[time-nuts] FA2 internal OCXO warm-up time

[Mark Sims]

I did a test of the FA2 internal OCXO warm up time.  I powered mine down for 4 
fours and then powered it up and measured the frequency as it warmed up.  It 
looks like it takes 45 minutes to stabilize.  

Note that it took a week of constant power for the oscillator drift rate to 
settle down.  The drift on mine seems to be around 0.00025 Hz/day.  I need to 
do a longer test to better weed out temperature sensitivity.

BG7TBL internal oscillator warm up time:

Minutes   Freq error
0 221 Hz
1 17 HZ
2 0.2760 Hz
3 0.0500 Hz
4 0.0350 Hz
5 0.0240 Hz
100.0130 Hz
150.0080 Hz
200.0060 Hz
250.0050 Hz
300.0042 Hz
350.0040 Hz
400.0034 Hz
450.0021 Hz <--- stable
500.0025 Hz
550.0022 Hz
600.0020 Hz

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[time-nuts] DC distribution

[Bill Dailey]

Setting up a new workbench and am wondering what wisdom people can offer.  I am 
powering numerous synthesizers (5v), small receivers (5v), Upconverters (5v), 
larger receivers (12v), fury Gpsdo’s.. etc.   anyone use something neat and not 
real expensive for distributing 5v and 12v.  I am hoping for a long COTS pcb 
with fusing and maybe holes for plugs.  

Any insights?

Bill

Bill Dailey

Negativity always wins the short game. But positivity wins the long game. - 
Gary Vaynerchuk

Don’t be easy to understand, 
Be impossible to misunderstand 
- Steve Sims
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[time-nuts] FA2 Programming

[Mark Sims]

The command $Cxx* will set the contrast.  xx can be 00 to 63.  Ignore the 
measurement data that the FA2 sends continuously and just type over it (or 
disconnect the input signal).   It should respond with something like CONTCOK 
if the command is accepted.  Note that the value is stored in EEPROM and there 
is no way to read back the current setting.

Note that the FA2 (rather weirdly) uses the '*' character as the end-of-line 
character when sending commands instead of the much more rational carriage 
return key...  perhaps China has a shortage of  keystrokes ;-)

I am currently adding the various FA2 config commands to Lady Heather.

---

>I am able to connect using USB and tried Putty in serial mode. When I connect 
the port, the FA2 dutifully starts outputting the measured frequency but that's 
the extent of my control, or lack thereof.  Has anyone more skilled than I done 
any programming?

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[time-nuts] FA2 Programming

[Wes]

I finally got my FA2 yesterday.  Seems to work fine, except for one thing (so 
far) the screen is blinding and viewable from only straight on.  I'm afraid it 
won't last long in this state. According to the manual there is a programmable 
adjustment for contrast but my programing skills ended with writing instrument 
control software in HP Basic in the 1980s.


I am able to connect using USB and tried Putty in serial mode. When I connect 
the port, the FA2 dutifully starts outputting the measured frequency but that's 
the extent of my control, or lack thereof.  Has anyone more skilled than I done 
any programming?


Wes  N7WS


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Re: [time-nuts] Talking Clock

[John Reid]

