Author: Dan Maloney

3373 Articles

Smart Outlet Cover Offers Lessons On Going From Project To Product

April 25, 2018 by 14 Comments

Going from idea to one-off widget is one thing; engineering the widget into a marketable product is quite another. So sometimes it’s instructive to take an in-depth look at a project that was designed from the get-go to be a consumer product, like this power indicating wall outlet cover plate. The fact that it’s a pretty cool project helps too.

Although [Vitaliy] has been working on this project for a while, he only recently tipped us off to it, and we’re glad he did because there’s a lot to learn here. His goal was to build a replacement cover for a standard North American power outlet that indicates how much power is being used by whatever is plugged into it. He set constraints that included having everything fit into the familiar outlet cover form factor, as well as to not require any modification to the existing outlet or rewiring, so that a consumer can just remove the old cover and put on the new one. Given the extremely limited space inside an outlet cover, these were significant challenges, but [Vitaliy] found a way. Current is sensed with two inductors positioned to sense magnetic flux within the outlet, amplified by a differential amp, and power use is calculated by an ATmega328 for display on 10 LEDs. Power for the electronics is tapped right from the outlet wiring terminals by spring clips, and everything fits neatly inside the cover.

It’s a great design, but not without issues. We look forward to seeing [Vitaliy] tackle those problems and bring this to market. For more on what it takes to turn a project into a product, check out our own [Lewin Day]’s story of bringing a guitar effects pedal to market.

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Temperature Sensor And Simple Oscillator Make A Value-Added HF Beacon

April 24, 2018 by 13 Comments

Sometimes the best projects are the simple, quick hits. Easily designed, fast to build, and bonus points for working right the first time. Such projects very often lead to bigger and better things, which appears to be where this low-power temperature beacon is heading.

In the world of ham radio, beacon stations are transmitters that generally operate unattended from a known location, usually at limited power (QRP). Intended for use by other hams to determine propagation conditions, most beacons just transmit the operator’s call sign, sometimes at varying power levels. Any ham that can receive the signal will know there’s a propagation path between the beacon and the receiver, which helps in making contacts. The beacon that [Dave Richards (AA7EE)] built is not a ham beacon, at least not yet; operating at 13.56 MHz, it takes advantage of FCC Part 15 regulations regarding low-power transmissions rather than the Part 97 rules for amateur radio. The circuit is very simple — a one-transistor Colpitts oscillator with no power amplifier, and thus very limited range. But as an added twist, the oscillator is keyed by an ATtiny13 hooked to an LM335 temperature sensor, sending out the Celsius and Fahrenheit temperature in Morse every 30 seconds or so. The circuit is executed in Manhattan style, which looks great and leaves plenty of room for expansion. [Dave] mentions adding a power amp and a low-pass filter to get rid of harmonics and make it legal in the ham bands.

Beacons are just one of the ways for hams to get on the air without talking. Another fun way to analyze propagation is WSPR, which is little like an IoT beacon.

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Tiny Vacuum Chamber Arm To Help With Homemade Semiconductors

April 23, 2018 by 13 Comments

[Nixie] wants to make semiconductors at home, and that requires some unusual tools. Chief among them is a vacuum chamber to perform thin-film deposition, and true to the hacker credo his is homemade, and will soon be equipped with a tiny manipulator arm with magnetically coupled mechanical controls.

If [Nixie]’s setup looks familiar, it might be because we featured his plasma experiments a few days ago. He was a little cagey then about his goal, but he’s come clean with his desire to make his own FETs (a project that is his 2018 Hackaday Prize entry). Doing so will require not only creating stable plasmas, but also the ability to move substrates around inside the vacuum chamber. Taking inspiration from the slender and maneuverable instruments surgeons use for laparoscopic procedures, [Nixie] is working on a miniature arm that will work inside his vacuum chamber. The video below is a 3D-printed proof-of-concept model in action, and shows how the arm’s segments will be controlled by cables. What’s really interesting is that the control cables will not penetrate the vacuum chamber — they’ll be moved right through the glass wall using magnets.

We’re keen to see chips from [Nixie]’s home fab lab, but it looks like there will be a lot of cool hacks between here and there. We’ll be watching closely. Continue reading “Tiny Vacuum Chamber Arm To Help With Homemade Semiconductors” →

Bargain Bin Barcode Scanner Keeps Track Of Shopping Needs

April 23, 2018 by 18 Comments

For most people, a Post-It note or dry-erase board suffices to ensure that household consumables are replenished when they’re used up. But hackers aren’t like most people, so this surplus barcode scanner turned kitchen inventory manager comes as little surprise. After all, if something is worth doing, it’s worth overdoing.

