Electronics > Projects, Designs, and Technical Stuff
GPSDO: PLL or MCU controlled?
Johnny B Good:
--- Quote from: Illusionist on August 22, 2019, 03:12:31 am ---Sounds like you're keeping busy there!
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It's always like that after these cruise holidays which the XYL loves so much (I'm not so keen - given my way, I'd rather avoid any such disruption to my own interests - I always feel that I could do with a holiday break to get over the holiday break, a feeling that seems to be shared by many others).
--- Quote from: Illusionist on August 22, 2019, 03:12:31 am ---
--- Quote from: Johnny B Good on August 22, 2019, 02:11:46 am ---BTW, that bottle of RA flux you linked to on Farnel's site costs three quarters the price of the KSGER soldering station which seems eye wateringly expensive to me. Just how long does a 125mL bottle of this magic RA flux last for? ::) ;)
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I had to check... they put the price up, just a little. I must admit I thought it was cheap in comparison to the others... it was £6.90 when I bought it. Must have been an error. As to how long it will last, likely as long as I'll be soldering.
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Just a little! Blimey, that's a bit of an understatement! ::)
--- Quote from: Illusionist on August 22, 2019, 03:12:31 am ---I also bought a pot of this the other day, because I needed something that only Farnell had in stock and wanted to make the order up to £20:
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I know what you mean. BTDTAGTBTS when I was ordering a 3 cell NiMH replacement battery from CPC a few years ago for my Potterton CH controller - the tagged version was far cheaper than the plug in version used by the controller so tagged version it was. I ripped the tags off and dressed the ends with a fine file and it did the job perfectly - a little too well since the trick of switching off at the mains and wait a few hours with the original Nicad to force a reset no longer works, not even if left off over a long weekend! >:( I'd added a couple of Bosch 40W oven bulbs to that order and still had to find some tat to make up the minimum (pre-VAT) order value to escape the delivery charges.
--- Quote from: Illusionist on August 22, 2019, 03:12:31 am ---
https://uk.farnell.com/mg-chemicals/8342-50g/ra-rosin-flux-paste-37-7ml-50g/dp/3018421
It's £6 a pot, still, and works just as well as the liquid. It's a bit easier to control too. I just paint it on where needed with a sliver that I cut off an antistatic rubber mat.
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Now, that I could afford but apparently you can do even better with a 23 quid ONE Litre bottle of the magic RA flux from Farnell which works out at just £2.875 per 125mL. It looks like Farnell made a decimal point error in their 125ml pricing calculation. ::) :-//
I've just taken a closer look at my radioham rally purchases of soldering flux (a small 10g tub of "Duratool" Solder Paste - melting point 38-60 deg C) and a 10ml Yosker flux pen of 'no-clean flux'. Checking the duratool.co.uk web address gave a server not found error but googling took me to CPC/Farnell revealing it to be a current product made in china (as per the sticker).
Interestingly, it was a little harder to track down information on the Yosker flux pen but I did land up on an Amazon page, and this is the interesting bit, where I spotted a 125ml bottle of that magic RA liquid flux in the "Customers who viewed this item also viewed" section priced, more reasonably at a mere £8.35 ::) There's no doubt about it, that one litre bottle of the stuff being sold for a mere 23 quid on Farnell's site is an unmissable bargain! ::) :wtf: The only problem, unless I go into the repackaging/profiteering business, is that it's likely to expire its BBD long before I get to use even a small fraction of the contents. :( BTW, can you tell me what its storage lifetime is? I couldn't find any specification on this.
[EDIT]
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Belay that last question! I followed the link to the one litre bottle and found my answer in the technical datasheet - it's 5 years after date of manufacture for storage conditions of 18 to 27 deg C. Presumably it could last a lot longer if stored in a fridge (5 to 8 deg C).
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Oh, yes, I almost forgot, I did notice that that Yosker flux pen had been given very favourable customer reviews along with a helpful warning to store it upright after first use (it tends to leak otherwise, apparently).
--- Quote from: Illusionist on August 22, 2019, 03:12:31 am ---
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As to my GPSDO, I now have my derived PPS synchronized to within 500ps of the GPS second (minus its jitter thanks to Kalman). Its phase is adjustable in 500ps steps up to 100ns in front of the second, to account for cable delay etc.
The core design is settled now. I've decided to add a small Nextion display to it for statistics, and use some of the spare dsPIC horsepower to run a couple of user configurable frequencies/PWM outputs. I don't have much desk space, so adding that facility will save pulling my AWG out of the drawer and clearing space for it when I just need a simple source.
The last major thing to do is test my output circuits on the breadboard. They seem fine in Multisim.
