Last week, [Al Williams] wrote up a his experience with a book that provided almost too much detailed information on how to build a DIY x-ray machine for his (then) young soul to bear. He almost had to build it! Where the “almost” is probably both a bummer because he didn’t have an x-ray machine as a kid, but also a great good because it was a super dangerous build, of a typical sort for the 1950s in which it was published.

Part of me really loves the matter-of-factness with which “A Boy’s First Book of Linear Accelerators” tells you how you (yes you!) can build a 500 kV van der Graff generator. But at the same time, modern me does find the lack of safety precautions in many of these mid-century books to be a little bit spooky. Contrast this with modern books where sometimes I get the feeling that the publisher’s legal team won’t let us read about folding paper airplanes for fear of getting cut.

A number of us have built dangerous projects in our lives, and many of us have gotten away with it. Part of the reason that many of us are still here is that we understood the dangers, but I would be lying if I said that I always fully understood them. But thinking about the dangers is still our first and best line of defense. Humility about how well you understand all of the dangers of a certain project is also very healthy – if you go into it keeping an eye out for the unknown unknowns, you’re in better shape.

Safety isn’t avoiding danger, but rather minimizing it. When we publish dangerous hacks, we really try to at least highlight the most important hazards so that you know what to look out for. And over the years, I’ve learned a ton of interesting safety tricks from the comments and fellow hackers alike. My ideal, then, is the spirit of the 1950s x-ray book, which encourages you to get the hack built, but modernized so that it tells you where the dangers lie and how to handle them. If you’re shooting electrons, shouldn’t the book also tell you how to stay out of the way?

It is funny how sometimes things you think are bad turn out to be good in retrospect. Like many of us, when I was a kid, I was fascinated by science of all kinds. As I got older, I focused a bit more, but that would come later. Living in a small town, there weren’t many recent science and technology books, so you tended to read through the same ones over and over. One day, my library got a copy of the relatively recent book “The Amateur Scientist,” which was a collection of [C. L. Stong’s] Scientific American columns of the same name. [Stong] was an electrical engineer with wide interests, and those columns were amazing. The book only had a snapshot of projects, but they were awesome. The magazine, of course, had even more projects, most of which were outside my budget and even more of them outside my skill set at the time.

If you clicked on the links, you probably went down a very deep rabbit hole, so… welcome back. The book was published in 1960, but the projects were mostly from the 1950s. The 57 projects ranged from building a telescope — the original topic of the column before [Stong] took it over — to using a bathtub to study aerodynamics of model airplanes.

X-Rays

However, there were two projects that fascinated me and — lucky for me — I never got even close to completing. One was for building an X-ray machine. An amateur named [Harry Simmons] had described his setup complaining that in 23 years he’d never met anyone else who had X-rays as a hobby. Oddly, in those days, it wasn’t a problem that the magazine published his home address.

You needed a few items. An Oudin coil, sort of like a Tesla coil in an autotransformer configuration, generated the necessary high voltage. In fact, it was the Ouidn coil that started the whole thing. [Harry] was using it to power a UV light to test minerals for flourescence. Out of idle curiosity, he replaced the UV bulb with an 01 radio tube. These old tubes had a magnesium coating — a getter — that absorbs stray gas left inside the tube.

The tube glowed in [Harry’s] hand and it reminded him of how an old gas-filled X-ray tube looked. He grabbed some film and was able to image screws embedded in a block of wood.

However, 01 tubes were hard to get even then. So [Harry], being what we would now call a hacker, took the obvious step of having a local glass blower create custom tubes to his specifications.

Given that I lived where the library barely had any books published after 1959, it is no surprise that I had no access to 01 tubes or glass blowers. It wasn’t clear, either, if he was evacuating the tubs or if the glass blower was doing it for him, but the tube was down to 0.0001 millimeters of mercury.

Why did this interest me as a kid? I don’t know. For that matter, why does it interest me now? I’d build one today if I had the time. We have seen more than one homemade X-ray tube projects, so it is doable. But today I am probably able to safely operate high voltages, high vaccums, and shield myself from the X-rays. Probably. Then again, maybe I still shouldn’t build this. But at age 10, I definitely would have done something bad to myself or my parent’s house, if not both.

Then It Gets Worse

The other project I just couldn’t stop reading about was a “homemade atom smasher” developed by [F. B. Lee]. I don’t know about “atom smasher,” but it was a linear particle accelerators, so I guess that’s an accurate description.

