Parts

678 Articles

Experimenting With 20 Meters Of Outlet Adapters

February 4, 2023 by 100 Comments

You may have seen some of the EEVblog dumpster dive videos, where [Dave Jones] occasionally finds perfectly good equipment that’s been tossed out. But this time, rather than a large screen monitor, desktop computer, or a photocopier, he features a stash of 283 electrical outlet double adapters that he found last year. He decided to perform a test in the parking lot, connecting all 283 adapters in series.

Using a pair of power meters and a 2 kW electric heater as a test load, [Dave] and his son [Sagan] measure the loss through this wild setup. It works out to about about 300 W, or roughly 1 W per adapter. He did a follow-up experiment using a FLIR thermal camera, and confirmed that the power loss is reasonably uniform, and that no single rogue adapter consuming all the lost power. After a back of the envelope calculation, we estimate this chain of adapters is about 20 meters long, making this whole thing entirely pointless but interesting nonetheless. Stick around until the end of the video for a teardown — they’re not as cheaply made as you might think.

[Dave]’s crazy experiment aside, we do wonder why someone had so many adapters to throw away in the first place. What would you have done with 283 adapters — left them in the dumpster or rescued them?

Continue reading “Experimenting With 20 Meters Of Outlet Adapters” →

Showing two MCP23017 expanders soldered onto a PCB

MCP23017 Went Through Shortage Hell, Lost Two Inputs

February 3, 2023 by 68 Comments

The MCP23017, a 16-bit I2C GPIO expander, has always been a tasty chip. With 16 GPIOs addressable over I2C, proper push/pull outputs, software-enabled pull-ups, eight addresses, maskable interrupts for all pins, and reasonably low price, there’s a reason it’s so popular. No doubt due in part to that popularity, it’s been consistently out of stock during the past year and a half, as those of us unlucky enough to rely on it in our projects will testify.

Now, the chip is back in stock, with 23,000 of them to go around on Mouser alone, but there’s a catch. Apparently, the lengthy out-of-stock period has taken a heavy toll on the IC. Whether it’s the recession or perhaps the gas shortages, the gist is — the MCP23017 now a 14/16-bit expander, with two of the pins (GPA7 and GPB7) losing their input capabilities. The chips look the same, are called the same, and act mostly the same — if you don’t download the latest version of the datasheet (Revision D), you’d never know that there’s been a change. This kind of update is bound to cause a special kind of a debugging evening for a hobbyist, and makes the chip way less suitable for quite a few applications.

It’s baffling to think about such a change happening nearly 20 years after the chip was initially released, and we wonder what could have caused it. This applies to the I2C version specifically — the SPI counterpart, MCP23S17, stays unaffected. Perhaps, using a microcontroller or shift registers for your GPIO expansion isn’t as unattractive of an option after all. Microcontroller GPIO errata are at least expected to happen, and shift registers seem to have stayed the same since the dawn of time.

The reasons for MCP23017 silicon getting cut in such a way, we might never know. At least now, hopefully, this change will be less of a bitter surprise to those of us happy to just see the chip back in stock — and for hackers who have already restocked their MCP23017 hoards, may your shelved boards magically turn out to have a compatible pinout.

Brass Hardware Makes For Pretty Potentiometer Knobs

February 2, 2023 by 18 Comments

Knobs and switches can make or break the aesthetic and tactile appeal of a project. Fine hi-fi hardware goes hard on these details, while cheap knock-off guitar pedals often go the other way. If you’re looking for a unique, cheap, and compelling solution for potentiometer knobs, you might like to consider using converted brass hardware for the job.

Gorgeous, no?

The idea comes from [Kevin Jordan], who realized that some simple 3D printed parts would enable him to repurpose brass hardware for use with common split-shaft potentiometers. He grabbed a bunch of brass flare caps intended for use with gas piping, and got to work.

The result is the simple 3D printed cap converter. It has a threaded outer portion, which screws neatly inside a brass flare cap. Inside, it features a hole to mate to the potentiometer shaft. While this could be done with a spline, it also works with a simple hole since the plastic is soft enough to simply push the potentiometer shaft into.

The flare caps look great when pressed into service as knobs. [Kevin] uses them on a tennis racket guitar he built, and the brass knobs beautifully set off against the natural wood finishes of the build. If you’re looking for some unique adornments for your own projects, you might like to experiment with this concept yourself! Alternatively, you can try making your own knobs from scratch.

Continue reading “Brass Hardware Makes For Pretty Potentiometer Knobs” →

Copy And Paste Lithium Battery Protection

February 2, 2023 by 40 Comments

Lithium batteries have, nearly single-handedly, ushered in the era of the electric car, as well as battery energy storage of grid power and plenty of other technological advances not possible with older battery chemistries. There’s just one major downside: these lithium cells can be extremely finicky. If you’re adding one to your own project you’ll have to be extremely careful to treat them exactly how they are designed to be treated using something like this boilerplate battery protection circuit created by [DIY GUY Chris].

