[time-nuts] Ublox 8T

Thu Dec 10 00:07:46 UTC 2020

Bob

I'm with you on jlcpcb -- I actually have two different designs with 10 of
each, with components installed winging their way to me at the moment for a
grand total of $85 including shipping. Yes, not complicated boards, but
still fun to design and get built. One of them is of vague interest to this
group as it is a pendulum timer to monitor pendulum swings and generate log
of the clock performance. Lots of interesting details come out of the
data....

Philip

On Wed, Dec 9, 2020 at 6:03 PM Bob kb8tq <kb8tq at n1k.org> wrote:

> Hi
>
> What you want around the uBlox depends a lot on what you are trying to do.
>
> These days, putting an MCU directly on this or that is a pretty cheap
> option.
> (very much so if you are using JLPCB).
>
> Do you isolate / buffer this or that?  Full RS-232 I/O adds a chip and a
> few parts.
>
> Do you regulate this and that on the board? Is the antenna supply
> independent of
> the module? Do you have full sensing on the antenna supply?
>
> For some, part of the mix is a delay chip to handle the sawtooth
> correction. Very
> much a “that depends” sort of thing.
>
> Do you put a counter / TDC of some sort on the board to do a compare to an
> external
> PPS? (At this point this list just about has a full GPSDO buried in it ….)
>
> Lots of choices and lots of directions you could go.
>
> One of the reasons I really like JLPCB is that you can do up 5 of a board
> like this,
> with a lot of parts populated and still not have spent $100 (delivered
> ….).  As long
> as you have confidence in the footprints, the risk is pretty small.
>
> One note: JLPCB is the only “fab + assembly” outfit I’ve tried. Their
> boards are
> no better / no worse than a lot of other board fab outfits. I have no idea
> how they
> compare to other assembly houses. My selection criteria: “ are they the
> cheapest
> I can find?” :)
>
> Bob
>
> > On Dec 9, 2020, at 5:35 PM, Matthias Welwarsky <time-nuts at welwarsky.de>
> wrote:
> >
> > On Mittwoch, 9. Dezember 2020 21:46:25 CET Philip Gladstone wrote:
> >> I have used the assembly service from jlcpcb a few times for small runs
> --
> >> it is absurdly cheap *if* you are using common surface mount components
> and
> >> cheap for the less common ones. I then hand solder the connectors on
> when I
> >> get the boards.
> >
> > That's what I typically do as well. But you don't need a lot of support
> > components for a M8T, it's almost not worth it. Effectively, you have
> >
> > 3 parts for the antenna power feed-in
> > 1 decoupling cap for the module itself
> > 1 resistor or ferrite bead for each signal you need to break out
> > 3(4) parts for the power supply (LDO)
> >
> > USB needs just a few more parts, two resistors, a protection chip and a
> > receptacle.
> >
> >
> >>
> >> Philip
> >>
> >> On Wed, Dec 9, 2020 at 3:27 PM Matthias Welwarsky <
> time-nuts at welwarsky.de>
> >>
> >> wrote:
> >>> On Mittwoch, 9. Dezember 2020 14:57:55 CET Bob kb8tq wrote:
> >>>> Hi
> >>>>
> >>>> I think the key point is:
> >>>>
> >>>> *IF* somebody wants to do a layout using the M8T, Bert already *has* a
> >>>> “known good” PCB layout footprint in his inventory of useful stuff.
> >>>> Since
> >>>> the uBlox is a really odd part, you aren’t going to find that
> footprint
> >>>> built into the standard layout programs.
> >>>
> >>> I have a known-good footprint and symbol for KiCAD, if anyone is
> >>> interested. I
> >>> also have KiCAD project for a small breakout board. It's not too
> >>> featureful,
> >>> no antenna power switching or monitoring, no support for antenna power
> >>> other
> >>> than from the built-in LDO. However, it has been successfully used in a
> >>> GPSDO
> >>> project. All components are hobbyist-friendly 0805, except for a LDO
> with
> >>> SOT-23-5 footprint.
> >>>
> >>>> Bob
> >>>>
> >>>>> On Dec 8, 2020, at 6:26 PM, Bill Notfaded <notfaded1 at gmail.com>
> wrote:
> >>>>>
> >>>>> That's a really old board though.  An 8 series isn't pin compatible
> >>>
> >>> with
> >>>
> >>>>> say LEA-6T is it?  The picture had a 5 series in it.
> >>>>>
> >>>>> Could you use something like this?
> >>>
> >>>
> https://github.com/PaulZC/NEO-M8T_GNSS_FeatherWing/blob/master/LEARN.md
> >>>
> >>>>> Bill
> >>>>>
> >>>>> On Tue, Dec 8, 2020, 10:30 AM Gregory Beat via time-nuts <
> >>>>>
> >>>>> time-nuts at lists.febo.com> wrote:
> >>>>>> There are various Breakout (bare) Boards for the uBlox modules
> posted
> >>>
> >>> on
> >>>
> >>>>>> Internet.
> >>>>>> SparkFun has carried them, in the past, and sometimes sold the bare
> >>>>>> boards
> >>>>>> without the uBlox module.
> >>>>>> https://www.sparkfun.com/products/15005
> >>>>>>
> >>>>>> StuartsProjects (Stuart Robinson, Cardiff, UK) has a bare board for
> >>>
> >>> the
> >>>
> >>>>>> Ublox MAX M8Q module.  Sold on Tindie, used in high-altitude balloon
> >>>>>> projects.
> >>>
> >>>
> https://www.tindie.com/products/stuartsprojects/ublox-max-8mq-gps-breakou
> >>>
> >>>>>> t-board-x-2/
> >>>>>>
> >>>>>> Contact Limor “Ladyada” Fried at Adafruit, she might have bare
> boards
> >>>
> >>> OR
> >>>
> >>>>>> Gerbers for earlier or future products.
> >>>>>> https://www.adafruit.com/?q=gps+breakout&p=1&sort=BestMatch
> >>>>>>
> >>>>>> Dan Watson designed one, for the 6-series five years ago.
> >>>>>> He sometimes posted Gerber files.
> >>>
> >>>
> http://syncchannel.blogspot.com/2015/09/a-nearly-perfect-u-blox-gps-break
> >>>
> >>>>>> out.html
> >>>>>>
> >>>>>> greg
> >>>>>> w9gb
> >>>>>> ==
> >>>>>> Date: Mon, 7 Dec 2020 09:47:55 -0500
> >>>>>> From: paul swed <paulswedb at gmail.com>
> >>>>>> To: Discussion of precise time and frequency
> >>>>>>
> >>>>>>  measurement <time-nuts at lists.febo.com>
> >>>>>>
> >>>>>> Subject: Re: [time-nuts] Ublox 8T
> >>>>>>
> >>>>>> Bert Very attractive price. They appear to be on a cut out circuit
> >>>
> >>> board.
> >>>
> >>>>>> How are you connecting to them please?
> >>>>>> Regards
> >>>>>> Paul.
> >>>>>> WB8TSL
> >>>>>> _______________________________________________
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> >>>>>> and follow the instructions there.
> >>>>>
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> >>>>
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> >>
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> >
> >
> >
> >
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