[time-nuts] Arduino clock with NTP Input and analog meter outputs
MITCHELL JANOFF
majanoff at verizon.net
Sun Feb 24 17:21:14 UTC 2019
I’ve designed and built an Arduino based clock that receives the time from an NTP server, converts the time to voltages, and outputs the voltages to analog volt or ammeters using the PWM pins on the Arduino. The clock displays hours, minutes and seconds, each on a separate analog meters with customized clock faces. The design, code, and clock faces, and a picture of the clock are in the public domain, and I’ve posted all the information required to build this clock in a GitHub folder (www.github.com/majanoff). The clock faces are in PDF format (for Weston 301 panel meters) that can be printed and glued onto the meter metal faces. If you are interested in building the clock, I can create custom faces based on your meters or there is a link in the folder pointing to the meter face software. I’ve also built the same clock using time from a GPS receiver and a DS1307 real time clock module (posted on GitHub) in-place of the NTP internet connection. I used lookup tables for the output voltages for each of the meters, as there is a bit of non-linearity in the output, which can be corrected via the lookup tables.
Please contact me directly if you are interested in more information.
Mitch.
Kc2mfb
--------------------------------------------
On Sun, 2/24/19, <time-nuts-request at lists.febo.com> wrote:
Subject: time-nuts Digest, Vol 175, Issue 33
To: time-nuts at lists.febo.com
Date: Sunday, February 24, 2019, 12:00 PM
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Today's Topics:
1. Re: Bricked Garmin GPS 18x
LVC (Hal Murray)
2. Re: Clock project request
from IEEE (John Reid)
3. Re: HP Stories: An
architectural view of the HP 5060/5061 and
awkward oscillator
adjustments. (Rice, Hugh (IPH Writing Systems))
----------------------------------------------------------------------
Message: 1
Date: Sat, 23 Feb 2019 14:23:34 -0800
From: Hal Murray <hmurray at megapathdsl.net>
To: Discussion of precise time and
frequency measurement
<time-nuts at lists.febo.com>
Cc: hmurray at megapathdsl.net
Subject: Re: [time-nuts] Bricked Garmin
GPS 18x LVC
Message-ID:
<20190223222334.2405D40605C at ip-64-139-1-69.sjc.megapath.net>
Content-Type: text/plain;
charset=us-ascii
> If you open it up, then simply
connect a load resistor, perhaps in the
> neighborhood of 100 ohms (but
definitely not a direct short!) across the
> super cap to drain it faster.
I couldn't open mine up.
I got one into a useless state. I
don't know how I did it, but it wasn't
updating firmware. Mine recovered
after a while, but I don't know how long it
took. I tossed it on the junk
pile because it was useless. Eventually, I
tried again and it worked.
Note that trying too soon probably
charges up the super cap and thus restarts
the clock.
--
These are my opinions. I hate
spam.
------------------------------
Message: 2
Date: Sun, 24 Feb 2019 11:51:13 +0000
From: John Reid <reid.john at hotmail.com>
To: "time-nuts at lists.febo.com"
<time-nuts at lists.febo.com>
Subject: Re: [time-nuts] Clock project
request from IEEE
Message-ID:
<CY4PR13MB1208932C9CAD0F2492D7684FF8790 at CY4PR13MB1208.namprd13.prod.outlook.com>
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charset="utf-8"
I would love something that gave a list
of options set from the location in the NMEA string.
Such as this time zone or different,
with nearby zones first; DST on/off. Could get to be a
significant effort very quickly, but maybe there are xml
files out there that would make it easy?
John
On 24/2/19 4:00 am, time-nuts-request at lists.febo.com<mailto:time-nuts-request at lists.febo.com>
wrote:
Message: 4
Date: Sat, 23 Feb 2019 15:47:11 +0100
From: Magnus Danielson <magnus at rubidium.se><mailto:magnus at rubidium.se>
To: time-nuts at lists.febo.com<mailto:time-nuts at lists.febo.com>,
Glenn Zorpette <g.zorpette at ieee.org><mailto:g.zorpette at ieee.org>
Subject: Re: [time-nuts] Clock project
request from IEEE
Message-ID: <4d54789a-e3eb-46f6-0d0d-523954c419fb at rubidium.se><mailto:4d54789a-e3eb-46f6-0d0d-523954c419fb at rubidium.se>
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Hi,
On 2019-02-22 19:31, Tom Van Baak
wrote:
I received the following email and
permission to post it on time-nuts:
Hello,
I am the executive editor of the IEEE's
flagship magazine, IEEE Spectrum.
I recently acquired a TAPR "Pulse
Puppy" and I am intrigued by the idea of
using it to build a very precise clock
that I would share with Spectrum's readers.
I would like to partner with an
engineer with experience in digital clocks, who
would be credited as co-author on this
project.
Can you suggest someone who might be
interested in this project? I would be
much obliged if you had some
suggestions.
Kind regards,
-Glenn
Glenn's contact info is:
Glenn Zorpette
g.zorpette at ieee.org<mailto:g.zorpette at ieee.org>
You can just imagine all the many ways
the project could head. Send Glenn a note if you want to
help. Or post here if you have suggestions.
I think we should contribute with our
wealth of knowledge.
There is several aspects that would
form a digital clock. Many of the
pieces is readily available, but we
rarely put them together in a system.
The TAPR Pulse Puppy is a nice little
thing. I don't have one myself,
but I can see how it could be useful,
so thanks for making it aware of it.
The Pulse Puppy obviously solves two
things, one having a crystal
oscillator and output a divided down
signal.
