Archivi del mese: aprile 2020

Building a New RF Remote from Scratch

Building a New RF Remote from Scratch
By Tom Nardi

We’ve seen no shortage of projects that use the ESP8266 or ESP32 to add “smart” features to existing home appliances, often by pairing the microcontroller with a radio or IR transmitter. If your device has an existing remote, integrating it into a custom home automation system is often just a matter of getting a few cheap modular components and writing some simple code to glue it all together.

But what if the appliance you want to control doesn’t use a common frequency? That’s a question that [eigma] recently had to answer after finding the remote control for the bedroom ceiling fan was operating at a somewhat unusual 304 MHz. Something like the MAX1472 could probably have been tuned to this frequency, but the chip doesn’t seem to be available in a turn-key module as the popular 315 MHz transmitters are.

There were a few possible options, including using a software defined radio (SDR), but [eigma] didn’t want to spend a fortune on this project or wait months for parts to get shipped from overseas. The most straightforward solution was to design a custom transmitter tuned to the proper frequency using discrete components; something of a dark art to those of us who’ve been spoiled by the high availability of modular components.

What follows is an fascinating look at the design, testing, and troubleshooting of a truly scratch-built transmitter. You won’t find any ICs here, the carrier signal is generated with just a transistor, some carefully measured pieces of wire, and a handful of passive components. By modulating the signal with an ESP32, [eigma] successfully makes the oddball ceiling fan an honorary member of the Internet of Things.

The write-up that [eigma] has done is an absolutely invaluable resource if you ever find yourself in need of rolling a bespoke transmitter. It easily ranks among some of the most informative radio reverse engineering work we’ve covered, and you’d be wise to file this one away for future reference. That said, most of the newer hardware you’re going to run into will probably be utilizing a widely-supported frequency like 433 MHz.

April 30, 2020 at 10:00PM
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An All Lead Screw 3D Printer You Can Build Yourself

An All Lead Screw 3D Printer You Can Build Yourself
By Jenny List

There was a time when the curious hardware hacker  had to build their own 3D printer, because commercial models were so expensive as to be unaffordable except by well-funded institutions. We’re fortunate then to live in an era in which a good quality off-the-shelf machine can be had without breaking the bank, but that is not to say that home-made 3D printers are a thing of the past. Instead the community of rapid prototyping experimenters continue to push the boundaries of the art, and from that we all benefit. An example comes from [Morgan Lowe], whose 3DLS lead screw driven 3D printer joins the freely downloadable designs to be found on Thingiverse.

If at first sight you think it looks a little familiar, you are correct, as it takes its frame design from the popular AM8 metal frame upgrade for the Anet A8 off-the-shelf printer. It draws heavily from other A8 upgrades, and brings in some parts such as the extruder and bed from the Creality Ender3. This is the beauty of incremental open source, and the result is a belt-free printer that does a decent-looking Benchy on the bench, and as a party piece manages to print a slightly more hairy little plastic boat when suspended at 45 degrees by a rope from the ceiling.

When dipping a toe into the world of home made 3D printers it’s interesting to take a look into some of the earlier Hackaday RepRap posts, and see how far we’ve come.

April 30, 2020 at 08:30PM
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New Contest: Making Tech at Home

New Contest: Making Tech at Home
By Mike Szczys

Put that parts bin to good use and build something! That’s the gist of the Making Tech at Home contest where your inner pack rat can shine by building from the parts you have on hand.

So what are you supposed to build? We’re not particular, we just want it to be cool. Grab everyone’s attention with an awesome project, and then win our hearts with the story of where you found the components.

Daniel Domínguez’s Parts Bin Self Portrait is an excellent example

An excellent example is the Parts Bin Self Portrait seen here that was a runner-up in the Circuit Sculpture contest. [Daniel Domínguez] talks about cutting out his silhouette from a scrap of prototyping board, pulling dev boards out of the parts box, and finding a ceiling fan on the side of the road which ended up donating the wire from the windings of its motor.

Your story is what’s important here. You can build a sleek and beautiful bit of gear that doesn’t look hacky at all — tell us about what the finished project does, but we also need to hear what parts you had on hand, where they came from, and what led you to use them. There is an element of satisfaction when that broken thermostat that you’ve been squirreling way for ten years, or the accidentally ordered reel of 0402 resistors, ends up getting used. Dust off that electronics hoard and get building!

Prizes Sent Out Throughout the Contest

This contest runs until July 28th, but you won’t have to wait that long to score some loot. Thirty entries will win a grab bag of stuff from Digi-Key and we’ll pick a few projects every week as we work toward that number. Help us decide what to send in those grab bags by voting for the gear you like the most.

Once the contest wraps up, three top winners will receive a mega grab bag stuffed with $500 worth of components. You know… to add to your parts bin for all those future builds.

If you’re anything like us, people deliver their broken stuff to you because they’ve heard you build things out of broken electronics. You feel torn about keeping old hardware around, but feel guilty about sending it to the landfill. When you order parts you get multiples just so you have them on hand for the next project. You were made for this competition, and no matter who the prizes go to, we want a look inside your parts bin.

