EcoEDA Integrates Your Junk Bin Into Your Designs

If you’re like us, there’s a creeping feeling that comes over you when you’re placing an order for parts for your latest project: Don’t I already have most of this stuff? With the well-stocked junk bins most of us sport and the stacks of defunct electronics that are almost always within arm’s length, chances are pretty good you do. And yet, we always seem to just click the button and place a new order anyway; it’s just easier.

But what if mining the treasure in your junk bin was easier? If you knew right at design time that you had something in your stash you could slot into your build, that would be something, right? That’s the idea behind ecoEDA, a Python-based KiCAD plugin by [Jasmine Lu], [Beza Desta], and [Joyce Passananti]. The tool integrates right into the schematic editor of KiCAD and makes suggestions for substitutions as you work. The substitutions are based on a custom library of components you have on hand, either from salvaged gear or from previous projects. The plug-in can make pin-for-pin substitutions, suggest replacements with similar specs but different pinouts, or even build up the equivalent of an integrated circuit from available discrete components. The video below gives an overview of the tool and how it integrates into the design workflow; there’s also a paper (PDF) with much more detail.

This seems like an absolutely fantastic idea. Granted, developing the library of parts inside all the stuff in a typical junk bin is likely the biggest barrier to entry for something like this, and may be too daunting for some of us. But there’s gold in all that junk, both literally and figuratively, and putting it to use instead of dumping it in a landfill just makes good financial and environmental sense. We’re already awash in e-waste, and anything we can do to make that even just a little bit better is probably worth a little extra effort. Continue reading “EcoEDA Integrates Your Junk Bin Into Your Designs”

USB-C For Hackers: Build Your Own PSU

What if you wanted to build your own USB-C PSU? Good news – it’s easy enough! If you ever wanted to retrofit a decent DC PSU of yours to the USB-C standard, say, you got a Lenovo/HP/Dell 19V-20V charger brick and you’ve ever wished it were USB-C, today is the day when we do exactly that. To be fair, we will cheat a bit – but only a tiny bit, we won’t be deviating too much from the specification! And, to begin with, I’ll show you some exceptionally easy ways that you can turn your DC PSU into a USB-C compatible one, with a simple module or a few.

Turning a 20 V PSU into a USB-C PSU feels natural if you want to charge a laptop – those tend to request 20 V from a USB-C PSU anyway, so what’s the big deal? However, you can’t just put 20 V onto a USB-C connector – you have to add a fair bit of extra logic to make your newly christened USB-C PSU safe to use with 5 V devices, and this logic also requires you go through a few extra steps before 20 V appears on VBUS. Any USB-C PSU has to output 5 V first and foremost whenever a device is connected, up until a higher voltage is negotiated digitally, and the PSU may only switch to a higher voltage output when it’s requested to do so.

Now, for that, a PSU offers a list of profiles, and we looked into those profiles in the Replying PD article – each profile is four bytes that contain information about the profile voltage, maximum current that the device may draw at that voltage, and a few other details. For a PSU to be USB-C compliant, the USB-C specification says that, in addition to 5 V, you may also offer 9 V, 15 V, and 20 V.

Also, the specification says that if a PSU supports certain in-spec voltage like 15 V, it’s also required by the spec to offer all of the spec-defined voltages below the maximum one – for 15 V, that also requires supporting 9 V. Both of these are UX requirements, as opposed to technical requirements – it’s easier for device and PSU manufacturers to work with a small set of pre-defined voltages that majority of the chargers will support, but in reality, you can actually offer any voltage you want in the PSU advertisement; at worst, a device is going to refuse and contend with slowly charging from the 5 V output that you’re required to produce.

I’d like to walk you through how off-the-shelf USB-C PSUs work, all of the options you can use to to create one, and then, let’s build our own USB-C PSU from scratch! Continue reading “USB-C For Hackers: Build Your Own PSU”

Multi-Year Doorbell Project

Camera modules for the Raspberry Pi became available shortly after its release in the early ’10s. Since then there has been about a decade of projects eschewing traditional USB webcams in favor of this more affordable, versatile option. Despite the amount of time available there are still some hurdles to overcome, and [Esser50k] has some supporting software to drive a smart doorbell which helps to solve some of them.

One of the major obstacles to using the Pi camera module is that it can only be used by one process at a time. The PiChameleon software that [Esser50k] built is a clever workaround for this, which runs the camera as a service and allows for more flexibility in using the camera. He uses it in the latest iteration of a smart doorbell and intercom system, which uses a Pi Zero in the outdoor unit armed with motion detection to alert him to visitors, and another Raspberry Pi inside with a touch screen that serves as an interface for the whole system.

The entire build process over the past few years was rife with learning opportunities, including technical design problems as well as experiencing plenty of user errors that caused failures as well. Some extra features have been added to this that enhance the experience as well, such as automatically talking to strangers passing by. There are other unique ways of using machine learning on doorbells too, like this one that listens for a traditional doorbell sound and then alerts its user.

