Junkbox Confidential

Thomas Edison famously quipped “To invent, you need a good imagination and a pile of junk.” Amen, brother. My personal junk pile (ahem, collection of pre-owned electromechanical curiosities) is certainly a source of spare parts, but also a source of surprise and wonder. Sometimes the junk itself spurs the imagination, but sometimes junk is just junk.

There are pieces of used gear that I bought for some particular plan, maybe a decade ago?, and totally forgot. While it’s fun to rediscover them — I bought six used super-soaker pump assemblies, and summer is just around the corner — the sad truth is often that the forgotten pieces were forgotten for a reason. Whatever kooky idea I had at the time has faded, and the parts are all that’s left.

But among these miserable creatures, there are some absolute gems. Parts that continually call out to be used. Bits that would fire even Thomas Edison’s imagination. Unforgetable junk.
Mostly, it’s their physicality that calls out to me. I have a stack of old 5″ hard drive platters, gutted, and converted into essentially a rotary encoder. For years, I used it as a USB scroll wheel on my desk, but most recently it has made reappearances in other goofy projects — a music box for my son that played notes in a row depending on how fast you spun it, and most recently a jog wheel for a one-meter linear motion project that hasn’t really found its full expression yet, but might become a camera slider. Anyway, when I needed a nice physical rotary encoder knob, the hard drive was just sitting there waiting to be used.

An old rotary dial phone also falls in this category. It ends in a barrel jack instead of an RJ45, so it’s easy to incorporate into other projects. Previously, it’s been the interface for a USB dial-a-password device, but it got supplanted by software that takes up less desk space. I’m sure I’ll come up with something else for it to do.

The undisputed kings of my unforgettable junk, that I haul out year after year, are two Magellan Space Mice. They are the old serial port kind, speaking 9600 baud to any microcontroller, and are easy to interface with. They put out six axes of control plus a few buttons, and they’re frankly a technological marvel. These have been used for remote control cars, and even once for a ride-on vehicle, but only briefly because it was too dangerous. I’ve never managed to use more than four axes at once, but that implicit challenge is part of their charm.

In the strangest turn of events, the maintainer of the Linux Spacenav driver project, John Tsiombikas, pulled the serial Space Mice into the code base in December. So now I’m using both of them for their intended purpose — manipulation of 3D designs in CAD/CAM software — one in the office and one in the workshop. Not a hack!

It was great to have the Space Mice in the junk box; they were truly inspirational. On one hand, being promoted into everyday use is the ultimate goal, I guess, but it still leaves a hole in my heart. I’ll be keeping my eyes out for a couple more, I think. The junk box hungers.

A Lot Of Effort For A Pi Laptop

Building a Raspberry Pi laptop is not that uncommon. In fact, just a few clicks from any of the major electronics suppliers will have the parts needed for such a project speeding on their way to your house in no time at all. But [joekutz] holds the uncontroversial belief that the value in these parts has somewhat diminishing returns, so he struck out to build his own Pi laptop with a €4 DVD player screen and a whole lot of circuit wizardry to make his parts bin laptop work.

The major hurdle that he needed to overcome was how to power both the display and the Pi with the two small battery banks he had on hand. Getting 5V for the Pi was easy enough, but the display requires 8V so he added one lithium ion battery in series (with its own fuse) in order to reach the required voltage. This does make charging slightly difficult but he also has a unique four-pole break-before-make switch on hand which doesn’t exactly simplify things, but it does make the project function without the risk of short-circuiting any of the batteries he used.

The project also makes use of an interesting custom circuit which provides low voltage protection for that one lonely lithium battery as well. All in all it’s a master course in using some quality circuit-building skills and electrical theory to make do with on-hand parts (and some 3D printing) rather than simply buying one’s way out of a problem. And the end result is something that’s great for anything from watching movies to playing some retro games.

Continue reading “A Lot Of Effort For A Pi Laptop”

Spare Parts Express

I’ve got spare parts, and I cannot lie.

This week I’m sending out two care packages to friends and coworkers because I’ve got too many hackables on hand, and not enough time to hack them all. One is a funky keyboard, and the other is an FPGA dev board, but that’s not the point. The point is that the world is too interesting, and many of us have more projects piled up in the to-do box, with associated gear, than we’ll ever have time to complete.

Back in the before-times, we would meet up, talk about our ongoing hacks, and invariably someone would say “oh you need an X, I’ve got half a box of them” and send you one. Or maybe you’d be the one with the extra widgets on hand. I know I’ve happily been in both positions.

Either way, it’s a win for the giver, who gets to take a widget off the widget pile, for the receiver, who doesn’t have to go to the widget store, and for the environment, which has to produce fewer widgets. (My apologies to the widget manufacturers and middlemen.)

This reminded me of Lenore Edman and Windell Oskay’s Great Internet Migratory Box Of Electronics Junk back in the late aughts. Trolling through the wiki was like a trip down memory lane. This box visited my old hackerspace, and then ended up with Bunnie Huang. Good times, good people, good hacker junk! And then there’s our own Brian Benchoff’s Travelling Hacker Box and spinoffs.

These are great and fun projects, but they all end up foundering in one respect: to make sense, the value of goods taken and received has to exceed the cost of the postage, and if you’re only interested in a few things in any given box, that’s a lot of dead weight adding to the shipping cost.