The circuit is based around the TP4056 integrated circuit, which handles the charging of a single lithium cell — in this design using supplied power from a USB port. The circuit is able to charge a cell based on the cell’s current charge state, temperature, and a model of the cell. It’s also paired with a DW01A chip which protects the cell from various undesirable conditions such as over-current, overcharge, and over-voltage.

The best thing about this design isn’t the design itself, but that [DIY GUY Chris] built the circuit schematic specifically to be easily copied into PCB designs for other projects, which means that lithium batteries can more easily be integrated directly into his other builds. Be sure to check out our primer on how to deal with lithium batteries before trying one of your own designs, though.

Continue reading “Copy And Paste Lithium Battery Protection” →

Retro Computer Enclosure Without The Sacrifice

January 30, 2023 by 29 Comments

The unique look of early desktop computer systems remains popular with a certain segment of geekdom, so it’s no great surprise when we occasionally see a modern hacker or maker unceremoniously chuck 40+ year old electronics from a vintage machine just to reuse its plastic carcass. We try not to pass judgement, but it does sting to see literal museum pieces turned into glorified Raspberry Pi enclosures.

But with a little luck, perhaps the Retro Wedge Computer case designed by [AndyMt] will be able to save a few of those veteran computers from an unnecessary lobotomy. As the name implies, this 3D printable model is designed to resemble “wedge” desktop computers such as the Atari ST, TI-994A, and Commodore 128. But don’t be put off by its considerable size — the model has been chopped up so no piece is larger than what can fit on a fairly standard 230 x 230 mm print bed. Continue reading “Retro Computer Enclosure Without The Sacrifice” →

A black quadcopter sits on a grey surface. In place of traditional propellers are four figure eight propellers with sharp tips where the top and bottom of the eight would be.

Toroidal Propellers Make Drones Less Annoying

January 28, 2023 by 60 Comments

Despite being integral to aviation for more than a century, propellers have changed remarkably little since the Wright Brothers. A team at MIT’s Lincoln Lab has developed a new propeller shape that significantly reduces the noise associated with drones. [PDF via NewAtlas]

Inspired by some of the experiments with “ring wings” in the early 20th Century, researchers iterated on various toroidal propeller geometries until arriving at one that significantly reduces the sound produced by the rotors, particularly in the range of human hearing. The team suspects the reduction in noise is due to vortices being distributed over the whole propeller instead of just the tips.

Experiments show the drones can get twice as close before becoming a nuisance for human ears which should be great news for anyone hoping to launch Skynet commercial drone deliveries. Since the rotors are easily fabricated via 3D printing they should be easy to adapt to a number of different drones.

If you want to explore some more interesting drones, checkout this one that can fly and swim or this one that only uses a single propeller.

Casting Custom Resin Buttons For The Steam Deck

January 26, 2023 by 11 Comments

If you play games on multiple consoles, you’re probably familiar with the occasional bout of uncertainty that comes with each system’s unique button arrangement. They’re all more or less in the same physical location, but each system calls them something different. Depending on who’s controller you’re holding, the same button could be X, A, or B. We won’t even get started on colors.

Overhearing her partner wish the buttons on his Steam Deck matched the color scheme of the Xbox, [Gina Häußge] (of OctoPrint fame) decided to secretly create a set of bespoke buttons for the portable system. There was only one problem…she had no experience with the silicone molding process or epoxy resins which would be required for such an operation.

Toothpicks were used to make channels in the mold.

Luckily we have the Internet, and after researching similar projects that focused on other consoles, [Gina] felt confident enough to take apart Steam’s handheld and extract the original plastic buttons. These went into a clever 3D printed mold box, which was small enough to put into a food vacuum container for degassing purposes. The shape of the buttons necessitated a two-piece mold, into which [Gina] embedded two channels: one to inject the resin, and another that would let air escape.

The red, green, blue, and yellow resins were then loaded into four separate syringes and forced into the mold. It’s critically important to get the orientation right here, as each button has a slightly different shape. It sounds like [Gina] might have mixed up which color each button was supposed to be during an earlier attempt, so for the final run she made a little diagram to keep track. After 24 hours she was able to peel the mold apart and get a look at the perfectly-formed buttons, but it took 72 hours before they were really cured enough to move on to the next step.

[Gina] applied the legends with a sheet of rub-on lettering, which we imagine must have been quite tricky to get lined up perfectly. Since the letters would get worn off after a few intense gaming sessions without protection, she finally sealed the surface of each button by brushing on a thin layer of UV resin and curing it with a flashlight of the appropriate wavelength.

There are a fair number of steps involved, and a fair bit of up-front cost to get all the materials together, but there’s no denying the final result looks phenomenal. Especially for a first attempt. We wouldn’t be surprised if the next time somebody wants to head down this particular path, it’s [Gina]’s post that guides them on their way.