April 30, 2020 at 06:01PM
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Raspberry Pi Gets High Quality Camera Upgrade

Raspberry Pi Gets High Quality Camera Upgrade
By Caleb Kraft

I knew a lot of people that got excited when the original raspberry pi camera was announced, but quickly found themselves limited by the quality of the image. It can be really great to have that much control behind the sensor, but frustrating when your results are always a bit […]

Read more on MAKE

The post Raspberry Pi Gets High Quality Camera Upgrade appeared first on Make: DIY Projects and Ideas for Makers.

April 30, 2020 at 06:03PM
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This Animatronic Mouth Mimics Speech With Servos

This Animatronic Mouth Mimics Speech With Servos
By Dan Maloney

Of the 43 muscles that comprise the human face, only a few are actually important to speaking. And yet replicating the movements of the mouth by mechanical means always seems to end up only partly convincing. Servos and linkages can only approximate the complex motions the lips, cheeks, jaw, and tongue are capable of. Still, there are animatronics out there that make a good go at the job, of which this somewhat creepy mechanical mouth is a fine example.

Why exactly [Will Cogley] felt the need to build a mechanical maw with terrifying and fairly realistic fangs is anyone’s guess. Recalling his lifelike disembodied animatronic heart build, it just seems like he pursues these builds for the challenge of it all. But if you thought the linkages of the heart were complex, wait till you see what’s needed to make this mouth move realistically. [Will] has stuffed this pie hole with nine servos, all working together to move the jaw up and down, push and pull the corners of the mouth, raise and lower the lips, and bounce the tongue around.

It all seems very complex, but [Will] explains that he actually simplified the mechanical design to concentrate more on the software side, which is a text-to-speech movement translator. Text input is translated to phonemes, each of which corresponds to a mouth shape that the servos can create. It’s pretty realistic although somewhat disturbing, especially when the mouth is placed in an otherwise cuddly stuffed bear that serenades you from the nightstand; check out the second video below for that.

[Will] has been doing a bang-up job on animatronics lately, from 3D-printed eyeballs to dexterous mechatronic hands. We’re looking forward to whatever he comes up with next — we think.

 

April 30, 2020 at 05:00PM
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3D Printering: Will A Resin Printer Retire Your Filament-based One?

3D Printering: Will A Resin Printer Retire Your Filament-based One?
By Donald Papp

Adding a resin printer to one’s workbench has never looked so attractive, nor been so affordable. Complex shapes with effortlessly great detail and surface finish? Yes, please! Well, photos make the results look effortless, anyway. Since filament-based printers using fused deposition modeling (FDM) get solid “could be better” ratings when it comes to surface finish and small detail resolution, will a trusty FDM printer end up retired if one buys a resin printer?

The short answer is this: for users who already use FDM, a resin-based stereolithography (SLA) printer is not likely to take over. What is more likely to happen is that the filament printer continues to do the same jobs it is good at, while the resin printer opens some wonderful new doors. This is partly because those great SLA prints will come at a cost that may not always justify the extra work.

Let’s go through what makes SLA good, what it needs in return, and how it does and doesn’t fit in with FDM.

When SLA Is Good, It’s REALLY Good

Objects with organic curves and no real “up” or “down” are much better suited to SLA than FDM.

The sweet spot for resin printing is this: small objects with smooth finishes, organic curves, and surface details. With SLA, these objects print more reliably and at a consistently higher quality than with FDM — as long as the operator does a good job with layout and support placement, anyway.

A big reason for this is that SLA does not produce layer lines the way FDM does. FDM prints are notorious for visible layer lines, and those lines are at their worst when spread across curved surfaces. SLA still creates objects one layer at a time, but the process doesn’t leave obvious lines.

There is also more freedom in part orientation when printing in resin. Unlike FDM, resin prints are isotropic. In the context of 3D printing, this means that the printed object’s physical properties do not change with respect to physical orientation. As long as a part is supported enough to print properly, a resin printer doesn’t much care in which orientation or at what angle it builds an object; the result will come out the same. This gives SLA printers more flexibility when it comes to part orientation, which helps when trying to keep presentation surfaces and details free from supports.

Niche Applications for SLA’s Strengths

One example of a niche for what resin printing is good at is gaming miniatures and figures. Tabletop enthusiasts are buying printers and resin, and designers of gaming-related models are finding success as well. The more successful ones thrive on sites like Patreon, with thousands of monthly supporters.

Engineering applications can have a place with SLA, so long as the objects are small enough. The build volume of most SLA printers is revoltingly tiny compared to FDM, but they make up for it with the ability to handle shapes and details that FDM would have problems with.

Beware SLA’s Added Costs

SLA printing brings some annoying buddies everywhere it goes in the form of added costs. These aren’t costs for the machines themselves; hobbyist SLA printers are very affordable. These ongoing costs are for consumables, increased time for upkeep and part processing, and storage space.

