New Tech And The Old Ways

April 30, 2022 by 8 Comments

This week on Hackaday, we featured a project that tickled my nostalgia bone, and proved that there are cool opportunities when bringing new tech to old problems. Let me explain.

[Muth] shared a project with us that combines old-school analog photography printing with modern LCD screens. The basic idea is to use a 4K monochrome screen in place of a negative, making a contact print by placing the screen directly on top of photographic paper and exposing it under a uniform light source. Just like the old ways, but with an LCD instead of film.

LCD exposure animationBut what’s the main difference between a screen and film? You can change the image on the LCD at will, of course. So when [Muth] was calibrating out exposures, it dawned on him that he could create a dynamic, animated version of his image and progressively expose different portions of the paper, extending the available dynamic range and providing him the ability to control the slightest nuances of the resulting image contrast.

As an old photo geek, this is the sort of trick that we would pull off manually in the darkroom all the time. “Dodging” would lighten up a section of the image by covering up the projected light with your hand or a special tool for a part of the exposure time. With [Muth]’s procedure, he can dodge the image programmatically on the per-pixel level. We would have killed for this ability back in the day.

The larger story here is that by trying something out of the box, applying a new tool to an old procedure, [Muth] stumbled on new capabilities. As hackers, we’re playing around with the newest tech we can get our hands on all the time. When you are, it might be that you also stumble on new possibilities simply afforded by new tech. Keep your eyes open!

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Training Doppler Radar With Smart Watch IMUs Data For Activity Recognition

April 30, 2022 by 3 Comments

When it comes to interpreting sensor data automatically, it helps to have a large data set to assist in validating it, as well as training when it concerns machine learning (ML). Creating this data set with carefully tagged and categorized information is a long and tedious process, which is where the idea of cross-domain translations come into play, as in the case of using millimeter wave (mmWave) radar sensors to recognize activity of e.g. building occupants with the IMU2Doppler project at Smash Lab of Carnegie Mellon University.

The most commonly used sensor type when it comes to classifying especially human motion are inertial measurement units (IMU) such as accelerometers and gyroscopes, which are found in everything from smartphones to smart watches and fitness bands. For these devices it’s common to classify measurement patterns as matches a particular activity, such as walking, jogging, or brushing one’s teeth. This makes them both well-defined and very accessible.

As for why a mmWave-based Doppler radar would be preferred for monitoring e.g. building occupants is the privacy aspect compared to using cameras, and the inconvenience of equipping people with a body-worn IMU. Using Doppler radar it would theoretically be possible for people to track activities within their own home, as well as in a medical setting to ensure patients are safe, or at a gym to track one’s performance, or usage of equipment. All without the use of cameras or personal sensors. In the past, we’ve seen a similar approach that used targeted laser beams.

As promising as this sounds, at this point in time the number of activities that are recognized with reasonable accuracy (~70%) is limited to ten types. Depending on the intended application this may already be sufficient, though as the published paper notes, there is still a lot of room for growth.

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The laser module shown cutting shapes out of a piece of cardboard that's lying on the CNC's work surface

Giant CNC Partners With Powerful Laser Diode

April 30, 2022 by 13 Comments

[Jeshua Lacock] from 3DTOPO owns a large-format CNC (4’x8′, or 1.2×2.4 m), that he strongly feels is lacking laser-cutting capabilities. The frame is there, and a 150 W CO2 laser tube has been sitting in a box for ages – what else could you need? Sadly, at such a scale, aligning the mirrors is a tough and finicky job – and misalignment can be literally blinding. After reading tales about cutters of such size going out of alignment when someone as much as walked nearby, he dropped the idea – and equipped the CNC head with a high-power laser diode module instead. Having done mirror adjustment on a few CO2 tube-equipped lasers, we can see where he’s coming from.

Typically, the laser modules you see bolted onto CNC heads are firmly under three watts, which is usually only enough for engraving. With a module that provides 5 watts of optical power, [Jeshua] can cut cardboard and thin plywood as well he tells us even 10 W optical power modules are available, just that he didn’t go for one. We reckon that 20 W effective power diodes are not that far into our future, which is getting very close to the potential of the blue box “40 W but actually 35 W but actually way less” K40 laser cutters we cherish. [Jeshua]’s cutter is not breaking speed limits, but it’s built on what’s already there, and the diode is comparatively inexpensive. Equipped with a small honeycomb surface and what seems to be air assist, it’s shown in the video cutting an ornamental piece out of cardboard!

We hackers have been equipping CNCs with laser diodes for a while, but on a way smaller scale and with less powerful diodes – this is definitely a step up! As a hacker, you should have at least some laser cutting options at your disposal, and this overview of CO2 cutters and their availability can get you started. We’ve also given you detailed breakdowns about different sides of laser cutting, be it the must-have of safety, or the nice-to-have of air assist.