> I believe an original talking clock is being maintained in the 
> Telecommunications Museum in Hawthorn (Australia). Third floor, 
> Hawthorn Telephone Exchange.
>
>
> John
>
>
>> --
>>
>> Message: 1
>> Date: Tue, 1 Oct 2019 02:58:45 -0700
>> From: "D. Resor" 
>> To: "'Discussion of precise time and frequency measurement'"
>> 
>> Subject: Re: [time-nuts] Talking Clock
>> Message-ID:
>> 
>> 
>>  
>>
>>
>> Content-Type: text/plain;    charset="us-ascii"
>>
>> I believe this is the glass plate MkII Talking Clock which referred 
>> to in
>> AUS.  It was retired in 1990.  Also shown is the digital replacement 
>> system.
>>
>> Progress is great, but in some ways it's also kind of sad.
>>
>> The speaking Clock pt1, Talking Clock
>> https://youtu.be/fp4zlMZVcmM
>>
>> The Speaking Clock pt 2, Talking clock
>> https://youtu.be/9LVzKHOodC4
>>
>>
>> Donald Resor
>> N6KAW
>>
>>
>>
>> -Original Message-
>> From: time-nuts  On Behalf Of
>> vilgot...@gmail.com
>> Sent: Monday, September 30, 2019 9:50 PM
>> To: time-nuts@lists.febo.com
>> Subject: Re: [time-nuts] Talking Clock
>>
>> The electro-mechanical-optical clock was made obsolete years ago and the
>> voice is now generated electronically. I think the reason it's being 
>> closed
>> down is that the PSTN is digital and so delays are unpredictable 
>> leading to
>> possible errors in the time. According to a news item I saw the 
>> company that
>> runs the clock and supplies the audio wants to keep it going but the
>> national network supplier (Telstra) is determined to close it down 
>> because
>> of "network incompatibility".
>>
>> I made a talking clock with that format a few years ago. It is based 
>> on an
>> AVR processor that uses the mains frequency as a reference. The voice is
>> generated by an ancient speech synthesizer chip that sounds like Stephen
>> Hawking and the time is simultaneously displayed on a VFD. A PIR 
>> detector
>> switches off the outputs when there's no human around. It can be seen at
>> https://www.youtube.com/watch?v=lmg0YsHlB3g&t=3s
>>
>> It wouldn't be hard to use the same platform to translate the time 
>> from a
>> GPS receiver into the spoken and visual word.
>>
>> Morris
>>
>>
>>
>> -Original Message-
>>
>> --
>>
>> Date: Tue, 1 Oct 2019 08:00:25 +1000
>> From: Neville Michie 
>> To: Discussion of precise time and frequency measurement
>> 
>> Cc: Neville Michie 
>> Subject: [time-nuts] Talking Clock
>>
>>
>> Here in Australia we are suffering the loss of one of the significant
>> developments in accurate time keeping and dissemination.
>> The talking clock, built in England, with sound tracks on rotating glass
>> disks, has been on the Australian telephone system for more than half a
>> century.
>> The system was timed by quartz oscillators, synchronised to the local
>> observatory time.
>> Now in spite of the trivial cost of maintaining the system it has been
>> removed by the money-hungry telco which took over the government run
>> telephone system.
>> Now it occurs to me that the sound tracks occupy a very small digital 
>> space,
>> and with modern flash drives and a little logic the talking clock 
>> could be
>> driven by any time nut's disciplined time source.
>> So is there a time nut who could design a voice output that we could all
>> use?
>>
>> ?At the third stroke the time will be??
>>
>> cheers,
>> Neville Michie
>>
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Re: [time-nuts] Timebase Replacement - Seiko Epson RTC-72421

[Robert LaJeunesse]

Looking at the datasheet I'd expect finding a drop-in replacement is likely 
problematic. A rather involved RTC module providing seconds out to 100 years. 
(Although it looks a lot like a Seiko RTC chip I used in the late 70s.)  
Emulation would probably require an FPGA approach, or one using a 2-port 
memory, either driven from a more stable clock that, ideally, is GPS 
disciplined. But a full emulation is an involved design, and all you really 
need to do is sync the seconds, so what's simpler?

One possible approach is to try to do a "jam" correction on the fly. With a 
little study on how the module interacts with the rest of the carillon there is 
likely dead time when another controller can take over access to the RTC 
module. Read the seconds, compare to UTC (or GPS) seconds, adjust if needed by 
blipping the 30 second adjust bit (D3 in register CD, see full datasheet link 
below). If GPS is not present, do nothing, assuming GPS will come back before 
the RTC module skews a full 30 seconds. Depending on how the STD.P pin is used 
there may be no need for read access, as it may provide pulse per second or 
minute that could be used for comparison against GPS. In any case register 
access would require an intercept board that multiplexes all the control lines 
such that your added controller can get to the necessary registers. Unless I'm 
wrong (always a possibility) there is no need to access most of the registers 
in the part, simplifying the design. 

Or maybe the chip core matches that external crystal RTC I used years ago 
(sorry, don't remember the Seiko part number offhand). You could then build a 
module replacement without jam logic but with a GPS disciplined 32.768kHz 
oscillator. That would be a much simpler approach for minimal drift.  

Bob LaJeunesse

Found a full datasheet at 
https://www.manualslib.com/download/47987/Epson-Rtc-72421-A.html
 

