Ask Hackaday: With Landline Use In Decline, What’s To Be Done With The Local Loop?

Walking is great exercise, but it’s good for the mind too: it gives one time to observe and to think. At least that’s what I do on my daily walks, and being me, what I usually observe and think about is the local infrastructure along my route. Recently, I was surprised to see a number of telephone company cabinets lying open next to the sidewalk. Usually when you see an open box, there’s a telephone tech right there, working on the system. But these were wide open and unattended, which I thought was unusual.

I, of course, took the opportunity to check out the contents of these pedestals in detail. Looking at the hundreds of pairs of brightly colored wire all neatly terminated and obviously installed and maintained at great expense, I was left wondering why someone would leave such a valuable asset exposed to the elements. With traditional POTS, or plain old telephone service, on the decline, the world may no longer have much use for the millions of miles of copper cable feeding back to telco central offices (COs) anymore. But there’s got to be something this once-vital infrastructure is still good for, leading me to ask: what’s to be done with the local loop?

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Brass And Nickel Work Together In This Magnetostrictive Earphone

When you go by a handle like [Simplifier], you’ve made a mission statement about your projects: that you’ll take complex processes and boil them down to their essence. So tackling the rebuilding of the humble speaker, a device he himself admits is “both simplified and optimized already,” would seem a bit off-topic. But as it turns out, the principle of magnetostriction can make the lowly speaker even simpler.

Most of us are familiar with the operation of a speaker. A powerful magnet sits at the center of a coil of wire, which is attached to a thin diaphragm. Current passing through the coil builds a magnetic field that moves the diaphragm, creating sound waves. Magnetostriction, on the other hand, is the phenomenon whereby ferromagnetic materials change shape in a magnetic field. To take advantage of this, [Simplifier] wound a coil of fine copper wire around a paper form, through which a nickel TIG electrode welding filler rod is passed. The nickel rod is anchored on one end and fixed to a thin brass disc on the other. Passing a current through the coil causes the rod to change length, vibrating the disc to make sound. Give it a listen in the video below; it sounds pretty good, and we love the old-time look of the turned oak handpiece and brass accouterments.

You may recall [Simplifier]’s recent attempt at a carbon rod microphone; while that worked well enough, it was unable to drive this earphone directly. If you need to understand a little more about magnetostriction, [Ben Krasnow] explained its use in anti-theft tags a couple of years back.

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Design And Construction With Copper Pipe

Copper is a material with many applications; typically, it’s used for electrical wiring or in applications where good heat conductivity is a requirement. However, it can also make for an attractive material in furnishings, which [Andrei Erdei] decided to explore.

A render of the coffee table design, exported from OpenSCAD into Fusion360.

[Andrei]’s work began in OpenSCAD, where he wrote scripts to enable the quick and easy assembly of various designs. The modular nature of commercially-available copper pipe and fittings allows complex structures to be assembled, particularly if you’re a fan of 90-degree bends. The final renders of some of these designs are impressive, with the coffee table design a particular highlight. Staying conceptual wasn’t enough, however, so [Andrei] set out to build one of his designs. Constructing a table lamp shroud out of copper parts was successful, though the real components have flanges and other features that aren’t represented in the rendering.

It’s a project that shows the value of tools such as OpenSCAD to aid the design process before committing to cutting real-world materials. While the designs on screen aren’t perfect representations of what’s possible in reality, it still proves to be a useful guide.

We’re a fan of the aesthetic, and would love to see more done with copper pipe as a construction kit. Global ore prices may limit experimentation, however. Alternatively, you can always harvest the metal from scrap!

Drill Thrice, Solder Once

If you design printed circuit boards, then you will have also redesigned printed circuit boards. Nobody gets it right the first time, every time. Sometimes you can solder a scrap of 30gauge wire, flip a component 180°, or make a TO-92 transistor do that little pirouette thing where the legs go every-which-way. If you angered the PCB deities, you may have to access a component pad far from an edge. [Nathan Seidle], the founder of Sparkfun, finds himself in this situation, but all hope is not lost.