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A Great Resource For The Would-Be Pinball Machine Builder

April 29, 2022 by 12 Comments

Those of us beyond a certain age will very likely have some fond memories of many an hour spent and pocket money devoured feeding the local arcade pinball machine. At one time they seemed to be pretty much everywhere, but sadly, these days they seem to have largely fallen out of favour and are becoming more of speciality to be specifically sought out. Apart from a few random ones turning up — there’s a fun Frankenstein-themed machine in the Mary Shelley Museum in Bath, England — a trip to a local amusement arcade is often pretty disappointing, with modern arcade machines just not quite scratching that itch anymore, if you ask us. So what’s an old-school hacker to do, but learn how to build a machine from scratch, just the way we want it? A great resource for this is the excellent Pinball Makers site, which shows quite a few different platforms to build upon and a whole ton of resources and guides to help you along the way.

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Arduino And Git: Two Views

April 29, 2022 by 16 Comments

You can’t do much development without running into Git, the version control management system. Part of that is because so much code lives on GitHub which uses Git, although you don’t need to know anything about that if all you want to do is download code. [Dr. Torq] has a good primer on using Git with the Arduino IDE, if you need to get your toes wet.

You might think if you develop by yourself you don’t need something like Git. However, using a version control system is a great convenience, especially if you use it correctly. There’s a bug out in the field? What version of the firmware? You can immediately get a copy of the source code at that point in time using Git. A feature is broken? It is very easy to see exactly what changed. So even if you don’t work in a team, there are advantages to having source code under control.

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Motorcycle Voltage Regulator Uses MOSFETs

April 29, 2022 by 34 Comments

For how common motorcycles are, the designs and parts used in them tend to vary much more wildly than in cars and trucks. Sometimes this is to the rider’s advantage, like Honda experimenting with airbags or automatic transmissions. Sometimes it’s a little more questionable, like certain American brands holding on to pushrod engine designs from the ’40s. And sometimes it’s just annoying, like the use of cheap voltage regulators that fail often and perform poorly. [fvfilippetti] was tired of dealing with this on his motorcycle, so he built a custom voltage regulator using MOSFETs instead.

Unlike a modern car alternator, which can generate usable voltage even at idle, smaller or older motorcycle alternators often can’t. Instead they rely on a simpler but less reliable regulator that is typically no more than a series of diodes, but which can only deliver energy to the electrical system while the motor is running at higher speeds. Hoping to improve on this design, [fvfilippetti] designed a switched regulator from scratch out of MOSFETs with some interesting design considerations. It is capable of taking an input voltage between 20V and 250V, and improves the ability of the motorcycle to use modern, higher-power lights and to charge devices like phones as well.

In the video below, an LED was added in the circuit to give a visual indication that the regulator is operating properly. It’s certainly a welcome build for anyone who has ever dealt with rectifier- or diode-style regulators on older bikes before. Vehicle alternators are interesting beasts in their own right, too, and they can be used for much more than running your motorcycle’s electrical system.

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ITman496 in his ATV, using the trashcan lifter to lift a trashcan up in the air. The lifter is a contraption mounted to the front of his ATV, welded together with square tubing

Equipping An ATV With A Trashcan Lifter

April 29, 2022 by 6 Comments

[ITman496] is one of us hackers working his way around health problems, in his case, a back injury. He is eager to solve various difficulties he has to deal with, and in case of the video he made, it was about moving a large trashcan through ice-covered roads on his property. Not willing to risk his health any further and dissatisfied with the flimsy solutions for sale requiring him to do the heavy lifting, still, he designed and built a winch-powered trashcan lifter mechanism – not entirely unlike a forklift. He mounted it to his ATV, tested it, improved upon it, filming his progress along the way – and then made a video detailing the entire build for us!

Having sketched the concept on his phone, he modeled and tested it in SketchUp, then cut and welded the parts, describing a welding alignment trick along the way – using 3D-printed joints to hold the two parts-to-be-welded together for tack welds, ensuring nigh-perfect alignment. Initial testing was a success! From there, he describes a good few surprising but in retrospect expected ease-of-use improvements that didn’t crop up during simulations, like adding chamfers to the scoop, so that he doesn’t have to angle his ATV super precisely to pick the trashcan up. In the end, having used it for about a month now, he tells us it’s been working extremely well for his purposes!

Not all such garbage cans need to be taken out, thankfully – some of them go voluntarily, and you can even get smaller ones that catch stuff you throw from across the room. We’ve covered the adventures of [ITman496] before, learning lessons from a failed robot build in 2016., and adopting an ultralight plane in 2018!

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