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Weather Station With Distributed Sensors

Building a weather station is a fairly common project that plenty of us have taken on, and for good reason. They can be built around virtually any microcontroller or full-scale computer, can have as many or few sensors as needed, and range from simple, straightforward projects to more complex systems capable of doing things like sending data off to weather services like Weather Underground. This weather station features a few innovations we don’t often see, though, with a modular and wireless design that makes it versatile and easy to scale up or down as needed.

Each of the modules in this build use the ESP32 platform, which simplifies design and also takes care of the wireless capability needed. The base station gets a few extra sensors including those for carbon dioxide, volatile organic compounds, and nitrogen oxides. It also includes a screen which can be used to display a wide variety of data gathered locally but also includes forecast information fetched from the free OpenWeatherMap API. For the sensor modules, BME280 sensors are used for temperature, pressure, and humidity and each module includes its own solar panel and battery with the ESP32 chips set to operate using as little energy as possible.

One of the things that helps easily integrate all of the sensor modules is the use of ESP-NOW, which we have seen a few times before. It essentially eliminates the need for a router and allows ESP modules to connect directly with one another. The build also goes into detail about most of the aspects of this project including the programming of the GUI that the ESP32 base station displays on its screen, so for anyone looking to start their own weather station project this should be an excellent guide. Make sure to check out this one as well if you want to send all of your weather data to Weather Underground.

Better 3D Prints, Courtesy Of A Simple Mass-Produced Bracket

On the “hack/not-a-hack” scale, a 3D printed bracket for aluminum extrusions is — well, a little boring. Such connectors are nothing you couldn’t buy, and even if you insisted on printing them instead, Printables and Thingiverse are full of ready-to-use designs. So why would you waste your precious time and effort rolling your own?

According to production 3D printing company [Slant 3D], a lot of times, we forget to take advantage of the special capabilities of 3D printing. The design progression of the L-bracket shown is a perfect example; it starts as a simple L, moves on to a more elaborate gusseted design, and eventually into a sturdy sold block design that would be difficult to make with injection molding thanks to shrinkage but is no problem for a 3D printer. Taking that a step further, the bracket morphs into a socketed design, taking advantage of what 3D printers can do by coming up with a part that reduces assembly time and fastener count while making a more finished, professional look.

Again, this isn’t really about the bracket. Rather, it’s about a different way of thinking about your designs and leveraging the unique capabilities of 3D printers relative to other mass-production methods, like injection molding. We’ve covered some of [Slant 3D]’s high-volume design insights before, such as including living hinges and alternatives of pins and holes for assembling printed parts. Continue reading “Better 3D Prints, Courtesy Of A Simple Mass-Produced Bracket”

Trebuchet Sends Eggs Flying

Without any sort of restrictions on designs for trebuchets, these medieval siege weapons are known to send 90 kilogram projectiles over 300 meters. The egg-launching trebuchet contest that [AndysMachines] is entering, on the other hand, has a few limitations that dramatically decreased the size of the machines involved. The weight of the entire device is limited to no more than 3 kg, with any physical dimension no more than 300 mm, but that’s more than enough to send an egg flying across a yard with the proper design and tuning for maximum distance.

Trebuchets distinguish themselves amongst other siege weapons by using a falling weight to launch the projectile. The rules of this contest allow for the use of springs, so [AndysMachines] is adding a spring in between the trebuchet arm and the weight in order to more efficiently deliver the energy from the falling weight. More fine tuning of the trebuchet was needed before the competition, though, specifically regarding the stall point for the trebuchet. This is the point where the forces acting on the arm from the projectile and the weight are balanced, and moving this point to allow the projectile to release at a 45-degree angle was needed for maximum distance.

The video goes into a lot of detail about other fine-tuning of a trebuchet like this, aided by some slow-motion video analysis. In the end, [AndysMachines] was able to launch the egg over ten meters with this design. Of course, if you want to throw out the rule book and replace the eggs with ball bearings and the aluminum and steel with titanium, it’s possible to build a trebuchet that breaks the sound barrier.

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Using FreeCAD To Replace OEM Parts

As much as we might all like it if manufacturers supported their products indefinitely with software updates or replacement parts, this just isn’t feasible. Companies fail or get traded, technologies evolve, and there’s also an economic argument against creating parts for things that are extremely old or weren’t popular in the first place. So, for something like restoring an old car, you might have to resort to fabricating replacement parts for your build on your own. [MangoJelly] shows us how to build our own replacement parts in FreeCAD in this series of videos.

The build does assume that the original drawings or specifications for the part are still available, but with those in hand FreeCAD is capable of importing them and then the model scaling to match the original specs shown. This video goes about recreating a hinge on an old truck, so with the drawings in hand the part is essentially traced out using the software, eventually expanding it into all three dimensions using all of the tools available in FreeCAD. One of the keys to FreeCAD is the various workbenches available that all have their own sets of tools, and being able to navigate between them is key to a build like this.

FreeCAD itself is an excellent tool for anyone repairing old vehicles like this or those making 3D prints, designing floorplans for houses, or really anything you might need to model in a computer before bringing the idea into reality. It does have a steep learning curve (not unlike other CAD software) so it helps to have a video series like this if you’re only just getting started or looking to further hone your design skills, but the fact that it’s free and open-source make it extremely attractive compared to its competitors.

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