> Sent: Thursday, October 03, 2019 at 1:00 AM
> From: "Corey Sukalich" 
> To: time-nuts@lists.febo.com
> Subject: [time-nuts] Timebase Replacement - Seiko Epson RTC-72421
>
> Hi all,
> 
> New to the list, but have known of its existence for a while as I know others 
> that have been subscribers.
> 
> My question pertains to a timebase used in a Schulmerich carillon bell tower 
> system from the 1990’s.
> 
> The Seiko Epson RTC-72421 Real Time Clock Module (4-bit) is used, but the 
> clock ends up walking to a noticeable degree (minutes) over a period of 
> months.  Is this expected for the device in question, or could it possibly 
> have a defect?
> 
> Datasheet available here:
> https://support.epson.biz/td/api/doc_check.php?dl=brief_RTC-72421&lang=en 
>   
> 
> From what I can tell it uses an internal oscillator, so it sounds like I 
> would need to find a drop-in replacement or build a module that will replace 
> it with a significantly better time standard.  Any advice is appreciated as 
> to whether could be accomplished without too much trouble.  I’ve repaired a 
> few of these systems over time and there are enough of them still in the wild 
> that it might be worth me fabricating a module for them.
> 
> Also, on the off chance someone is versed in EPROM data recovery or knows of 
> a resource for it, I would appreciate that information as well.
> 
> Regards,
> Corey
> N9WIV
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Re: [time-nuts] Timebase Replacement - Seiko Epson RTC-72421

[paul swed]

Corey welcome to the group.
As i recall those clocks absolutely drifted like that.
Regards
Paul.

On Thu, Oct 3, 2019 at 1:02 AM Corey Sukalich  wrote:

> Hi all,
>
> New to the list, but have known of its existence for a while as I know
> others that have been subscribers.
>
> My question pertains to a timebase used in a Schulmerich carillon bell
> tower system from the 1990’s.
>
> The Seiko Epson RTC-72421 Real Time Clock Module (4-bit) is used, but the
> clock ends up walking to a noticeable degree (minutes) over a period of
> months.  Is this expected for the device in question, or could it possibly
> have a defect?
>
> Datasheet available here:
> https://support.epson.biz/td/api/doc_check.php?dl=brief_RTC-72421&lang=en
> 
>
>
> From what I can tell it uses an internal oscillator, so it sounds like I
> would need to find a drop-in replacement or build a module that will
> replace it with a significantly better time standard.  Any advice is
> appreciated as to whether could be accomplished without too much trouble.
> I’ve repaired a few of these systems over time and there are enough of them
> still in the wild that it might be worth me fabricating a module for them.
>
> Also, on the off chance someone is versed in EPROM data recovery or knows
> of a resource for it, I would appreciate that information as well.
>
> Regards,
> Corey
> N9WIV
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Re: [time-nuts] Timebase Replacement - Seiko Epson RTC-72421

[Gregory Beat via time-nuts]

Corey -
These Seiko Epson RTC chips can and do fail (oscillator failure or moves “out 
of spec”).
These chips have a rough accuracy of ~ 1 second/day.  
That level of accuracy can produce ~ 365 seconds/year (6 minutes)

Your question suggests that you are searching for a Clock with a higher 
frequency accuracy/stability — than this 1990s RTC solution provides (10-6).  

Seiko Epson RTC-72241 RTC - Full Datasheet
http://www.s100computers.com/My%20System%20Pages/PIC&RTC%20Board/Epson%2072421%20manual.pdf

Page 20 of the full datasheet provides insight & finding the frequency 
stability (time).

1.) Frequency and temperature characteristics can be approximated 
using the following equations.
** Finding the Frequency Stability **
∆fT= α ( θT- θX)2

∆fT   : Frequency deviation in any temperature
α (1/°C2) : Coefficient of secondary temperature ( −0.035±0.005 ) × 10-6 / °C2
θT ( °C )  : Ultimate temperature (+25±5 °C)
θX ( °C )  : Any temperature

2.) To determine overall clock accuracy, 
add the frequency precision and voltage characteristics.
∆f/f= ∆f/fo+ ∆fT+ ∆fV

∆f/f   : Clock accuracy (stable frequency) in any temperature and voltage.
∆f/fo : Frequency precision
∆fT   : Frequency deviation in any temperature.
∆fV   : Frequency deviation in any voltage.

3.) How to find the date difference
Date Difference = ∆f/f × 86400(s)
** For example: ∆f/f = 11.574 × 10-6 is an error of approximately 1 second/day. 
**
—
Greg
==

Date: Thu, 3 Oct 2019 00:00:44 -0500
From: Corey Sukalich 
To: time-nuts@lists.febo.com
Subject: [time-nuts] Timebase Replacement - Seiko Epson RTC-72421

My question pertains to a timebase used in a Schulmerich carillon bell tower 
system from the 1990’s.

The Seiko Epson RTC-72421 Real Time Clock Module (4-bit) is used, but the clock 
ends up walking to a noticeable degree (minutes) over a period of months.  Is 
this expected for the device in question, or could it possibly have a defect?