SLA requires more setup and cleanup than FDM. Printed parts need to be washed (usually in an alcohol bath) after printing, and possibly post-cured with additional UV exposure. Since resin is messy, disposable gloves and a spill-resistant work area are required. Another thing to consider is that resin isn’t meant to be left sitting in a printer for long periods, so when printing is done for the forseeable future, it’s time to empty the printer and clean the parts.

All of this takes time, but it also takes up valuable space in a work area. Bottles of resin, containers of alcohol, wash bins, gloves, a drip-proof work space, all of it takes up storage and table space. SLA printing as a whole will take up far more room than just the printer itself.

The other thing to consider is the need for manual post-processing. Resin prints tend to require a lot of supports, and those supports need to be removed by hand. These leave behind small marks that may need to be sanded away. With FDM, supports are a last resort that are used only if needed, but with SLA they are the rule rather than the exception.

Things FDM Is Still Good At

A well-maintained FDM printer is a fantastic tool for prototyping, iterating on designs, and creating functional parts. FDM also has other advantages that really stand out when contrasted with resin printing.

FDM is perfectly happy to wait patiently until needed, at which point a print can be started with a minimum of fuss. The consumables are few and reasonably priced. Filament is best stored in a dry environment, but besides that, it doesn’t ask for much. Swapping filament types or colors is simple, clean, and easy. Even a failed print doesn’t usually involve much more than sweeping away a mess of plastic and trying again.

The biggest disadvantages are related to layer line visibility, the resolution of surface detail, and working with curved organic shapes. None of these can be waved away, but they can be mitigated to some extent. Variable Layer Height tries to address layer line visibility, and it is a feature that has worked its way into most slicer software. The ability to render very small details and features can be improved, to some extent, by swapping a printer’s standard 0.4 mm nozzle for a smaller one.

FDM printers are most challenged by being asked to print curved objects that have no flat areas and no real “up” or “down”. One option is splitting these objects into smaller and more easily-printed ones, but that’s not always practical. Printing a tricky model will require supports, and supports with FDM always result in degraded surface quality. Water-soluble support structures can help mitigate this, but doing so requires multi-material printing. SLA, on the other hand, is far more suited to such objects.

Is There Room for Both?

Resin prints look fantastic and it may be tempting to think of SLA as superior to FDM, but that is not the whole story. They are different tools, and good at different things. Unless your needs are very specific, you’ll probably benefit from access to both.

If you need to print small objects with good surface finish and detail resolution, and you can deal with the added hassles of working with resin, then SLA is definitely for you. But even if you only print small objects, a working FDM printer can easily earn its place on your workbench with the ability to create functional parts without any significant setup and cleanup. If you’re considering an SLA printer, don’t plan to ditch FDM just yet.

I regularly use both but personally, I always choose a filament-based printer if possible; even if a final model will eventually be printed in resin, it’s simply cheaper and faster and easier to prototype and iterate with FDM.

If you have access to both, has this also been your experience? Do you know of a niche for resin printing that hits the spot in a way nothing else does, the way SLA has done with tabletop enthusiasts? We want to hear all about it, so let us know in the comments.

April 30, 2020 at 04:00PM
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Giving Surfaces Their Own Antiviral Coating To Fight Infection

Giving Surfaces Their Own Antiviral Coating To Fight Infection
By Maya Posch

The use of disinfectants is not a new thing, but a major disadvantage with most common disinfectants is that they are only effective in the short term. After applying bleach, alcohol or other disinfectant to the surface, the disinfectant’s effect quickly fades as the liquid evaporates. Ideally the disinfectant would remain on the surface, ready to disinfect when needed.

According to researchers at the Hong Kong University of Science and Technology (HKUST), the solution may lie in a heat-sensitive coating that releases disinfectant when it’s needed. This Multilevel Antimicrobial Polymer (MAP-1) can remain effective for as long as 90 days, depending on how often the surface is touched or otherwise used.

MAP-1 consists out of polymer strands of a material that prevents viruses and bacteria from attaching to its surface, while disrupting its outside surface. Effectively this has the potential to inactivate (kill) most viruses and harmful bacteria that come into contact with it.

MAP-1 is currently being deployed in Hong Kong, where public places such as schools, malls and sport facilities have had the coating applied. It costs between US $2,600 and US $50,000 to treat an area, which is not cheap, but would be cheaper than shutting down such a facility for regular surface disinfecting.

Although it still has to be determined that MAP-1 is as effective as hoped, it is another example of an antimicrobial surface, a material that is designed to be as incompatible with sustaining viruses and bacteria as possible. In the past copper and its alloys have been commonly used for this purpose, but a polymer coating is obviously more versatile. From the point of view of today’s pandemic, making surfaces incapable of hosting viruses definitely can be regarded as highly necessary.

(Pictured: a MAP-1 coating on a surface, courtesy of HKUST)

April 30, 2020 at 01:00PM
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