[Brian Carrigan]’s project began with a chance discovery of an old barcode scanner in his local scrap store. Questions as to why we can never find bargains like a $500 scanner for six bucks aside, [Brian] took the scanner home for a bit of reverse engineering. He knew it used RS-232 but it had been unceremoniously ripped from its connectors, so identifying pins took some detective work. With power and data worked out and the scanner talking to a Raspberry Pi, [Brian] set about integrating it into Wunderlist,  a cloud-based list management app. Now when someone eats the last Twinkie, a quick scan of the package looks up the product name via an API call to the UPC database and posts it to Wunderlist. And we’ll bet the red laser beams bouncing around the kitchen make a great nightlight too.

With smartphone barcode reading apps, this might seem a bit like overkill, but we like it just the same. And if barcodes leave you baffled, check out our introduction to these studies in black and white that adorn just about everything.

Fail Of The Week: The Spot Welder Upgrade That Wasn’t

April 22, 2018 by 28 Comments

Even when you build something really, really nice, there’s always room for improvement, right? As it turns out for this attempted upgrade to a DIY spot welder, not so much.

You’ll no doubt recall [Mark Presling]’s remarkably polished and professional spot welder build that we featured some time ago. It’s a beauty, with a lot of thought and effort put into not only the fit and finish but the function as well. Still, [Mark] was not satisfied; he felt that the welder was a little underpowered, and the rewound microwave oven transformer was too noisy. Taking inspiration from an old industrial spot welder, he decided to rebuild the transformer by swapping the double loop of battery cable typically used as a secondary with a single loop of thick copper stock. Lacking the proper sized bar, though, he laminated multiple thin copper sheets together before forming the loop. On paper, the new secondary’s higher cross-sectional area should carry more current, but in practice, he saw no difference in the weld current or his results. It wasn’t all bad news, though — the welder is nearly silent now, and the replaced secondary windings were probably a safety issue anyway, since the cable insulation had started to melt.

Given [Mark]’s obvious attention to detail, we have no doubt he’ll be tackling this again, and that he’ll eventually solve the problem. What suggestions would you make? Where did the upgrade go wrong? Was it the use of a laminated secondary rather than solid bar stock? Or perhaps this is the best this MOT can do? Sound off in the comments section.

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A Polar Coordinate CNC Plotter Even Descartes Could Love

April 20, 2018 by 22 Comments

Take apart a few old DVD drives, stitch them together with cable ties, add a pen and paper, and you’ve got a simple CNC plotter. They’re quick and easy projects that are fun, but they do tend to be a little on the “plug and chug” side. But a CNC plotter that uses polar coordinates? That takes a little more effort.

The vast majority of CNC projects, from simple two-axis plotters to big CNC routers, all tend to use Cartesian coordinate systems, where points on a plane are described by their distances from an origin point on two perpendicular axes. Everything is nice and square, measurements are straightforward, and the math is easy. [davidatfsg] decided to level up his CNC plotter a bit by choosing a polar coordinate system, with points described as a vector extending a certain distance from the origin at a specified angle. Most of the plotter is built from FischerTechnik parts, with a single linear axis intersecting the center point of a rotary drawing platform. Standard G-code is translated to polar coordinates by a Java applet before being sent to a custom Arduino controller to execute the moves. Check out the video below; it’s pretty mesmerizing to watch, and we can’t help but wonder how a polar 3D-printer would work out.

Have polar coordinates got you stumped? It can be a bit of an adjustment from Cartesian space for sure. It can be worth it, though, showing up in everything from cable plotters to POV fidget spinners and even to color space models.

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Marquee Display Uses Six Dozen Surplus VFD Tubes To Great Effect

April 19, 2018 by 6 Comments

The quest to repurpose surplus parts into new and interesting displays never ends, it seems. And the bigger the display, the better, with extra points for using some really obscure part, like these surplus Russian vacuum-fluorescent tubes turned into a marquee display.

As [tonyp7] freely admits, this is a pet project that’s just for the fun of it, made possible by the flood of surplus parts on the market these days. The VFD tubes are IV-25s, Russian tubes that can be had by the fistful for a song from the usual sources. The seven small elements in the tube were intended to make bar graph displays like VU meters, but [tonyp7] ganged up twelve side by side to make 84-pixel displays. The custom driver board for each matrix needs three of the old SN75518 driver chips, in 40-pin DIPs no less. A 3D-printed bracket holds the tubes and the board for each module; it looks like a clock is the goal, with six modules ganged together. But the marquee display shown below is great too, and we look forward to seeing the finished project.

From faux-Nixies made with LEDs to flip-segment displays driven by relay logic to giant seven-segment LEDs that can be 3D-printed, we really like the trend to unique displays. What are you dreaming up?

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