Supercon 2022: Sam Mulvey Shows You How To FM Radio

December 15, 2022 by Elliot Williams 19 Comments

Sam Mulvey built his own radio station in Tacoma, WA. Is there a better way to meld ham radio practice with a colossal number of DIY electrical and computer projects? Sam would say there isn’t one! This 45-minute talk is basically the lessons-learned review of setting up KTQA 95.3 – the radio station on the hill.

Sam starts out the talk by introducing you to LPFM. And maybe you didn’t know that there’s a special type of license issued by the US FCC allowing non-profit community radio stations up to 100 W, covering an radius of around 5 km. It’s like running a pirate radio station, but by jumping through a few legal hoops, made legal.

Trash on the Radio

Putting a radio station together on a budget requires a ton of clever choices, flexibility, and above all, luck. But if you’re willing to repair a busted CD player or turntable, scrounge up some used computers, and work on your own amplifiers, the budget doesn’t have to be the limiting factor.

Being cheap means a lot of DIY. For instance, Sam and friends made a custom console to support all the gear and hide all the wiring. Some hot tips from the physical build-out: painted cinderblocks make great studio monitor stands, and Cat-5 can carry two channels of balanced audio along with power, with sufficient isolation that it all sounds clean. Continue reading “Supercon 2022: Sam Mulvey Shows You How To FM Radio” →

Omniwhegs Are Awesome Times Two

December 14, 2022 by Elliot Williams 26 Comments

What’s the strangest wheel? The omniwheel. Unless you count whegs — “wheel legs” — as wheels. This research paper from Shanghai Technical University explores a mash-up of the two ideas, where the wheels roll as standard omniwheels until a servo on the axle unfurls them into their whegs configuration. The result? OmniWhegs!

The resulting vehicle is a bit of a departure from the original whegs concept, which used compliant mechanisms which passively balanced the force across the legs. Here, the omniwhegs are rigid and actually use a synchronization routine that you can see in the video embedded below.

If you can’t get enough omniwheels, you’re not alone. Here’s a rare three-wheeler, and here’s an omniwheel made of MDF. We haven’t seen enough whegs-based bots, but OutRunner is pretty astounding, and we think deserves a second look.

We’ve also seen wheels that convert to whegs before, but without the omni. And we don’t know if that one ever made it out of render-of-a-robot phase.

So kudos to the Shanghai team for taking the strangest possible wheels and actually building them!

Continue reading “Omniwhegs Are Awesome Times Two” →

After 40 Years, Adobe Releases PostScript Source V0.10 For Posterity

December 13, 2022 by Elliot Williams 28 Comments

Celebrating their 40th anniversary, Adobe released the source code of PostScript v0.10 to the Computer History Museum. But before you ask, we tried and it won’t compile with GCC out of the box – it’s missing at least except.h, but we’d bet you can hack around it with a little dedication.

PostScript is the precursor to PDF, and at the time it was revolutionary. Coming out of Xerox’s PARC, the idea was to create device- and resolution-independent documents where all the characters, symbols, and graphics are described by their shapes instead of bitmaps. PostScript’s secret sauce was in how it went back to a pixel-based representation for end use on monitors or printers. It’s no exaggeration to say that this ended up revolutionizing the print industry, and it makes sense in the CHM’s collection.

Still, on the trade-secret front, you shouldn’t get too excited. Apparently the code released here only includes a first-draft version of Adobe’s font hinting algos, as evidenced by the early version number. Nonetheless, you’re free to dig into pretty readable C. For instance, vm.c contains the virtual machine that implements PostScript’s almost Forth-like language.

Of course, if you’d just like to mess around with PostScript, downloading a modern open-source interpreter like GhostScript probably makes a lot more sense. Even so, it’s fun to see the original codebase where it all started.

Fossil Files: My .Emacs

December 10, 2022 by Elliot Williams 63 Comments

Last week, I wrote about cargo culting in a much more general context, so this week I’m going to come clean. The file that had me thinking about the topic was the worst case you’ve probably ever seen: I have a .emacs file kicking around that I haven’t really understood since I copied it from someone else – probably Ben Scarlet whose name is enshrined therein – in the computer lab in 1994! Yes, my .emacs file is nearly 30, and I still don’t really understand it, not exactly.

Now in my defence, I switched up to vim as my main editor a few years ago, but this one file has seen duty on Pentiums running pre-1.0 versions of Linux, on IBM RS/6000 machines in the aforementioned computer lab, and on a series of laptops and desktops that I’ve owned over the years. It got me through undergrad, grad school, and a decade of work. It has served me well. And if I fired up emacs right now, it would still be here.

