The Smell of Molten Projects in the Morning
Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Electrical & Electronic gadgets
This evening I’ll be showing off my Algorithmic Art at the HV Open Mad Science Fair.
There’ll be glowing glassware:
Ancient electronics with modern hardware:
Blinking LEDs atop Brutalist analog electronics:
A classic HP 7475A plotter hammering math onto paper from a Raspberry Pi running Chiplotle:
Some take-home art:
And, as always, a good time will be had by all!
As the basement’s fluorescent fixtures and lamps gradually die, I’ve been rewiring the fixtures for LED tubes, all bought from KEDSUM through Amazon. The first few batches looked like this:
The most recent two batches seem cheapnified:
The tubes show similar changes, going from a stylin’ version to a simple cylindrical cap:
The most recent carton label might lead you to think they’re counterfeits, but it could just be a simple typo:
There’s absolutely no way to tell what you’re going to get from any vendor on Amazon (or anywhere else, for that matter), so there’s no point in returning them, but I’d hoped buying “the same thing” from “the same seller” would produce a consistent result.
The tiny voice inside our Ooma Telo 2 box died, although the VOIP phone service continued to work fine. A bit of searching showed the speaker seems to be the weak link.
Well, I can fix that.
Start by prying the recessed top panel off the case:
Remove the circuit board to expose the tiny speaker, taking care not to rip the tiny wires out of the tiny connector:
You can’t measure a dead speaker, but it seems to be an 8 Ω unit.
The speaker sits in a rubber surround, with a foam rubber cushion against the PCB, tucked into a walled garden stiffening the case:
I don’t happen to have a tiny 8 Ω speaker, but I do have a bunch of small speakers (Update: 28 mm OD), so I bulldozed those walls with a flush cutting pliers and a bit of cussing to make room:
Nibble an adapter ring to match the rim of the new speaker, thereby routing the sound out those little holes, and hot-melt glue it in place:
Hot-melt glue the new speaker in place atop the adapter, taking care to fill all the edges / cracks / crevices below it with an impenetrable wall of glop:
The sealing part turns out to be critical with these little speakers, because a leak from front to back will pretty much cancel all the sound from the cone.
Cut the wires off the old speaker, affix to the new one, replace the PCB, snap the case lid in place, and it sounds better than new.
Millions of transistors in those ICs, but Ooma can’t spec a good speaker? Maybe they should have used a bigger speaker to begin with; ya never know.
My landscape monitor, a six-year-old Dell U2711, died after a few days of flickering and failure-to-start. As you’d expect with any old electronics, particularly from Dell, it’s the electrolytic caps:
All of the black-cased caps on the board had bulged cases:
They’re (allegedly) made by FOAI, for whatever that’s worth.
They’re not really capacitors any more:
I replaced all of them with cheap eBay caps to no avail. Spot-checking the other (“brown”) caps on the logic board showed they were still good, but the power supply board is firmly glued in place and I can’t get to the HV cap.
A new monitor arrived two days later and it’s all good again.
Why you shouldn’t use antistatic foam for long-term storage:
The lump emerged from Mad Phil’s parts stash, now residing under a bench at Squidwrench. The 952 date code on the HEP802 JFET suggests he tucked it in around 1980; you’re looking at nigh onto four decades of corrosion.
Memo to Self: use it or lose it!
I bought my Bose Hearphones in late August 2017, so they’re just shy of two years old, and have used them more-or-less daily since then. Although the innards still improve my hearing, the exterior is falling apart:
The conspicuous blue tips come from silicone tape holding the “soft touch” silicone shell together:
The white line seems to be silicone glue holding the hard cover plate to the equally hard base. So far, it’s working, but the two-piece soft cover is peeling away from the very thin adhesive (?) holding it to the hard parts.
The silicone glue under the flexy cover on the control pod along the right earbud cable hasn’t fared as well:
I blobbed ordinary RTV silicone under the cover, ignoring the caveats about acetic acid corrosion, because I don’t have any platinum-cure silicone on the shelf.
When the blue tape wears out / falls off, I’ll replace it with black silicone tape going further up the ring to hold the rest of the soft cover in place:
The ear buds have soft silicone strain relief tubes around the cables. The friction holding them in place failed long ago and, because no adhesive will work with silicone, I wrapped enough double-sided tape around the cables to produce a sticky lump jamming them in place:
A bit of the muck sticks out on both ends and I expect to replace the tape every now and again:
I also expect to replace the non-replaceable lithium battery / cell in about a year, as they’re now barely adequate for a day’s use.
Fortunately, I can’t see any of this hackery while I’m wearing the things:
my face I don’t mind it,
Because I’m behind it —
‘Tis the folks in the front that I jar.
https://www.azquotes.com/quote/1243103
[Update: Bose apparently had a QC failure on the silicone covering and, much to my surprise, swapped me entirely new Hearphones. The new covering feels slightly different, the USB cable hatch is a distinct piece of plastic, and maybe it’ll survive until the battery gives out. Color me satisfied! ]
I bought a pair of third-party 3800 mA·h batteries for the Baofeng UV-5RE Plus (whatever that means) radios on our bikes. Oddly, the packs carry the same “Model BL-5” identification as 1800 mA·h batteries shipped with the radio:
The obviously mislabeled “Baofeng” battery eliminator also sported a 3800 mA·h label:
I conjured a “test fixture” from a clamp, copper sheet, and copper tape snippets:
Which produced interesting results:
The 250 mA load = 15 hour rate seemed reasonable to simulate radios spending most of their time in power-save mode, but the packs still delivered only 2.8 A·h.
The packs also claim an unnaturally precise 28.12 W·h, but they’re still underperformers at 20 W·h:
Anyhow, I can run the radios for a week without (worrying about) running out of juice during a ride.
The Smell of Molten Projects in the Morning 