I doubt I have the chops to pull this off today, much less back then. Old refigerator compressors were run backwards to pull a rough vaccuum. A homemade mercury diffusion pump got you the rest of the way there. I would work with some of this stuff later in life with scanning electron microscopes and similar instruments, but I was buying them, not cobbling them together from light bulbs, refigerators, and home-made blown glass!

You needed a good way to measure low pressure, too, so you needed to build a McLeod gauge full of mercury. The accelerator itself is three foot long,  borosilicate glass tube, two inches in diameter. At the top is a metal globe with a peephole in it to allow you to see a neon bulb to judge the current in the electron beam. At the bottom is a filament.

The globe at the top matches one on top of a Van de Graf generator that creates about 500,000 volts at a relatively low current. The particle accelerator is decidedly linear but, of course, all the cool particle accelerators these days form a loop.

[Andres Seltzman] built something similar, although not quite the same, some years back and you can watch it work in the video below:

What could go wrong? High vacuum, mercury, high voltage, an electron beam and plenty of unintentional X-rays. [Lee] mentions the danger of “water hammers” in the mercury tubes. In addition, [Stong] apparently felt nervous enough to get a second opinion from [James Bly] who worked for a company called High Voltage Engineering. He said, in part:

…we are somewhat concerned over the hazards involved. We agree wholeheartedly with his comments concerning the hazards of glass breakage and the use of mercury. We feel strongly, however, that there is inadequate discussion of the potential hazards due to X-rays and electrons. Even though the experimenter restricts himself to targets of low atomic number, there will inevitably be some generation of high-energy X-rays when using electrons of 200 to .300 kilovolt energy. If currents as high as 20 microamperes are achieved, we are sure that the resultant hazard is far from negligible. In addition, there will be substantial quantities of scattered electrons, some of which will inevitably pass through the observation peephole.

I Survived

Clearly, I didn’t build either of these, because I’m still here today. I did manage to make an arc furnace from a long-forgotten book. Curtain rods held carbon rods from some D-cells. The rods were in a flower pot packed with sand. An old power cord hooked to the curtain rods, although one conductor went through a jar of salt water, making a resistor so you didn’t blow the fuses.

Somehow, I survived without dying from fumes, blinding myself, or burning myself, but my parent’s house had a burn mark on the floor for many years after that experiement.

If you want to build an arc furnace, we’d start with a more modern concept. If you want a safer old book to read, try the one by [Edmund Berkeley], the developer of the Geniac.

Every once in a while, there’s a Hackaday article where the comments are hands-down the best part of a post. This happened this week with Al Williams’ Ask Hackaday: How Do You Make Front Panels?. I guess it’s not so surprising that the comments were full of awesome answers – it was an “Ask Hackaday” after all. But you all delivered!

A technique that I had never considered came up a few times: instead of engraving the front of an opaque panel, like one made of aluminum or something, instead if you’re able to make the panel out of acrylic, you can paint the back side, laser or engrave into it, and then paint over with a contrast color. Very clever!

Simply printing the panel out onto paper and laminating it got a number of votes, and for those who are 3D printing the enclosure anyway, simply embossing the letters into the surface had a number of fans. The trick here is in getting some contrast into the letters, and most suggested changing filament. All I know is that I’ve tried to do it by painting the insides of the letters white, and it’s too fiddly for me.

But my absolute favorite enclosure design technique got mentioned a number of times: cardboard-aided design. Certainly for simple or disposable projects, there’s nothing faster than just cutting up some cardboard and taping it into the box of your desires. I’ll often do this to get the sizes and locations of components right – it’s only really a temporary solution. Although some folks have had success with treating the cardboard with a glue wash, paint, or simply wrapping it in packing tape to make it significantly more robust. Myself, if it ends up being a long-term project, I’ll usually transfer the cardboard design to 3DP or cut out thin plywood.

I got sidetracked here, though. What I really wanted to say was “thanks!” to everyone who submitted their awesome comments to Al’s article. We’ve had some truly hateful folks filling the comment section with trash lately, and I’d almost given up hope. But then along comes an article like this and restores my faith. Thanks, Hackaday!

Watching a video about a scratch-built ultra-precise switch for metrology last week reminded me that it’s not always the projects that are the most elegant solutions that I enjoy reading about the most. Sometimes I like reading about hackers’ projects more for the description of the problem they’re facing.

A good problem invites you to brainstorm along. In the case of [Marco Reps]’s switches, for instance, they need to be extraordinarily temperature stable, which means being made out of a single type of metal to avoid unintentional thermocouple joints. And ideally, they should be as cheap as possible. Once you see one good solution, you can’t help but think of others – just reading the comments on that article shows you how inspiring a good problem can be. I’m not worried about these issues in any of my work, but it would be cool to have to.

