Finding The Right Hack Is Half The Battle

September 18, 2021 by Elliot Williams 25 Comments

Sometimes you just get lucky. I had a project on my list for a long time, and it was one that I had been putting off for a few months now because I loathed one part of what it entailed — sensitive, high-accuracy analog measurement. And then, out of the blue I stumbled on exactly the right trick, and my problems vanished in thin air. Thanks, Internet of Hackers!

The project in question is a low-vacuum regulator for “bagging” fiberglass layups. What I needed was some way to read a pressure sensor and turn on and off a vacuum pump accordingly. The industry-standard vacuum gauges are neat devices, essentially a tiny little strain gauge on a membrane between the vacuum side and the atmosphere side, in a package the size of a dime. (That it’s a strain gauge is foreshadowing, but I didn’t know that at the time.) I bought one for $15 ages ago, and it sat on my desk, awaiting its analog circuitry.

See, the MPX2100 runs on 12 V and puts out a signal around 40 mV on top of a 6 V offset. That voltage level is inconvenient for modern 3.3 V microcontroller ADCs, and the resolution would get clobbered by the 6 V signal if I just put a voltage divider on it. This meant whipping together some kind of instrument amplifier circuit to null out the 6 V and amplify the 40 mV for the ADC. The circuits I found online all called for 1% resistors in values I didn’t have, and mildly special op-amps. No fun, for me at least. So there it sat.

Picture of sketchy-looking vacuum apparatus. — Cut the blue wire or the red wire? HX711 module and pressure sensor on the left.

Until I ran into this project that machetes through the analog jungle with one part, and it happened to be one I had on hand. A vacuum pressure sensor is a strain gauge, set up like a Wheatstone bridge, just like you would use for weighing something with a load cell. The solution? A load-cell ADC chip, the HX711, found in every cheap scale or online for under a buck. The only other trick was finding a low-voltage pressure sensor to work with it, but that turns out to be easy as well, and I had one delivered in two days.

In all, this project took months of foot-dragging, but only a few clicks and five minutes of soldering once I got the right idea. The industrial applications and manufacturers’ app notes all make sense if you are making hundreds or millions of these devices, where the one-time cost of prototyping up the hard bits gets amortized, but the hacker solution of using a weight-scale chip was just the ticket for a one-off. That just goes to show how useful sharing our tips and tricks can be — you won’t get this from the industry. So send us your success stories, and your useful failures too, and Read More Hackaday!

A Rant On Personal Software Projects

September 14, 2021 by Matthew Carlson 41 Comments

Looking across your hard drive and GitHub, you might find hundreds of notes and skeletons of Git repositories. A veritable graveyard of software side projects. The typical flow for many of these projects is: get an idea, ruminate on the idea until it becomes exciting, eventually becoming more exciting than the current side project, notes are captured, a repository is created, and work begins at a blistering pace as the focus and excitement are there. There might be some rewrites or some changes in direction. Questions of whether the project is worthwhile or “what even should this project actually be” start to arise. Eventually, enthusiasm wanes as these questions continue to multiply. Progress slows as the path forward seems less clear-cut as it once did. The project is either sunset with a mournful promise to someday return or quietly put aside as something new and exciting comes to take its place. Sound familiar? Perhaps not, but the principles here could be helpful.

This particular article is largely a piece of opinion from one engineer to another. It’s about engineering the process by which you design a project to have better outcomes. There are many reasons why a project could be shelved or scrapped and not all of them are from a lack of clear project definition. In the case where it isn’t clear what the project is, it can be helpful to think about it in a more holistic/meta sense. There are two types of personal projects in broad strokes: technology demos and products.

Continue reading “A Rant On Personal Software Projects” →

Who Owns The Machine Anyway?

August 28, 2021 by Elliot Williams 42 Comments

The story of the McDonalds’ frozen treat machine involves technology, trade secrets, inside business dealings, franchiser/franchisee friction, and an alleged NDA violation. In short: lots of money and lawyers. But it also involves something that matters to all of us hackers — what it means to own a machine.

The brief background is that McDonald’s requires its franchisees to buy a particular Taylor Soft Serve machine. The machine would enter pasteurizing mode and has opaque error codes that are triggered apparently without the owners or operators understanding, at which point Taylor service techs come in to fix them — and get paid for their service, naturally. A small hardware startup, Kytch, stepped into the mess with a device that man-in-the-middles the Taylor machine’s status codes, allowing the machine’s owners to diagnose and monitor it themselves. Heroes, right?

Taylor, naturally, wants to look at a Kytch device, but they’re locked up under NDAs that Kytch require users to sign in order to protect their trade secrets. So when Taylor gets their hands on one, Kytch takes them to court for, ironically, reverse engineering their device that they built to reverse Taylor’s protocols.

There are no good guys in this fight: it’s corporate secrecy fighting corporate secrets. None of which, by the way, is Hackaday particularly fond of. Why? Because these secrets rob the ostensible owners of the devices of their ability to inspect, fix, and operate their machines. This is akin to the “right to repair” idea, but it’s somehow even more fundamental — the right to know what your own devices are doing.

What this story needs is a Robin Hood. And as the devices we get sold become increasingly wrapped up in EULAs and NDAs, and full of secret sauce that’s out of our control, we’re going to need a lot more Robin Hoods. It’s McDonald’s frozen treat machines, but it’s also your smart thermostat and your inkjet printer and your — you name it. Have at it, Hackaday!

Robot Utopia

We see so many dystopian visions of automation, it’s time for us to do it right! The Redefine Robots round of the 2021 Hackaday Prize just started, and it’s your chance to build robots that respect the users. It doesn’t have to be the largest project in the world, but it does have to be automatic and helpful. Start your engines!