So I was trying to brainstorm a better solution. Some kind of centralized pinboard, where the “have too many h-bridge drivers” folks can hook up with the “need an h-bridge” people? Or is this ad-hoc social network that we already have working out well enough?

What do you think? How can we get the goods to those who want to work on them?

Ask Hackaday: How Do You Keep The 3D Printer From Becoming EWaste

One thing we sometimes forget in our community is that many of the tecniques and machines that we take for granted are still something close to black magic for many outsiders. Here’s a tip: leave a 3D printer running next time you take a group of visitors round a hackerspace, and watch their reaction as a Benchy slowly emerges from the moving extruder. To us it’s part of the scenery, but to them it’s impossibly futuristic and their minds are blown.

Just because something says it's a Prusa i3, doesn't mean it is a Prusa i3.
Just because something says it’s a Prusa i3, doesn’t mean it is a Prusa i3.

Nearly 15 years after the dawn of the RepRap project we have seen a huge advancement in the capabilities of affordable 3D printers, and now a relatively low three-figure sum will secure a machine from China that will churn out prints whose quality would amaze those early builders. We’ve reached the point in our community at which many people are on their third or fourth printer, and this has brought with it an unexpected side-effect. Where once a hackerspace might have had a single highly prized 3D printer, now it’s not unusual to find a pile of surplus older printers on a shelf. My hackerspaces both have several, and it’s a sight I’ve frequently seen on my travels around others. Perhaps it’s a sign of a technology maturing when it becomes ewaste, and thus it seems affordable 3D printing has matured. Continue reading “Ask Hackaday: How Do You Keep The 3D Printer From Becoming EWaste”

Racing Simulator Built From Scrapheap Finds

Paradise means something different for everyone, it could be a sitting by a fire on a rainy night or lying on a sun-kissed beach. But for us, and makers like [liltreat4you], it’s a well stocked scrap pile out behind the house. After buying a racing wheel and pedals for his Xbox, he took a trip out to his little slice of paradise and found nearly all the hardware he needed to build a professional looking race simulator. According to his breakdown, most of the money he spent on this build ended up going into that sweet red paint job and the speed-enhancing stickers.

Everything the light touches is our kingdom.

Not all of us are as lucky as [liltreat4you], and we probably won’t just happen upon a driver’s seat out of a Mazda, or a bunch of perfectly bent metal pipes from an old trampoline out on the back forty. But trolling Craigslist or cruising around for flea markets can still get you parts like these for cheap, so try not to be too discouraged if your backyard isn’t quite as well stocked.

Once he had the metal pipes and seat from the car, the rest of the build came together pretty quickly. After building an oval out of his salvaged pipes, he attached the seat and the arms that would eventually hold the steering wheel and display. A plate was also added at the bottom for the pedals to sit on. By using long bolts, [liltreat4you] was even able to add a degree of adjustment to the wheel position. Being that he got his seat out of a real car, there’s the usual adjustment you’d expect there as well.

Speaking of which, [liltreat4you] casually mentions that you should disconnect the battery of the donor vehicle before taking out the seat, as it’s possible that the removal of the seat or the disconnection of the seat harness can cause the airbags to deploy. We can neither confirm nor deny this, but it’s probably safe advice to follow.

The purists out there may claim that what [liltreat4you] has put together doesn’t quite meet the definition of simulator in its current form. But with the addition of some instrumentation and just a bit of physical feedback, he’ll be well on his way to the complete driving experience.

The Complex Issue Of Hackspace Donations

More than one member of the Hackaday team has significant involvement in a hackspace, as member, director, or even founder. We talk about hackspaces quite rarely on these pages though, not because we don’t have anything to say on the matter but because even when we write in general terms our fellow members invariably think it’s all about them rather than the hackspace world at large.

For once I’m going to break the silence, and not only talk about hackspaces, but talk about my own hackspace in specific terms. Because, fellow Oxford Hackspace members, this isn’t about you personally though I’m using our home to illustrate a point. The topic is a thorny issue that must affect all spaces, that of donations of physical items. People want to help their hackspace, they have a pile of what they consider to be good stuff, and when they’re having a clear-out they make a donation. But, as we all know, “one man’s trash is another man’s treasure” and vice-versa. Continue reading “The Complex Issue Of Hackspace Donations”

Too Good To Throw Away: Dealing With An Out-Of-Control Junk Hoard

There it was, after twenty minutes of turning the place over, looking through assorted storage boxes. A Thinwire Ethernet network. About the smallest possible Thinwire Ethernet network as it happens, a crimped BNC lead about 100mm long and capped at each end by a T-piece and a 50 ohm terminator. I’d been looking for a BNC T-piece on which to hook up another terminator to a piece of test equipment, and I’d found two of them.

As I hooked up the test I wanted to run I found myself considering the absurdity of the situation. I last worked somewhere with a Thinwire network in the mid 1990s, and fortunately I am likely to never see another one in my life. If you’ve never encountered Thinwire, be thankful. A single piece of co-ax connecting all computers on the network, on which the tiniest fault causes all to fail.

So why had I held on to all the parts to make one, albeit the smallest possible variant? Some kind of memento, to remind me of the Good Old Days of running round an office with a cable tester perhaps? Or was I just returning to my past as a hoarder, like a Tolkienic dragon perched atop a mountain of electronic junk, and not the good kind of junk?

Continue reading “Too Good To Throw Away: Dealing With An Out-Of-Control Junk Hoard”