A slide carousel with a DSLR attached to its lens output

Digitize Your Slide Deck With This Arduino-Powered Slide Carousel

If you’re above a certain age, you probably remember the atmosphere of a pre-Powerpoint 35 mm slide show. The wobbly screen being unrolled, the darkened room, the soft hum of the projector’s fan, the slightly grainy picture on the screen and that unmistakable click-whoosh-clack sound as the projector loaded the next slide. Nowadays you’ll be hard pressed to find anyone willing to set up a screen and darken the room just to watch a few photos, so if you still have any slides lying around you’ll probably want to digitize them. If you’ve also kept your projector then this doesn’t even have to be that difficult, as [Scott Lawrence] shows in his latest project.

[Scott] made a setup to directly connect a DLSR, in this case a Nikon D70, to a Kodak 760 slide carousel. The attachment is made through a 3D-printed adapter that fits onto the Nikon’s macro lens on one side and slides snugly into the carousel’s lens slot on the other. The adapter also holds an IR transmitter which is aimed at the camera’s receiver, in order to trigger its remote shutter release function.

The carousel’s original light source was replaced with a compact LED studio light, which allows for precise brightness control and of course remains nice and cool compared to the original incandescent bulb. The light, camera and carousel motor are all controlled through a central user interface driven by an Arduino Leonardo which can automatically advance the carousel and instruct the camera to take a picture, thereby taking the hard work out of digitizing huge stacks of slides.

[Scott] plans to make the software and STL files available on GitHub soon, so anyone can go ahead and turn their projector into a digitizer. If you’ve misplaced your projector however, a simple 3D-printed slide adapter for your camera also works for small slide decks.

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A two picture montage with the left montage showing a pair of hands holding an assembled and closed turbidity sensor and the right picture showing A pair of hands holding the screw on cap for the turbidity sensor and a prototype board against a backdrop of green leave

Rapid Prototyping To Measure Turbidity In Rapids

[RiverTechJess] is in the process of getting a PhD in environmental engineering and has devoted a chapter to creating a turbidity sensor for river network monitoring. Environmental sensing benefits from being able to measure accurately and frequently, so providing low cost devices helps get more data and excuse the occasional device loss that’s bound to happen when deploying electronics out in the wild. Towards this end, [RiverTechJess] has created a low cost turbidity sensor that rivals the more expensive alternatives in cost and accuracy.

The turbidity sensor is designed to be at least partially submerged allowing for the LED and light sensors to be be able to take measurements. [RiverTechJess] has made a 3D printed prototype to test the design, allowing for rapid experimentation and deployment of the sensors to work out issues. The 3D printed enclosure prototype uses rubber o-rings and “vacuum grease” to provide a watertight seal. An ESP32 microcontroller is used to store logged data on an SD card and drive the TSHG6200 850nm infrared LED and the two TSL237S-LF sensors.

The resulting paper on the turbidity sensor, in addition to the blogs of the process, provide a wealth of data that show what goes into developing and calibrating a device that is meant to be used for environmental monitoring. All source code is available on GitHub and development continues on a newer revision of the turbidity sensor with updated electronics and hardware.

We’re no strangers to water sensors and we’ve seen devices from internet connected water pollution monitors to small handheld potable water detectors.

Video after the break!

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Wearable Sensor Trained To Count Coughs

There are plenty of problems that are easy for humans to solve, but are almost impossibly difficult for computers. Even though it seems that with modern computing power being what it is we should be able to solve a lot of these problems, things like identifying objects in images remains fairly difficult. Similarly, identifying specific sounds within audio samples remains problematic, and as [Eivind] found, is holding up a lot of medical research to boot. To solve one specific problem he created a system for counting coughs of medical patients.

This was built with the idea of helping people with chronic obstructive pulmonary disease (COPD). Most of the existing methods for studying the disease and treating patients with it involves manually counting the number of coughs on an audio recording. While there are some software solutions to this problem to save some time, this device seeks to identify coughs in real time as they happen. It does this by training a model using tinyML to identify coughs and reject cough-like sounds. Everything runs on an Arduino Nano with BLE for communication.

While the only data the model has been trained on are sounds from [Eivind], the existing prototypes do seem to show promise. With more sound data this could be a powerful tool for patients with this disease. And, even though this uses machine learning on a small platform, we have seen before that Arudinos are plenty capable of being effective machine learning solutions with the right tools on board.

Getting To The Heart Of A Baofeng

In amateur radio circles, almost no single piece of equipment serves as more of a magnet for controversy than the humble Baofeng handheld transceiver. It’s understandable — the radio is a shining example of value engineering, with just enough parts to its job while staying just on the edge of FCC rules. And at about $25 a pop, the radios are cheap enough that experimentation is practically a requirement of ownership.