Corey
N9WIV

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Re: [time-nuts] Timebase Replacement - Seiko Epson RTC-72421

[Chris Caudle]

On Thu, October 3, 2019 12:00 am, Corey Sukalich wrote:
> My question pertains to a timebase used in a Schulmerich carillon bell
> tower system from the 1990’s.
>
> The Seiko Epson RTC-72421 Real Time Clock Module (4-bit) is used, but the
> clock ends up walking to a noticeable degree (minutes) over a period of
> months.  Is this expected for the device in question, or could it possibly
> have a defect?

The datasheet you linked shows 5ppm max aging in the first year, but no
aging curves after the first year.
Using the worst case value just for a rough estimate, mid-90's would mean
some devices could be 25 years old:
5ppm * 25 yrs -> 125ppm off nominal
Note that  nominal starts at anywhere from +/-10 to +/- 50 ppm depending
on what model  you have, and aging could be in the same direction as
initial offset, opposite direction as  initial offset, or could change
direction at some point during the device lifetime.

Given all those caveats, 125/1,000,000 * 30 days/month * 24hrs/day *
60min/hour -> 5.4 min/month

So if the clocks are losing or gaining anything less than 5 minutes per
month, then I would say they are probably beating the worst case value
guaranteed in the datasheet.

> From what I can tell it uses an internal oscillator, so it sounds like I
> would need to find a drop-in replacement or build a module that will
> replace it with a significantly better time standard.

Or build an interface which will push in the correct time at some time
that is unlikely to be noticed (e.g. 2:42AM,  some time not right on an
hour or  half hour).

> Also, on the off chance someone is versed in EPROM data recovery or knows
> of a resource for it, I would appreciate that information as well.

There are a lot of devices which can read data from an  EEPROM, that
aspect will be nearly trivial, the trouble is usually interpreting the raw
data, or filling in any data which has degraded over time and can no
longer be read.

-- 
Chris Caudle



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Re: [time-nuts] FA2

[shouldbe q931]

On Thu, Oct 3, 2019 at 12:07 AM Didier Juges  wrote:

> Raspberry Pi has no display, no keyboard.

Yes, the Pi does not have a display or a keyboard, but it does have  USB,
GPIO, Bluetooth WiFi and Ethernet, and separate power.


> If you add those, you far exceed
> the cost of a 7" tablet

Does a device for logging data need a display or a keyboard ?


> and you still have a pile of stuff that barely fits
> in a shoe box let alone in a decent looking enclosure

Without the screen and keyboard you get a _much_ smaller device.


> and that you would
> not want to leave on a table unattended.
> A cheap Android tablet is hard to beat if you need a display and keyboard
> and having played quite a bit with both, my RPis are still all in the same
> box where they came in while a number of Android tablets are used
> throughout the house as remote controls for a number of things.
> The most recent is a$49 7" Fire tablet to use also as a controller. Nice
> piece of hardware for the cost.
>
As something to control other things, an Android tablet (or phone with
WiFi) is very good, I also have several, but for datalogging (temperature,
humidity, ADS-B etc), or for providing network access to a device that has
serial or USB management interfaces, I use an rPi without screen or
keyboard, all bar one have have never had a screen or keyboard connected to
them.

People have a tendancy to pick up tablets, when a single USB (mini/micro/C)
cable is used for data collection as well as power, I would be concerned
that the cable might be unplugged, with something like a rPi, there is no
requirement to move the rPi, but one could certainly use a tablet to access
the data that has been logged.

Different horses for different courses (-:


> Writing Android apps using a tool like B4A is a lot of fun, with a Visual
> Studio like environment.
>
> Of course, if you need a lot of discrete IOs, the RPi is very handy.
>
> Didier KO4BB
>
> On Wed, Oct 2, 2019, 12:00 PM shouldbe q931 
> wrote:
>
> > On Wed, Oct 2, 2019 at 4:00 PM ew via time-nuts <
> time-nuts@lists.febo.com>
> > wrote:
> >
> > > Good Morning DidierThank you for your response. The "ONLY" thing we
> would
> > > like to do is record and display the info coming out of the RS post. To
> > day
> > > making long term observations ties up a PC or Laptop with fans and a
> > > HP53132. Gone for a week the main concern is fan failure. Store the
> info
> > on
> > > the Tablet in a SD chip or in it and when ready download through the
> USB
> > > port that we use for importing data to a memory stick for further
> > processing
> > >
> > 
> >
> > Rather than a tablet, might I be so bold as suggesting using a fanless
> PC,
> > such as a RaspberryPi (other small fanless computers are available).
>
> Cheers

Arne
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