time intervals with the precision of those days. It's large
and heavy in a polished wooden case with a top deck that hinges up to
reveal the innards. 

The timing reference is a large tuning fork about 30 cm (1 foot) long
and running at 25 cps. It's normally in a glass fronted housing (removed
for the video) that includes a pair of hinged mechanical arms for
starting it. It's maintained in oscillation by an electromagnet and
contact arrangement powered from a 12V DC supply. The fork amplitude is
controlled by a rheostat - too much and the tines impact on the magnet.
The video frame rate makes the fork look slower than it actually is. I
was able to extract a signal and measure the frequency with a modern GPS
disciplined counter - it's 0.007% off its specified 25 Hz! The frequency
is too low for my HP 5372A so I was not able to easily get an idea of
stability or do an ADEV measurement. The fork has quite a high Q and
takes over a minute to stop oscillating after the power is turned off.
There's a built in higher voltage AC power supply, probably a mains
transformer, potted in beeswax in a polished wooden box inside that is
intended to
  energise a large neon strobe lamp used to adjust the fork.
Unfortunately the lamp was not with the unit and is no doubt
irreplaceable. 

The 25 Hz signal is filtered by an LC network  and used to run a
synchronous motor in the Chronoscope unit. Synchronous motors not being
self-starting, you need to tweak a knob to get it going - there's a joke
in there but I can't for the life of me think what it could be ?? The
"Contact" switch and associated socket on the back controls an
electromagnetic clutch that connects the clockwork counter mechanism to
the motor and the contact "on" time is indicated on the dials with 10 mS
resolution. 

There's not a single active device in there and after a clean and lube
it runs very nicely from a modern 12V DC plugpack. My friend is very
pleased with it and it will take pride of place in his collection. 

I'd be interested to know if any time nuts have knowledge or experience
of this lovely instrument.

A video of it is at  https://youtu.be/i5S8WS9iN_E

Enjoy!

Morris

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Re: [time-nuts] Smart Phone time display accuracy...?

[Chris Albertson]

Apple Support claims "within 50 milliseconds of the definitive global
time standard".  At least that is what Apple gives in their spec.

It might use difference source depending on which radios are enabled.
The phone does have GPS and a cell network radio and both can be used
for time.But on a phone these radios are powered up and down as
needed.   I think best just to accept Apple's spec.

Again it would be fun to measure.  There is an API call to get the
system time.  One could write a simple app to send this out

Harder to know the specs on Android as there are so many manufactures
and versions and price points

On Thu, Mar 16, 2017 at 10:06 AM, Mike Garvey  wrote:
> CDMA mobile telephony needs system synchronization to +/- 10 uS in order to 
> smoothly handoff a moving client from one cell to the next. Most systems use 
> GPS to maintain this 10 uS.  This says nothing about how bad it could get 
> after that.
> Mike
>
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Baker
> Sent: Wednesday, March 15, 2017 22:33
> To: time-nuts@febo.com
> Subject: [time-nuts] Smart Phone time display accuracy...?
>
> Hello, Time-nutters--
>
> Any thoughts on what the likely accuracy of smart phone time
> displays might be?   I am thinking that the stacking of delays
> along the path to its receive antenna plus any internal processing delays 
> would accumulate to some unknown degree.  Any thoughts on this?
>
> Mike Baker
> *
> ___
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> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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>
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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Smart Phone time display accuracy...?

[Nick Sayer via time-nuts]

The time on mine is quite good, but I believe that’s because I have an Apple 
watch. If you pair an iOS device to an Apple Watch, I believe it suddenly 
“tries much harder” to keep its own clock in sync so that it can serve good 
time sync to the watch.

Apple has made grandiose claims about the accuracy of the watch, but human 
granularity for time is around 100 ms-ish anyway, so the bar is awfully high.

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Re: [time-nuts] Smart Phone time display accuracy...?

[Mike Cook]

Mine is a little over a second slow. Good enough for a date but not for any 
sort of nut.


> Le 16 mars 2017 à 03:32, Mike Baker  a écrit :
> 
> Hello, Time-nutters--
> 
> Any thoughts on what the likely accuracy of smart phone time
> displays might be?   I am thinking that the stacking of delays
> along the path to its receive antenna plus any internal processing
> delays would accumulate to some unknown degree.  Any
> thoughts on this?
> 
> Mike Baker
> *
> ___
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> and follow the instructions there.

"The power of accurate observation is commonly called cynicism by those who 
have not got it. »
George Bernard Shaw

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Re: [time-nuts] Smart Phone time display accuracy...?

[Chris Albertson]

It COULD be very good.   It would be easy for them to run NTP inside
the phone.   But I don't think they do as battery life is "everything"
  I think on IOS  they periodically run SNTP.