Similarly, this week, I really liked [Michael Prasthofer]’s deep dive into converting a normal camera into a spectrometer. His solutions were all very elegant, but what was most interesting were the various problems he faced along the way. Things that you just wouldn’t expect end up mattering, like diffraction gratings being differently sensitive across the spectrum when light comes in from different angles. You can learn a lot from other people’s problems.

So, hackers everywhere, please share your problems with us! You think that your application is “too niche” to be of general interest? Maybe it’s another example of a problem that’s unique enough to be interesting just on its own. Let’s see what your up against. A cool problem is at least as interesting as a clever solution.

In the early days of the internet, online conversations were an event. The technology was novel, and it was suddenly possible to socialize with a whole bunch of friends at a distance, all at once. No more calling your friends one by one, you could talk to them all at the same time!

Many of us would spend hours on IRC, or pull all-nighters bantering on MSN Messenger or AIM. But then, something happened, and many of us found ourselves having shorter conversations online, if we were having any at all. Thinking back to my younger days, and comparing them with today, I think I’ve figured out what it is that’s changed.

Deliberate Choices

Twenty five years ago, a lot more of us were stuck getting by with dialup. The Internet wasn’t always on back then. You had to make the decision to connect to it, and sit at your computer to use it.

Similarly, logging into an IRC room was a deliberate action. It was a sign that you were setting aside time to communicate. If you were in a chat room, you were by and large there to talk. On AIM or MSN Messenger, it was much the same deal. If you wanted to have a chat, you’d leave your status on available. If you didn’t wanna talk, you’d set yourself to Busy or Away, or log off entirely.

This intentionality fostered meaningful interactions online. Back then, you’d sign in and you’d flick through your list of friends. If someone’s icon was glowing green, you knew they were probably up to talk. You might have a quick chat, or you could talk for hours. Indeed, logging on to a chatroom for an extended session was a pastime enjoyed by many.

Back then, people were making the conscious decision to set aside time to talk. Conversations were more focused and meaningful because both parties had set aside time to engage. This intentionality led to richer, more engaging discussions because participants were fully present.

Furthermore, the need to log in and out helped create a healthy boundary between life online and off. Users balanced their online interactions with other responsibilities and activities. There was a clear distinction between online and offline life, allowing for more complete engagement in both. When you logged off, that was it. There was no way for your online friends to get a message to you in real time, so your focus was fully on what was going on in front of you.

Critical Shift

T’was the endless march of technology that changed the meta. Broadband internet would keep our computers online round the clock. You could still log in and out of your chat apps, of course, and when you walked away from your computer, you were offline.

But technology didn’t stop there. Facebook came along, and tacked on Messenger in turn. The app would live on the smartphones in our pockets, while mobile data connections meant a message from the Internet could come through at any time.

Facebook’s always-on messaging was right there, tied to a website many of us were already using on the regular. Suddenly, booting up another app like AIM or MSN seemed archaic when we could just chat in the browser. The addition of the app to smartphones put Messenger everywhere we went. For many, it even started to supplant SMS, in addition to making other online chat platforms obsolete.

Always-on messaging seemed convenient, but it came with a curse. It’s fundamentally changed the dynamics of our online interactions, and not always for the better.

Perpetual availability means that there is a constant pressure to respond. In the beginning, Facebook implemented “busy” and “available” status messages, but they’re not really a thing anymore. Now, when you go to message a friend, you’re kind of left in to the dark as to what they’re doing and how they’re feeling. Maybe they’re chilling at home, and they’re down for a deep-and-meaningful conversation. Or maybe they’re working late at work, and they don’t really want to be bothered right now. Back in the day, you could seamlessly infer their willingness to chat simply by noting whether they were logged in or not. Today, you can’t really know without asking.

That has created a kind of silent pressure against having longer conversations on Facebook Messenger. I’m often reluctant to start a big conversation with someone on the platform, because I don’t know if they’re ready for it right now. Even when someone contacts me, I find myself trying to close out conversations quickly, even positive ones. I’m inherently assuming that they probably just intended to send me a quick message, and that they’ve got other things to do. The platform provides no explicit social signal that they’re happy to have a proper conversation. Instead, it’s almost implied that they might be messaging me while doing something else more important, because hey, Messenger’s on all the time. Nobody sits down to chat on Facebook Messenger these days.

