Posts by attie@chaos.social
(DIR) Post #AcXzlNXfrDC3LGCkts by attie@chaos.social
2023-12-06T22:30:22Z
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Just go and watch it. A really great video about electricity flow and transmission lines and stuff. Watch to 3:30 and then place your bets! (A,B,C or D)I wish ye olde name for voltage was mentioned, as it's very relevant:> Historically, voltage has been referred to using terms like "tension" and "pressure".(note to self: I really need to watch the others in the series)https://www.youtube.com/watch?v=2AXv49dDQJwhttps://en.wikipedia.org/wiki/Voltage#Definition
(DIR) Post #AcbKSJN8iAdu1C9CWu by attie@chaos.social
2023-12-08T12:45:09Z
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Uhh.. no, no... I'm good thanks.What exactly does this mean? Is there a massive download going on that I can't see or cancel?
(DIR) Post #AcssrXJPpkRA6rEzSa by attie@chaos.social
2023-12-16T13:36:10Z
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@axwax I had no idea freshly sqoze oil was "cloudy"!... will the bits settle to the top / bottom? ... and does it need to be removed / fitlered out, or is it more like bubbles that just disperse by themselves? 👀I'd love to see a "half way" photo too, if you've got one!
(DIR) Post #AdW7OcOHEawB2ilFSq by attie@chaos.social
2024-01-04T22:01:18Z
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Please help me name a unit, or find an existing prefix.NMEA provides longitude / latitude as Degrees and Arc Minutes (to 5 decimal places) - a resolution of approx 1.11m at the equator.This will translate nicely into an int32_t with units of 1e-5 arc minutes per LSB (i.e: 10 μam per LSB).What to we call 1e-5 arc minutes?... calling it 10μam feels boring, but that's where I'm currently headed.e.g:51°15.81498' N, 2°8.81592' Wbecomes+307,581,498 / -12,881,592https://maps.app.goo.gl/2uABzBLRgtdtGU3W7
(DIR) Post #AdW7OdXswMDWcoGR4y by attie@chaos.social
2024-01-04T23:03:13Z
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I think I'm settling on just referring to it as "10 μam"... I wanted to avoid confusion around "am I supposed to multiply this value by 10, or not"... but I think (hope) it'll hold together okay with worked examples.
(DIR) Post #AdW7ed9k9iKq3CbAAq by attie@chaos.social
2024-01-04T23:11:08Z
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@penguin42 10μam is ~1.11m at the equator (getting smaller towards the poles), so about 60% or less than a fathom! 🙈
(DIR) Post #AdWAwdh3CGCKn9SM4W by attie@chaos.social
2024-01-04T23:47:59Z
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@penguin42 Could be! Though the DOP may be related too (i.e: GPS is often able to give better than ~11m, but not better than ~1.1m).https://en.wikipedia.org/wiki/Decimal_degrees#Precision
(DIR) Post #AjZcMvn8MwP2if4dlI by attie@chaos.social
2024-07-03T22:51:32Z
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Join me, while I disassemble a 100BASE-ZX SFP module (1550nm, 80km)Surprisingly, these appear to be quite happy running at 1Gbit/s over ~3m of fiber! The reported Rx power doesn't even saturate for the FS.com modules (though it does for the Startech module)Oh: sorry for the bad photos... I wanted to share, but also couldn't be bothered to get the better camera (and my phone camera is terrible).
(DIR) Post #AjZcMxNKTqwxdD13om by attie@chaos.social
2024-07-03T22:55:55Z
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These modules are constructed in a delightfully simple way - a solid "chassis" is wrapped in thin steel, and these press-tabs are pushed in once assembled to hold the outer shell in place.There is one of these push tabs on each side, though they're not quite aligned. They're tricky to get out, but if you're careful, you can poke something thin all the way through!