For those of you out there who don’t use emacs, the .emacs file is a configuration file. It says how to interpret different files based on their extensions, defines some special key combos, and perhaps most importantly, defines how code syntax highlighting works. It’s basically all of the idiosyncratic look-and-feel stuff in emacs, and it’s what makes my emacs mine. But I don’t understand it.

Why? Because it’s written in LISP, for GNU’s sake, and because it references all manner of cryptic internal variables that emacs uses under the hood. I’m absolutely not saying that I haven’t tweaked some of the colors around, or monkey-patched something in here or there, but the extent is always limited to whatever I can get away with, without having to really learn LISP.

This ancient fossil of a file is testament to two things. The emacs codebase has been stable enough that it still works after all this time, but also that emacs is so damn complicated and written in an obscure enough language that I have never put the time in to really grok it – the barriers are too high and the payoff for the effort too low. I have no doubt that I could figure it out for real, but I just haven’t.

So I just schlep this file around, from computer to computer, without understanding it and without particularly wanting to. Except now that I write this. Damnit.

Featured image: “A Dusty Old Book” by Marco Verch Professional.

Cargo Culting And Buried Treasure

December 3, 2022 by Elliot Williams 55 Comments

I have no idea how true the stories are, but legend has it that when supplies were dropped on some Melanesian islands during WWII, some locals took to replicating runway signs in order to further please the “gods” that were dropping them. They reportedly thought that making landing strips caused laden airplanes to visit. Richard Feynman later turned this into a metaphor about scientific theory – that if you don’t understand what you’re doing deeply, you may be fooling yourself.

I’d like to be a little bit more forgiving of adherents of technological cargo cults. Because the world around us is very complicated, we often just take things as they are rather than understanding them deeply, because there’s simply only so deep you can go into so many fields.

Is someone who doesn’t know the i386 machine language cargo-culting their way through a job as a web backend developer? Probably not. But from the perspective of an assembly-language programmer, any of us who write in compiled or interpreted programming languages are cargo-culting coding. You don’t need to understand a cell phone to dial home, but can you really say that you understand everything about how one works? Or are you just going through the motions?

So while some reliance on metaphor and “well, it worked last time” is perfectly normal, I think noticing when you cargo-cult is also healthy. It should also be a warning sign, or at least a flag to remind yourself that there may be dragons here. Or maybe just a buried learning opportunity, the X that marks the spot where digging deeper might be productive.

A Hacker Walks Into A Trade Show: Electronica 2022

November 22, 2022 by Elliot Williams 24 Comments

Last week, the world’s largest electronics trade fair took place in Munich, so I had to attend. Electronica is so big that it happens only once every two years and fills up 14 airplane hangars. As the fairly generic name suggests, it covers anything and everything having to do with electronics. From the producers of your favorite MLCC capacitors to the firms that deliver them to your doorstep, from suppliers of ASIC test equipment to the little shop that’ll custom wind toroids for you, that’s a pretty wide scope. Walking around, I saw tomorrow’s technology today from the big players, but I also picked up some ideas that would be useful for the home gamer.

When I first walked in, for instance, I ran into the Elantas booth. They’re a company that makes flexible insulation and specialty industrial coatings. But what caught my eye was a thermoformed plastic sheet with circuit traces on it. To manufacture them, they cut out copper foil, glue it to a flat plastic sheet with a glue that has a little give, and then put it all together into a vacuum former. The result is a 3D circuit and organically formed substrate in one shot. Very cool, and none of the tech for doing that is outside of the reach of the determined hacker.

The Cool Stuff

All of the stands, big or small, try to lure you in with some gimmick. The big fish, firms with deep pockets, put up huge signs and open bars, and are staffed by no shortage of salespeople in suits. The little fish, on the other hand, have to resort to showing you the cool stuff that they do, and it’s more often the application engineers sitting there, ready to talk tech. You can guess which I found more interesting.

For instance when I walked up to an obviously DIY popcorn popper that was also showing 5000 FPS footage of kernels in mid-pop, I had to ask. The company in question was a small UK outfit that made custom programmable power supplies and digital acquisition gear that interfaced with it. You could plug in their box to some temperature probes, fire off the high-speed video camera, and control the heating and cooling profile without writing any code. Very sweet. Continue reading “A Hacker Walks Into A Trade Show: Electronica 2022” →