Our first thought is to desolder everything, then take a hot iron and tiny wires to each pad. Of course, this opens up a lot of potential for damage to the chip, cold joints, and radio interference. Accessing the pin in vivo has risks, but they are calculated. The idea is to locate the pin, then systematically drill from the backside and expose the copper. [Nate] also discovers that alcohol will make the PCB transparent so you can peer at the underside to confirm you have found your mark.

In a real, “fight fire with fire” idea, you can rework with flex PCBs or push your PCB Fu to the next level and use PCBs as your enclosure.

Make An Electroplating Marker, Because Plating Complex Objects Is Hard

If an object is conductive or has been given a conductive coating, it can be given a metal skin via electroplating. Electroplating is a simple process that is perfectly accessible to anyone in possession of vinegar, salt, a power supply, and some metal such as copper or nickel.

The process might be simple, but as with all such things there are a few gotchas. One of them is this: because electricity follows the path of least resistance, recessed areas of an object may not electroplate well (or at all) no matter how long the object is left immersed. To address this, [Brodie Fairhall] designed a 3D printed electroplating marker. The marker is essentially a more refined version of brush plating, and allows more precision and control than full immersion in an electrolyte bath.

[Brodie] created an excellent video that explains all one needs to start electroplating, and demonstrates using his marker to electroplate complex recessed shapes. Watch him coat a 3D-printed cat pendant in both copper and nickel in the video embedded below. It’s concise, well-edited, and chock full of useful tips.

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Epoxy Fix For A Combusted PCB

When the Magic Smoke is released, chances are pretty good that you’ve got some component-level diagnosis to do. It’s usually not that hard to find the faulty part, charred and crusty as it likely appears. In that case, some snips, a new non-crusty part, and a little solder are usually enough to get you back in business.

But what if the smoke came not from a component but from the PCB itself? [Happymacer] chanced upon this sorry situation in a power supply for an electric gate opener. Basking in the Australian sunshine for a few years, the opener started acting fussy at first, then not acting at all. Inspection of its innards revealed that some unlucky ants had shorted across line and neutral on the power supply board, which burned not only the traces but the FR4 of the board as well. Rather than replace the entire board, [Happymacer] carefully removed the carbonized (and therefore conductive) fiberglass and resin, leaving a gaping hole in the board. He fastened a patch for the hole from some epoxy glue; Araldite is the brand he used, but any two-part epoxy, like JB Weld, should work. One side of the hole was covered with tape and the epoxy was smeared into the hole, and after a week of curing and a little cleanup, it was ready for duty. The components were placed into freshly drilled holes, missing traces were replaced with wire, and it seems to be working fine.

This seems like a great tip to keep in mind for when catastrophe strikes your boards. There are more extreme ways to do it, of course, but perhaps none so flexible. After all, epoxy is versatile stuff.

Touch Anything And Everything

Powering IoT devices is often a question of batteries or mains power, but in rare exceptions to this rule there is no power supply (PDF Warning). At the University of Wisconsin-Madison and the University of California, San Diego, researchers have gone the extra mile to make advanced backscatter devices, and these new tags don’t need the discrete components we have seen in previous versions. They are calling it LiveTag, and it doesn’t need anything aside from a layer of foil printed or etched on a flexible ceramic-PTFE laminate. PTFE is mostly seen in the RF sector as a substrate for circuit boards.

We have seen some of the wild creations with wifi backscatter that range from dials to pushbuttons. RF backscatter works by modulating the RF signals in which we are continuously swimming. Those radio waves power the device and disrupt the ambient signals, which disruption can be detected by a receiver. With a BOM that looks like a statement more than a list, integration with many devices becomes a cost-effective reality. Do not however broadcast important data because you cannot expect great security from backscatter.

[Via IEEE Spectrum]