But stripped down as the Baofeng may be, it holds secrets inside that are even more tempting to play with than the radio itself. And who better than [HB9BLA], a guy who has a suspiciously familiar Swiss accent, to guide us through the RF module at the heart of the Baofeng, the SA818. For about $8 you can get one of these little marvels off AliExpress and have nearly all the important parts of a VHF or UHF radio — an SDR transceiver, a power amp, and all the glue logic to make it work.

In the video below, [Andreas] puts the SA818 module through its paces with the help of a board that pairs the module with a few accessories, like an audio amp and a low-pass RF filter. With a Raspberry Pi and a Python library to control the module, it’s a decent imitation of the functionality of a Baofeng. But that’s only the beginning. By adding a USB sound card to the Pi, the setup was able to get into every ham’s favorite packet radio system, APRS. There are a ton of other applications for the SA818 modules, some of which [Andreas] mentions at the end of the video. Pocket-sized repeaters, a ridiculously small EchoLink hotspot, and even an AllStar node in an Altoids tin.

Of course, if you want to get in on the fun, you’re going to need an amateur radio license. Don’t worry, it’s easy — we’ll help you get there.

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Mastodon Comes To The IBM PC

Elon Musk has bought Twitter for an eye-watering sum, and his live adventures in chaotic mismanagement of a social media company have become a compelling performance for the rest of us. As we munch on our tasty popcorn and enjoy the show, many Twitter users have jumped ship for the open-source alternative Mastodon. It offers much to the escapee including instances tailored to particular communities, but aside from all that it’s got something Twitter never had. You can now use a Mastodon client on an IBM PC.

Many of you are no doubt looking askance at us, as you have been Tooting for years from behind the keyboard of a PC. But it’s likely that the PC you’re using is a generic modern x86 machine running an up-to-date operating system such as a GNU/Linux flavour or Microsoft Windows, by contrast here we’re referring to the original, the daddy of them all. Because the client we’re talking about is DOStodon, designed to run on a real IBM PC as though it’s the early 1980s again.

Stunt hacks aside, whether or not you fire up DOStodon on a 16-bit machine to get your Fediverse fix, it’s an interesting piece of software because it’s written in Javascript. Which in turn brings us to DOjS from the same author, a DOS Javascript canvas with sound. Not everyone will be raring to run their Javascript code on an early 1980s PC, but its existence proves that there’s plenty of life in the old platform yet.

Need more Mastodon on unexpected platforms? How about the ESP32?

Header image: Ruben de Rijcke, CC BY-SA 3.0, and Jin Nguyen, AGPL .

EV Sales Sticking Point: People Still Want Manual Transmissions

Call me crazy, but I’m ride or die for manual transmissions. I drove enough go-karts and played enough Pole Position as a kid to know that shifting the gears yourself is simply where it’s at when it comes to tooling around in anything that isn’t human-powered. After all, manuals can be roll-started. A driver has options other than braking and praying on slippery roads. Any sports car worth its rich Corinthian leather (or whatever) has a manual transmission, right? And you know that Rush’s Red Barchetta ain’t no automatic. Face it, shifting gears is just plain cooler. And it’s not a chore if it gets you more, although the fuel efficiency thing is a myth at this point.

You can imagine then my horror at the idea that someday within my lifetime, most cars will be twist-and-go electric go-karts. As the age of the combustion engine appears to draw to a close (no, seriously this time), there’s just one thing keeping the door open — marked enthusiasm for manual transmissions. From Audi to the Nissan Z, automakers report that the take rate for manual transmissions is quite high in the US, despite the death knell that has been tolling for two decades or so. Two models of Honda Civic are manual-only. This phenomenon isn’t restricted to sports cars, either — the 2022 Ford Bronco comes in a seven-speed manual, and has seen a take rate over 20%.

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Blender Builds LEGO Models

Blender is a free and open source computer graphics package that’s used in the production of everything from video games to feature films. Now, as demonstrated by [Joey Carlino], the popular program can even be used to convert models into LEGO.

This new feature available in Blender 3.4 allows for the use of instance attributes in a way that a large number of points on a model can be created without causing undue strain on (and possible crashing of) the software. Essentially, an existing model is split into discrete points at specific intervals. The spacing of the intervals is set to be exactly that of LEGO bricks, which gives the model the low-resolution look of a real LEGO set. From there, a model brick is created and placed at each of these points, and then colors can be transferred to the bricks individually.

The demonstration that [Joey] uses is converting a beach ball model to LEGO, but using these tools on other models delivers some striking results. He goes over a lot of the details on how to create these, and it would only be a short step from there to ordering the bricks themselves. Or, using these models and sending them over to a 3D printer straight from Blender itself. Not bad for free software!

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