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My ambitions at the moment are somewhat more modest right now. It'll be good to get a first working DIY GPSDO up and running for the time being (it's only taken me some 6 months or so to get to the threshold of assembling a nice stable version of the breadboarded design onto veroboard and into a handy little metal enclosure). I've got another six of the 12v 10MHz CQE OCXOs going spare (the seventh is already installed in my FY6600 sig genny - they look identical to that 5v 13MHz one I'm using in the current project) which I plan to use in more ambitious future GPSDO projects. ;)
JBG
Johnny B Good:
--- Quote from: Illusionist on August 22, 2019, 04:53:52 am ---That bottle of flux that has gone up to £29 for 125ml... Farnell has the 1 litre bottle for £23.
https://uk.farnell.com/mg-chemicals/835-1l/rosin-soldering-flux-bottle-1l/dp/2903910
Someone there can't sort their pricing out!
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Indeed! Working out the price per 125ml from the 1l bottle price, one might almost be tempted to think they'd shifted the decimal point one place to the right by mistake in their calculation (force of habit maybe? ::) ) Still, it's only just over three times its price on Amazon. >:D Perhaps Farnell have deliberately over-priced the 125ml bottles to tempt prospective customers into purchasing the 1 litre bottles before they exceed their DOM 5 year limit and become unsaleable.
I did briefly consider the possibility of purchasing a "Lifetime's Supply" until I considered the probable issue of a limited storage life putting a big dent into that plan. I rather fancy that even storing the bulk of a 1 litre bottle's worth in the fridge to get a ten year or longer shelf life would still leave me with a sizeable unused surplus even if I were to be profligate in my use of the stuff so quashed all thoughts of spending 23 quid with Farnell.
Buying such 'consumables' in smaller quantities, as and when the need arises, seems a far more sensible plan in this case. Besides which, at this stage of the game, there's little point in buying the larger, more economic quantities until I have a better idea of my actual usage rate, plus it's better to have a small range of solder flux types better matched to any individual usage cases that arise. In any case, I won't be spending my money on luxury items such as that 29 quid 125ml bottle of magic flux from the likes of Farnell. >:D
JBG
Johnny B Good:
--- Quote from: David Hess on August 22, 2019, 11:56:25 am ---Kester used to sell flux and other chemicals in 4 ounce glass bottles but they stopped like 20+ years ago. I have a few marked as 1992.
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Which rather begs the question, are they still within their BBD? >:D I take it that this stock of ancient flux of yours hasn't presented you with any issues over expired BBDs or DOM life expiry limits?
Talking of soldering kit of such vintage, I was browsing the soldering section of Banggood's site just a few minutes ago (as one does) when I spotted this rather neat item (obviously no BBD issues here ;) ) :-
https://www.banggood.com/Hand-Soldering-Iron-Stand-Helping-Clamp-Magnifying-Tool-Auxiliary-Clip-Magnifier-Station-Holder-p-1017105.html?rmmds=detail-bottom-alsobought__16&cur_warehouse=CN
Which looked oh so familiar :palm: Familiar indeed because I already have one to hand which has mostly been gathering dust on the shelf of a roller blind cupboard (never ever closed, btw) in my office/man-cave/workshop for the past two to three decades. :-[ If I didn't already possess the exact same aid, I would have placed an order with Banggood right there and then!!!
That's obviously had at least a three decades long production run (possibly even half a century or longer!) which is unusual to see with Banggood stock. The annoying thing is that I must have struggled many a time over the past twenty or thirty years, soldering small items and circuit boards without its aid - talk about old habits dying hard! :palm:
When I first clapped eyes on those pictures of that "Helping Hands with magnifying glass stand", I did briefly consider whether they'd employed an agent to sneak into my man cave to dust mine off and take all those photos. :)
I'm surely not alone in having such a :palm: experience? I mean, it's a little embarrassing in a way to admit to such a protracted oversight (twenty or more years worth!) but I feel it's better to have a laugh about it rather than silently mope over allowing such a useful aid to go unused for all those years simply through the sheer force of (dumb) habit. ::)
JBG
Dbldutch:
Illusionist, since you seem to have some spare development boards available, would you mind publishing the circuit diagram for them? It’s early days for me in this process, but I might be interested in buying one from you.
Tks,
Paul
Illusionist:
Paul, I haven't published the diagrams here only because I made a mistake with the design. The mistake doesn't effect me at all, and might not effect you, but I didn't want to publish a board with a mistake on it.
That said, I'll PM the files to you later today for you to look at, and I'll point out the mistake. If you still want one, you can have a board for the cost of posting it.
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