It’s also ruining the peace. If you’ve got Messenger installed, notifications pop up incessantly, disrupting focus and productivity. Conversations that might have once been deep and meaningful are now often fragmented and shallow because half the time, someone’s starting them when you’re in the middle of something else. If you weren’t “logged on” or “available”, they’d wait until you were ready for a proper chat. But they can’t know that on Facebook Messenger, so they just have to send a message and hope.

In a more romantic sense, Facebook Messenger has also killed some of the magic. The ease of starting a conversation at any moment diminishes the anticipation that once accompanied online interactions. Plenty of older Internet users (myself included) will remember the excitement when a new friend or crush popped up online. You could freely leap into a conversation because just by logging on, they were saying “hey, wanna talk?” It was the equivalent social signal of seeing them walk into your local pub and waving hello. They’re here, and they want to socialize!

It’s true that we effectively had always-on messaging before Facebook brought it to a wider audience. You could text message your friends, and they’d get it right away. But this was fine, and in fact, it acted as a complement to online messaging. SMSs used to at least cost a little money, and it was generally time consuming to type them out on a limited phone keypad. They were fine if you needed to send a short message, and that was about it. Meanwhile, online messaging was better for longer, intentional conversations. You could still buzz people at an instant when you needed to, but SMS didn’t get in the way of proper online chats like Facebook Messenger would.

The problem is, it seems like we can’t really go back. As with so many technologies, we can try and blame the creators, but it’s not entirely fair. Messenger changed how we used online chat, but Facebook didn’t force us to do anything. Many of us naturally flocked to the platform, abandoning others like AIM and MSN in short order .We found  it more convenient in the short term, even if some of us have found it less satisfying in the long term.

Online platforms tend to figure out what we respond to on a base psychological level, and game that for every last drop of interaction and attention they can. They do this to sell ads and make money, and that’s all that really matters at the end of the day. Facebook’s one of the best at it. It’s not just online chat, either. Forums went the same way, and it won’t end there.

Ultimately, for a lot of us, our days of spending hours having great conversations online are behind us. It’s hard to see what could ever get the broader population to engage again in that way. Instead, it seems that our society has moved on, for the worse or for the better. For me, that’s a shame!

I really enjoyed reading Anne Ogborn’s piece on making simple DIY measurement devices for physical quantities like force, power, and torque. It is full of food for thought, if you’re building something small with motors and need to figure out how to spec them out.

Aside from a few good examples, what I really took home from this piece is how easy it can be to take approximate measurements. Take the push stick, which is a spring-loaded plunger in a transparent barrel. You use it to measure force by, well, squeezing the spring and reading off how far it deflects. That’s obvious, but the real trick is in calibration by pushing it into a weighing scale and marking divisions on the barrel. That quickly and easily turns “it’s pressing this hard” into an actual numerical force measurement.

The accuracy and precision of the push stick are limited by the quality of your scale and the fineness of the pen tip that you use to mark the barrel. But when you’re just looking to choose among two servo motors, this kind of seat-of-the-pants measure is more than enough to buy the right part. Almost any actual measurement is better than a wild-ass guess, so don’t hold yourself to outrageous standards or think that improvised quantitative measurement devices aren’t going to get the job done.

Al Williams quoted a teacher of his as saying that the soul of metrology is “taking something you know and using it to find something you don’t know”, and that sums up this piece nicely. But it’s also almost a hacker manifesto: “take something you can do and use it to do something that you can’t (yet)”.

Got any good measurement hacks you’d like to share?

It’s often said of us humans that we’re the only “tool-using mammals”. While not exclusive to the hacker community, a bunch of us are also “tool-building mammals” when we have the need or get the free time. I initially wanted to try to draw some distinction between the two modes, but honestly I think all good hackers do both, all the time.

We were talking about the cool variety of test probes on the podcast, inspired by Al Williams’ piece on back probes. Sometimes you need something that’s needle-thin and can sneak into a crimp socket, and other times you need something that can hold on like alligator clips. The infinite variety of jigs and holders that make it easier to probe tiny pins is nothing short of amazing. Some of these are made, and others bought. You do what you can, and you do what you need to.

You can learn a lot from looking at the professional gear, but you can learn just as much from looking at other hackers’ bodge jobs. In the podcast, I mentioned one of my favorite super-low-tech hacks: making a probe holder out of a pair of pliers and a rubber band to hold them closed. Lean this contraption onto the test point in question and gravity does the rest. I can’t even remember where I learned this trick from, but I honestly use it more than the nice indicator-arm contraptions that I built for the same purpose. It’s the immediacy and lack of fuss, I think.

So what’s your favorite way of putting the probe on the point? Home-made and improvised, or purpose-built and professional? Or both? Let us know!