To build a clock system we should
consider from where we get the time,
and how we maintain it. These days the
answer will be a GPS module which
output it's time in serial form, such
as the NMEA output format. That
will give us the date and time of day
that the PPS output represents, in
UTC, and then the PPS pulse would give
us the phase. The upside of this
is that we get the date and time, but
we don't get it adjusted to our
local time-zone, we also depends
strictly on the presence of the GPS
signal. Also, the PPS pulse varies due
to GPS properties as well as the
clock-pulse assignment causing the
sawtooth error.
As widely known in the group, sawtooth
error corrections is available
over the serial interface from several
receivers. Further, to make a
more quiet source you want to filter
out some of the GPS noise. This is
where the Pulse Puppy can come at
handy, as you can steer the oscillator
with the GPS PPS pulse and sawtooth
corrections, measure the
time-difference and then create a
servo-loop to steer the oscillators
frequency and phase to an average of
that from the GPS. The produced PPS
pulse can be made more quiet for the
short term stability while
following the GPS long-term. In that
regard we can filter and get a more
stable clock.
Another drawback may be that we loose
GPS signal. There are many
possible sources for that, but
regardless which source, one needs to
cover up the loss. This you do with
hold-over, which is the secondary
function of an oscillator. During
hold-over the steering of the
oscillator should be such that it
minimize the time-error of a properly
operating time and that of the clock in
the oscillator. This is in it's
most trivial form achieved by ensuring
that the frequency steering of
the oscillator is maintained as if it
was locked to the GPS. The
hold-over properties to a high degree
depends on how well the oscillator
is steered, and how stable the
oscillator is to start with, but it ends
being a material sport in that you go
from TCXO, small OCXO, bigger
OCXO, double-oven OCXO, rubidium clock,
cesium clock etc. The GPS module
has a small TCXO, but for these
purposes you probably want to have
something better.
The digital clock part would at first
look very trivial, it has a simple
clock counter that counts 24 hours, 60
minutes and 60 seconds. OK, so we
need to set this clock. Oh, we might
have time-zones. Oh, we might have
shifts to and from daylight savings.
Oh, we might have leap-seconds.
Already there we have a little bit of
added complexity. Nothing that
can't be handled thought.
Also, we want to set the time from the
GPS module, so that would require
us to have a serial link just to get
the NMEA data or similar at least.
We probably want to get additional data
to be warned about leap-seconds,
get the UTC-GPS offset, GPS week number
etc. A separate serial link
would probably be useful to set
time-zone data or set the time from
another source, such as a computer
timed with NTP.
It may also be interesting to encode
time to be sent out. Serial
interface, IRIG-B or similar.
Now, as we look at this, we cover quite
a bit, and you can go into
depths to do this better, as needed in
professional needs. However, I
also see a potential to teach several
different concepts that comes
together in a DIY project, which also
may be very handy.
If done with a little bit of care, we
can teach proper terms to be
scientific and educational in one end,
while also being very hands on
and useful in the other.
At the same time we can "crash" into
some of the challenges that the
professional world sees, and also lots
of people needs to be educated in
too. Being hands on and simplified just
makes it more concrete, rather
than abstracts concepts. Could be very
useful and educational for a wide
audience.
Once bitten by the time-nuts bug, there
is many things to improve.
Cheers,
Magnus - both hobbyist and
professional
------------------------------
Message: 3
Date: Sun, 24 Feb 2019 12:02:47 +0000
From: "Rice, Hugh (IPH Writing
Systems)" <hugh.rice at hp.com>
To: Discussion of precise time and
frequency measurement
<time-nuts at lists.febo.com>
Subject: Re: [time-nuts] HP Stories: An
architectural view of the HP
5060/5061 and
awkward oscillator adjustments.
Message-ID:
<CS1PR8401MB10789EE2AC1462203AFD86ED8C790 at CS1PR8401MB1078.NAMPRD84.PROD.OUTLOOK.COM>
Content-Type: text/plain;
charset=WINDOWS-1252
Several people have asked about the Len
Cutler ban on Aluminum Electrolytic Capacitors in HP
Frequency Standards. Rick Karlquist could shed more
light on this too. The legend of the ban was passed
along to me, perhaps by Lou Mueller, who liked to tell
stories of the old days. In 1985, we were not taking
the ban literally. For example, the 2400uF main power
supply filter capacitor was AL-Electrolytic, as were a few
other smaller capacitors on the power regulator. I
sidestepped the capacitor issues on my simple battery
charger by not having a filter cap after the
transformer/full-wave-bridge, and just used 120 Hz pulses,
since the battery didn't care about DC vs. pulsed DC.
(I thought it was pretty clever to leave out the main filter
cap.) Where possible, Tantalum capacitors were
used. For the few places where AL caps were
used, they were heavily de-rated, operating at 50% of rated
voltage for example.
As one reader pointed out, back in the
1965 when the 5060A was developed, AL-Electrolytic caps were
likely a lot less reliable than in 1985 when I worked on the
5061B.
From: time-nuts <time-nuts-bounces at lists.febo.com>
On Behalf Of Rice, Hugh (IPH Writing Systems)
Sent: Saturday, February 23, 2019 8:49
PM
To: time-nuts at lists.febo.com
Subject: [time-nuts] HP Stories: An
architectural view of the HP 5060/5061 and awkward
oscillator adjustments.
Hello Time-Nuts,
.... Stuff deleted .....
It was fantastically reliable. Only
linear power circuits, with robust heat sinking of all power
devices. The legendary Len Cutler ban on aluminum
electrolytic capacitors. 5060s were still in use in 1985,
after 20 years of constant operation. Likewise, 5061As were
abundant in time standards for 25+ years until they were
replaced by the 5071A in the 1990s.
------------------------------
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