(DIR) Post #AjZcMyxsZRmSYr7lQW by attie@chaos.social
2024-07-03T22:58:37Z
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The best way I've found to open these up, is by inserting something from one side, and pushing these tab out on the other side.I've previously used a paperclip, but it bent and was a little large... today I modified a needle by cutting the eye. I actually left the fingers a little long - I have three modules to disassemble, and one of the fingers broke off part way through the operation... they can be much shorter!
(DIR) Post #AjZcN10Qyv0qtMKpge by attie@chaos.social
2024-07-03T23:01:46Z
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Using this tool, insert it, and try to put a finger either side of the tab... then just push!You will need pliers or a sacrificial surface to push against - it's quite a stiff operation.Once you've got the tab flush with the outer body, you've actually blocked yourself from getting to the other tab. So revert to a screwdriver to open the tab the rest of the way.
(DIR) Post #AjZcN2pADnBaWz4rOi by attie@chaos.social
2024-07-03T23:07:30Z
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Once you've done one tab, and cleared the opening... do the next tab!The sheath will now slide a little more than it did before. To fully release it, you'll need to take care of the main retention mechanism that keeps the module in the parent equipment's cage. Depress the triangle, and slide the sheath further.This final clip is actuated by the main release handle, but that doesn't generally get it far enough out of the way to remove the sheath (only remove the module from the cage).
(DIR) Post #AjZcN4ZdiTxLxPpUTg by attie@chaos.social
2024-07-03T23:09:47Z
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The final hurdle is probably the label... I've taken apart some modules where the label is not an issue, and others (like this one - oopsy), where the label interferes and gets scuffed.A screwdriver can be inserted under the EMI fingers to just lift the sheath slightly away from the label.
(DIR) Post #AjZcN6K7DAj7Nqa7Ye by attie@chaos.social
2024-07-03T23:13:14Z
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We're in!The retention mechanism (handle & clip) will almost certainly fall on the table, so make sure you rescue them.There may also be a plastic shim to keep the ROSA / TOSA securely in place, but not all modules have this.Finally, a single screw will usually allow the PCB to lift away from the chassis. There are sometimes metal features on the chassis to "hold" the PCB at the far end from the screw, but not always - just be gentle and it'll come out.Watch out for a thermal interface!
(DIR) Post #AjZcN85eduLcrZpbIO by attie@chaos.social
2024-07-03T23:19:07Z
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Finally, here are all the bits.No thermal interface in this module, which was a little unexpected. If I remember correctly, the GPON modules I've opened had it... 80km is definately further, but perhaps 100Mbit/s is the key factor here for power dissipation.
(DIR) Post #AjZcN9qU7HOyJ6kVvc by attie@chaos.social
2024-07-03T23:22:51Z
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Look at the laser weld marks on the TOSA!
(DIR) Post #AkKh3IPNCYZ5tymRMW by attie@chaos.social
2024-07-25T17:03:26Z
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... I never expected to see a "This page was intentionally left blank" as a file! 😂
(DIR) Post #Al14xn2GyV6ih0CR5U by attie@chaos.social
2024-08-15T23:46:33Z
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A swing and a miss! 🤦♀️
(DIR) Post #AoiVSL8RbK3ANRfL4i by attie@chaos.social
2024-12-04T02:21:12Z
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The 32-bit CRC used by Quectel's AT+QFCRC command is a mystery, and there are a handful of unresolved posts on their support forums. I have no idea why this seems to be guarded and isn't in the manual.So here you go, in case anyone was looking. It seems to be a non-standard configuration of the common polynomial (i.e: Ethernet, Gzip, etc...)crc width=32 poly=0x4c11db7 init=0x0 xorout=0x0 refin=false refout=false out_endian=bigThanks delsum!https://github.com/8051Enthusiast/delsum
(DIR) Post #AqxQes6os7z2yCXwae by attie@chaos.social
2025-02-09T22:35:05Z
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Someone described a PCB as "epoxied", and I was about to ask if they meant "conformal coating" ... but ... wow, that is DEEP.