Ask Hackaday: What Is Amazon Thinking By Entering The Palm-Reading Business?

August 27, 2021 by Kristina Panos 60 Comments

Have you heard about this One? At least three United States senators have, and they want to know what Amazon plans to do with all the biometric data collected by the Amazon One program. It’s their new contactless payment method that uses your unique palm print instead of cards or phones to make purchases, gain access to venues of work and play, and enter or pay in whatever other spaces Amazon can invade down the line. The idea is that one day, we’ll all be able to leave our homes without any form of money or ID of any kind, because we’ll all be stored away in Bezos’ big biometric file cabinet.

We tossed this one around in the writer’s room back when the Amazon One concept was nothing but a pile of buzzwords and a render or two, but these kiosks are now active in 50+ Whole Foods and Amazon 4-Star locations across the US. Here’s the deal: you can only sign up at a participating store that has a kiosk, because they have to scan your palms into the system. We were worried that the signup kiosk could easily take fingerprint scans at the same time, but according to the gifs in Morning Brew’s review, it just uses another of their point-of-sale palm scanners along with a touch screen and a card reader. But you still have to hover your entire hand over it, so who’s to say that the scan ends where the fingers begin?

Continue reading “Ask Hackaday: What Is Amazon Thinking By Entering The Palm-Reading Business?” →

Freezing Out Ice Cream Machine Competition

August 23, 2021 by Al Williams 47 Comments

We always knew that McDonald’s soft serve (you can’t really call it ice cream) machines are known to be finicky. There’s even a website that tracks where the machines are broken and, apparently, it is usually about 10% or more of them at any given time. But when we saw a news article about a judge issuing a restraining order, we knew there must be more to the story. Turns out, these $18,000 soft serve machines are in the heart of something we are very interested in: when do you own your own technology?

Cold Tech

There are apparently 13,000 or so of these machines and they are supposedly high-tech marvels, able to produce soft serve and milkshakes at the same time. However, they are also high maintenance. Cleaning the machine every two weeks (try not to think about that) involves a complete teardown. Worse, if anything breaks, you need a factory-authorized service person.

Continue reading “Freezing Out Ice Cream Machine Competition” →

Goals And Goalposts

August 14, 2021 by Elliot Williams 14 Comments

In the winter, I hatched a vague plan to learn some of the modern unmanned aerial vehicle tech. Everybody needs an autonomous vehicle, and we’ve got some good flying fields within walking distance, so it seemed like it could work. Being me, that meant buying the cheapest gear that could possibly work, building up the plane by myself, and generally figuring out as much as possible along the way. I learn more by making my own mistakes anyway. Sounds like a good summer project.

Fast-forward to August, and the plane is built, controller installed, and I’ve spent most of the last month trying to make them work well together. (The firmware expects a plane with ailerons, and mine doesn’t have them, but apparently I’d rather tweak PID values than simply add a couple wing servos.) But it’s working well enough that it’s launching, flying autonomous waypoint missions, and coming home without any intervention. So, mission accomplished, right?

Nope. When I’m enjoying a project, I have a way of moving the goalposts on myself. I mean, I don’t really want to be done anyway. When a friend asked me a couple weeks ago what I was planning to do with the plane, I said “take nice aerial videos of that farm over there.” Now I see flight opportunities everywhere, and need to work on my skills. The plane needed an OLED display. It probably still needs Bluetooth for local configuration as well. Maybe a better long-range data link…

This is creeping featurism and moving-the-goalposts in the best of ways. And if this were a project with a deadline, or one that I weren’t simply enjoying, it would be a problem. Instead, having relatively low-key goals, meeting them, and letting them inspire me to set the next ones has been a blast. It makes me think of Donald Papp’s great article on creating hacking “win” projects. There he suggests creating simple goals to keep yourself inspired. I don’t think I could have planned out an “optimal” set of goals to begin with — I’ve learned too much along the way that the next goal isn’t obvious until I know what new capabilities I have. Creeping is the only way.

What about you? Do you plan your hobby projects completely in advance? Not at all? Or do you have some kind of hybrid, moving-the-goalposts sort of strategy?

Hearing The Unhearable

August 7, 2021 by Elliot Williams 51 Comments

My wife was watching a crime drama, and one of the plot twists involved a witness’ hearing aid malfunctioning so that he could hear electromagnetic waves around him. It’s not so implausible, if you think about it. Many hearing aids have a t-coil, which is essentially an inductor that’s designed to couple with the speaker in a telephone. If that went haywire, maybe you could hear all the changing magnetic fields around you, and if you could escape the constant hum of the mains power line, it might even be interesting.

So of course, she turns to me and says “we need to make one!” It shouldn’t be hard at all — a big inductor and an amplifier should do the trick. In fact, it’ll probably be easy enough that it’ll make a good introduction-to-electronics project for my son. But there are also enough unknowns here that it’ll be interesting. How big a coil? How close? How sensitive? What about that mains frequency bit? Ferrite core or not?

None of this is rocket science, for sure, but it will probably be full of kludges, discoveries, and straight-up exploration. In short, the perfect weekend project. And in the end, it’ll expose something that’s normally invisible, and that’s where the fun lies.

This must be the same urge that drove Faraday and Marconi, Volta and Maxwell. There’s something amazing about directly sensing, seeing, hearing, and understanding some of the stuff that’s outside of our limited hearing and eyesight, and yet is all around us. I can write down the equations that describe it — I learned them in school after all — but there’s no substitute for poking around in your own home. Who knows, maybe in a few more weekends we’ll build ourselves an all-band receiver.

What’s your favorite super power?