Erik,
Just a thought. The 7805 in your schematic appears to be a big part of
the signal chain. I've run into issues with 78xx series regulators being
noisy. Spent a few weeks chasing down noise issues in some equipment and
the 78xx regulator was a part of the problem. Replaced it with LT3042
Rick,
Very delayed response...
So, your thought/comment about tempco stuck in the back of my head. This
little board has progressed to the point where it can measure it's own
RTCC oscillator against and external 10Mhz ref.
Out of curiosity a very simple oven was slapped together (Leftover
Hi,
Have you looked at the delay of the GPS signal passing through the
filter to the one unit vs C on the other?
I've seen a similar situation where a bias T was the culprit. I don't
recall the numbers off hand but it was significant enough to notice, and
the difference went away once the T
On 4/14/2022 3:30 AM, time-nuts-requ...@lists.febo.com wrote:
I wouldn't go as far as saying that we KNOW EXACTLY how to reduce 1/f
noise or all the other unwanted side effects (RTN, leakage currents, you
name it). We do observe however, that in many cases these effect are
somewhat
After playing with cap values the crystal is running about 6.5ppm fast.
Plenty good for what it is. Of course this was with a sample size of 1.
Being a time-nut, I did try a few different cap values just to see if it
could be made any better. The Next closest cap combo gives 8.3ppm slow.
All,
Ahhh, Yes. Checking notes, during the initial build I slapped a pair of
10pF caps down (all I had on hand) just to get the RTCC oscillators
somewhat working. I can see now that is WAY under needed capacitance.
Measurements are taken right in the micro, so no external leads to
influence
Hi,
I've got a 32.768Khz (USA number format) crystal on a RTCC oscillator of
a small micro, and it's running fast. Around 10 seconds per day or so.
This is a bit more than an order of magnitude more than the datasheet
states.
The 9 seconds per day error should be a good measurement. The
I'd really like to see how these perform.
https://www.u-blox.com/en/product/lea-f9t-module
https://www.u-blox.com/en/product/zed-f9t-module
However, getting them in hand is sometimes difficult. That may be
changing since the last time I've really looked...
Dan
On 2/15/2022 3:30 AM,
Hi,
Perhaps my post was misleading. The pendulum quality isn't particularly
tied to the machine accuracy. AFIK, the material selection and heat
treatment (and many other things) are much more important than
dimensional accuracy for a pendulum itself. Any pendulum should have
adjustments to
Hi All,
This is maybe an odd request for this list, so I'll keep it short.
A pendulum project has me pushing the limits of my current lathe. So I'm
staring to shop around for a higher end tool room type precision lathe.
Hardinge HLV-H, Monarch 10EE, etc.
If by chance anyone has a lathe that
Hi,
So, that finger of signal appearing above the north pole shows up even
after the GPS survey is done. Any ideas on how to figure out what's
causing that?
My first thought is to try look at it with a different model of GPS unit.
Is it possible it could be a signal reflection in the cable
All, a few replies at once...
I seemed to remember higher elevation masks than have been recommended,
in the 20 or 30 degree range. However the comments seem to be quite low,
7 to 10 to start with.
Dana,
Trying multiple masks is certainly a good idea. I don't really have
another good
Or Better yet... Time-lapse!
Preferably, timestamped.
On 9/10/2021 3:30 AM, time-nuts-requ...@lists.febo.com wrote:
Message: 15
Date: Thu, 9 Sep 2021 18:03:08 -0500
From: "Graham / KE9H"
Subject: [time-nuts] Re: in-ground clock room
To: Discussion of precise time and frequency measurement
Hi,
Has anyone else here had trouble with any of the LaCrosse UltrAtomic
clocks?
I personally purchased one new around early 2017 it worked well until
early this summer. At that point it suffered a mechanical failure where
the minute hand would just swing around the 6 'o clock mark.
Dana,
Just curious, can you share some details on what you are using for the
IQ demodulator? Is this a 'roll your own' solution Gilbert cell mixer, etc?
Thanks,
Dan
On 8/23/2021 3:30 AM, time-nuts-requ...@lists.febo.com wrote:
Message: 4
Date: Sun, 22 Aug 2021 10:16:56 -0500
From: Dana
Hi All,
Just to be clear, I am not the person who made the crystals glow blue. I
just noticed some pictures of that happening on the auction site:
https://www.ebay.com/itm/8x-Quartz-Resonator-1000-kHz-Crystal-oscillator-gold-Sonoluminescence-effect-NOS/113862454353
Hi All,
Many thanks to all who replied. I've beep picking my way through the
suggestion, videos, and other information.
The next steps will be to try to measure some of the crystal parameters
with the stuff I have laying around the lab. The supplied information
will keep me working on this
Hi Hal,
I won't argue there may be things to consider going down this path.
However, for a device such as Andy's that (as I understand) currently
has no data logging this would be a very cheap ($4.29 ebay clone, $5.23
16Gb Sandisk MicroSD) and easy option. Set it and forget it.
One could
Andy,
Perhaps one of the little openlog units from sparkfun, or one of the
clones would work for logging?
https://www.sparkfun.com/products/13712
Honestly, I have two and a pair of 32Gb Cards, but have not tried them
yet. Seems like a good solution for a project like this. I don't know
how
Hi,
For some appliances however, I question if a clock display is really
needed. A toaster certainly wouldn't need anything more than an RC. A
couple of percent error on how long I warm up lunch probably won't matter!
However, some appliances and consumer grade equipment do utilize RC
Dana,
Just an FYI. Apparently, there are knockoff clone copies of the TinySA
out there. (Yes, making a knockoff clone of a $50 spectrum analyzer is a
thing, go figure!)