I just as interesting question is how to measure the phone's display?
 The biggest problem with all visual displays is the refresh rate.
Typically the screen is only updated at something like 60 Hz.  You
have to establish a network connection to be able to see higher
resolution time.Not hard to do as Android is running Linux inside
and iPhones a Unix derivative  You can


On Wed, Mar 15, 2017 at 7:32 PM, Mike Baker  wrote:
> Hello, Time-nutters--
>
> Any thoughts on what the likely accuracy of smart phone time
> displays might be?   I am thinking that the stacking of delays
> along the path to its receive antenna plus any internal processing
> delays would accumulate to some unknown degree.  Any
> thoughts on this?
>
> Mike Baker
> *
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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Smart Phone time display accuracy...?

[Mike Garvey]

CDMA mobile telephony needs system synchronization to +/- 10 uS in order to 
smoothly handoff a moving client from one cell to the next. Most systems use 
GPS to maintain this 10 uS.  This says nothing about how bad it could get after 
that.
Mike

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Baker
Sent: Wednesday, March 15, 2017 22:33
To: time-nuts@febo.com
Subject: [time-nuts] Smart Phone time display accuracy...?

Hello, Time-nutters--

Any thoughts on what the likely accuracy of smart phone time
displays might be?   I am thinking that the stacking of delays
along the path to its receive antenna plus any internal processing delays would 
accumulate to some unknown degree.  Any thoughts on this?

Mike Baker
*
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[time-nuts] Antique precision timing device without electronics

[Morris Odell]

Hi all,

I was recently asked to resurrect this interesting device by a colleague who 
collects antique scientific instruments. It’s a "Chronoscope" made by the H. 
Tinsley company in London in the early 20th century and used to measure time 
intervals with the precision of those days. It's large and heavy in a polished 
wooden case with a top deck that hinges up to reveal the innards. 

The timing reference is a large tuning fork about 30 cm (1 foot) long and 
running at 25 cps. It's normally in a glass fronted housing (removed for the 
video) that includes a pair of hinged mechanical arms for starting it. It's 
maintained in oscillation by an electromagnet and contact arrangement powered 
from a 12V DC supply. The fork amplitude is controlled by a rheostat - too much 
and the tines impact on the magnet. The video frame rate makes the fork look 
slower than it actually is. I was able to extract a signal and measure the 
frequency with a modern GPS disciplined counter - it's 0.007% off its specified 
25 Hz! The frequency is too low for my HP 5372A so I was not able to easily get 
an idea of stability or do an ADEV measurement. The fork has quite a high Q and 
takes over a minute to stop oscillating after the power is turned off. There's 
a built in higher voltage AC power supply, probably a mains transformer, potted 
in beeswax in a polished wooden box inside that is intended to
  energise a large neon strobe lamp used to adjust the fork. Unfortunately the 
lamp was not with the unit and is no doubt irreplaceable. 

The 25 Hz signal is filtered by an LC network  and used to run a synchronous 
motor in the Chronoscope unit. Synchronous motors not being self-starting, you 
need to tweak a knob to get it going - there's a joke in there but I can't for 
the life of me think what it could be  The "Contact" switch and associated 
socket on the back controls an electromagnetic clutch that connects the 
clockwork counter mechanism to the motor and the contact "on" time is indicated 
on the dials with 10 mS resolution. 

There's not a single active device in there and after a clean and lube it runs 
very nicely from a modern 12V DC plugpack. My friend is very pleased with it 
and it will take pride of place in his collection. 

I'd be interested to know if any time nuts have knowledge or experience of this 
lovely instrument.

A video of it is at  https://youtu.be/i5S8WS9iN_E

Enjoy!

Morris

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[time-nuts] Smart Phone time display accuracy...?

[Mike Baker]

Hello, Time-nutters--

Any thoughts on what the likely accuracy of smart phone time
displays might be?   I am thinking that the stacking of delays
along the path to its receive antenna plus any internal processing
delays would accumulate to some unknown degree.  Any
thoughts on this?

Mike Baker
*
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Re: [time-nuts] WTB: GPSDO

[Chris Albertson]

On Wed, Mar 15, 2017 at 1:09 AM, Attila Kinali  wrote:

> IMHO it's much easier to just
> get a known-good GPSDO and a rubidium for verification.

Yes, for sure it is easiest to buy something that already works.
But the question was how to bootstrap from scratch?  In other words,
if the only oscillator you own is one you built, how would you know
that it is working?


I actually did use your method.  I have a Rb and Thunderbolt, a pair
of freq. counters and so on.But still I wanted to see if I could
build from scratch and verify proper operation and keep the budget
under say $50 for everything from antenna to power cord. I think
it can be done but one can only verify longer term stability.

(Yes you were correct a GOOD oversized XO is not sensitive to the
environment.  But notice the above budget.)

-- 

Chris Albertson
Redondo Beach, California
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