Apparently, these have substandard performance, and a host of
issues/concerns. I ran into this on the TinySA web site.
Hi,
Darn, Bob beat me to it! I was going to suggest the AD590 and a suitable
ADC. The ceramic part is relatively small.
https://www.digikey.com/product-detail/en/analog-devices-inc/AD590JF/AD590JF-ND/611802
It's not as small as a thermistor, but not overly large. They have other
packages as
Matthias,
How about a 'quick and dirty, hand wavey' graph?
This is a known 'kinda good' OCXO, that was off for about a year. The
DAC values are just that, DAC counts. The black line should represent
about 8e-12 per day drift. (Sorry, I don't have better numbers than that
easily on hand). I
Just a thought:
https://www.analog.com/media/en/technical-documentation/data-sheets/hmc438.pdf
Although it isn't really 'low power', and the input and output ranges
are somewhat limited. Certainly not logic level.
Dan
On 7/1/2020 2:50 AM, time-nuts-requ...@lists.febo.com wrote:
Message:
Hi,
Sorry, I had to jump in here. Ceramic capacitors are NOT less likely to
suffer damage hand soldering. They are very susceptible to damage hand
soldering. This is especially true if you are using the larger sizes
(1206 and up).
Placing the tip of a hot soldering iron against the end of
So, Just a few numbers to look at.
I'm currently starting at a GPSDO output. The DAC is a PWM DAC with 20
bit resolution. Note the previous replies in regards to the PWM. Also
note, PWM is used here as the DAC in the micro was so poor it was not
usable to drive the EFC lead.
The DAC covers
Hi All,
Just to clarify, the PLL we're looking for only needs to do the 10 ->
125MHz. The 125 ->MHz 3.125GHz is in a separate device with it's own
PLL. I have some, but not a lot of control over that. The goal here is
to provide a good source for the 125Mhz, for not a lot of board space
and
Hi All,
We've got a project going on where we need a 125MHz clock that should be
locked to 10MHz. I'm considering an on board 10MHz oscillator and
external 10MHz input to utilize an external standard to lock the 125MHz
which would PLL a 125MHz source.
The 125MHz becomes a reference for
Paul,
To me it appears that "A" frame supporting half of the wire is a spring.
It only makes sense the designers would want some axial tension. The "A"
frame shape would supply axial load while providing excellent radial
stability in all directions. (If this isn't the case, why is that
So,
If I'm interpreting the pictures correctly, It appears the hot wire
ionizer wire is spring loaded. It would probably take a significant
impact to spring that back enough for the wire to weld back with any
sort of discharge.
It may be possible, but most likely not very easy to do.
Hi All,
Just to be clear, the request was about which multi-band antenna to buy.
I'd like to play with the new F9P or F9T GPS modules. The Chinese unit
from ebay is now in hand, and I need a free weekend to build a mount for
the house.
For those concerned with the lightning aspect, The hits
Hi All,
So it appears several of you have played with the BME280 chip. (Posts
below...)
A while back I started a project with the BME280 that I didn't around to
finishing. Basically, A BME280, PIC24, and Serial to USB cable.
The idea WAS to build a temp/pressure/humidity logger for time
John,
Yes, I have a polyphaser in line.
Currently the antenna run is long, and I think it's the inductive pickup
from nearby strikes or cloud to cloud that's popping the antennas. I'm
looking at shortening the run. That will cost me the 360deg sky view
down to near 20deg, but at this point
Hi All,
For the second summer in a row we were smacked with lightning. So I'm in
need of a new GPS antenna. Might as well look for one with multi band
units. I recall some talk about the cheap multi-band units on ebay that
that are compatible with the f9P modules. Can anyone report back how
The 87 is a good general purpose meter. My preference has been the now
obsolete Fluke 189. It was replaced with the 289, which is just
horrible. It eats batteries, is huge, takes forever to 'boot'. No one in
the ship grabs that one unless it's the last one on the shelf.
We've gone to orange
Bob,
I recalled the plot you posted a few days ago. Nice plot on the F9P,
BTW. Thanks for posting that.
I don't supposed you happened to be recording a similar plot with a L1
only Ublox part at the same time by chance, did you? I think it would be
interesting to compare a 6T or M8 part to
Hi,
As I'm inclined pop my head up and throw my opinion in here...
Since the internal clock (ring oscillator) is essentially free running
in the TDC7200 it really has a 55ps +/- xxx ps resolution. That is to
say, it may be 55ns, or 55.001ns, or 54.999ns resolution. It's possible
those extra
On 10/30/2018 9:55 AM, time-nuts-requ...@lists.febo.com wrote:
My MDO3024 (a modern scope) can measure delay and phase between two inputs,
using the measured zero crossings, including statistics of the measurement.
If you can obtain a similar scope, you could use two identical 1 Meg probes
Bob,
I think what you want is the SX-Key editor, which includes the compiler
and programmer and help files.
https://www.parallax.com/downloads/sx-key-editor-software
In fact, just earlier today I programmed SX processor on a board...
Dan
On 9/12/2018 12:00 PM,
FYI,
I would tend to agree about the drop in traffic. Not sure if it's just a
quiet period, but there are many less messages than before in the digest.
Dan
On 7/23/2018 12:00 PM, time-nuts-requ...@lists.febo.com wrote:
Could it be that the reflector drops messages?
I did not get
Hi,
I have (or had, I guess) a GPS antenna on a tower that took a lightning
hit yesterday.
You can tell it's going to be a bad day when you walk into your shop,
and smell burnt electronics. Still have to troubleshoot exactly what got
hit, but the GPSDO was flashing no GPS signal, the 5V
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