A Baby Named DJ

June 19, 2019 by Brian McEvoy 8 Comments

Some of us are guilty of picking up questionable hardware from garage sales, fleamarkets, and well-meaning relatives. There is a balance between turning down a good investment and hoarding, and if we figure out how to tell the difference you will be the first to know. [Clem Mayer] may start on the side of unwise acquisition, but he pushes a broken fetal detector into the realm of awesome by converting it to an analog synthesizer, born to headline at an Eastern European dance party.

He starts with a basic teardown, and we get to see how old hardware was serviceable with only two standard screws. It is a good thing too, because the nickel-cadmium batteries are older than some of you and they are in need of replacement. New nickel-metal hydride batteries got it up and running but [Clem] does not have a baby bump so its functionality turned to Pink Floyd era synthesizer circuit bending. Circuit bending involves modifying a circuit for sound it was not intended to make.

Continue reading “A Baby Named DJ” →

Abusing A CPU’s Adders To Optimize Bit Counting

June 19, 2019 by Al Williams 40 Comments

If you like nitpicking around C code and generated assembly language — and we’ll admit that we do — you shouldn’t miss [Scaramanga’s] analysis of what’s known as Kernighan’s trick. If you haven’t heard of the trick, it’s a pretty efficient way of counting bits.

Like the Wheatstone bridge and a lot of other things, the Kernighan trick is misnamed. Brian Kernighan made it famous, but it was actually first published in 1960 and again in 1964 before he wrote about it in 1988. The naive way to count bits would be to scan through each bit position noting how many one bits you encounter, but the problem is, that takes a loop for each bit. A 64-bit word, then, takes 64 loops no matter what it contains. You can do slightly better by removing each bit you find and stopping when the word goes to zero, but that still could take 64 cycles if the last bit you test is set.

Continue reading “Abusing A CPU’s Adders To Optimize Bit Counting” →

Hams Gone Wild: Amateur Radio Field Day 2019

June 19, 2019 by Dan Maloney 31 Comments

Of all the images that amateur radio conjures up, the great outdoors doesn’t usually figure heavily. People seem to think hams sit in a dark room at a desk heavy with radio gear, banging out Morse code into late into the night and heedless of the world outside the window. All of which sort of sounds like hard-core gaming, really.

And while that image certainly applies in a lot of cases, hams do like to get out and about at least once a year. That day is upon us with the 2019 Amateur Radio Field Day. Hams across North America reserve the fourth full weekend of each June to tear themselves out of their shacks and get into the world to set up operations in some kind of public venue, generally a park or other green space. Part cookout, part community outreach, and part slumber party – it lasts all weekend and goes around the clock – hams use field day as a chance to show the general public where amateur radio really shines: real-time worldwide communications under austere conditions.

It’s also a chance to get folks excited about getting their license, with many Field Day locations hosting “Get on the Air” stations so that unlicensed folks can try making a contact under the supervision of a licensed operator. Licensed but underequipped hams also get the chance to spin the knobs on someone else’s gear, and maybe line up that first rig purchase. And there are plenty of opportunities to learn about new modes as well, such as FT8 and WSPR. As an example your scribe is looking for some guidance on getting started with APRS, the automated packet reporting system that’s used for things like high-altitude balloon tracking.

If you have any interest at all in learning how to properly operate radio equipment, you owe it to yourself to track down the nearest Field Day location and stop by. The American Radio Relay League (ARRL) has a ton of Field Day information, from a map to locate the 1500 Field Day sites to rules for the contests that will be run that weekend to guides for setting up and operating an effective Field Day setup. There will be 40,000 hams out there this year, and they’d all be thrilled if you drop by and ask a few questions.

Continue reading “Hams Gone Wild: Amateur Radio Field Day 2019” →

Tomorrow Night: HDDG 40, Mechanical And Electronic Ephemera

June 19, 2019 by Brian Benchoff No comments

For the last several years, we’ve hosted a series of meetups for the Bay Area. This week is no different and we’re pleased to announce the fortieth Hardware Developers Didactic Galactic. It’s this Thursday, June 20th, in downtown San Francisco.

The Hardware Developers Didactic Galactic is our monthly IRL meetup, where we ask hardware developers what makes their thing tick. We’ve done dozens of these things, and for those of you in Internet-land, all the talks are available online. Even if you’re not in the Bay Area, all the talks are live streamed. Yes, you too can participate in the event, even if you’re not going to physically attend! It’s an amazing technology called ‘the Internet’ that combines real life with virtual being! It’s like [William Gibson] created some sort of virtual/hyperspace interface.

For this month’s talks, we’ll be joined by Embedded Ninja Shaun Meehan. Shaun has previously given talks that answer the question, what happens when the majority of your work blows up on the Antares space accident? You turn around and get some of your second string units on the next SpaceX launch (9 days later)! Shaun will be talking about his two 300kg robotic arms, FRED & LEFTY, and the project of replacing their 1987 era controllers. This talk includes high power electronics, FPGAs, fixed point algorithms, galvanic isolation, transistor matching, splitting transistors in half, strange position sensors, homemade 3-phase 480 in a garage, and freight LTL shipping.

The live stream for the talks will be available here. Of course, if you can make it to downtown San Francisco (a few blocks south of the Powell Muni/BART stop) we’d be happy to see you. It all goes down Thursday, July 20th, at 6:30 PM.

Trash Printer Directly Uses Recycled Plastics

June 19, 2019 by Lewin Day 23 Comments

3D printing is all well and good, but it can get expensive having to purchase roll after roll of filament. Various projects exist that attempt to take unwanted 3D prints and turn them back into filament to be used again. However, [Sam Smith] took a different path. The Trash Printer is a 3D print head that works with recycled plastic, with less intermediate processing steps.

The Trash Printer is a print head is intended to work with shredded plastics directly, rather than by first turning them back into a filament. Thus far, [Sam] has tested the Polypropylene and HDPE, and results are promising. While the prints aren’t of the same quality as using pre-prepared filament, the parts are still viable and fit for purpose.

The print head consists of an auger, along with a cartridge heater, which work together to push plastic to the print head. The head is constructed out of laser-cut parts and a few off-the-shelf components, making it easy to replicate. [Sam] has spent significant time honing the design, and has several ideas for ways in which it could be developed further. We’re eager to see how far this technology can go, and can’t wait to see what comes next. We’ve seen other attempts to recycle plastics for 3D printing, too. Expect to see further developments in this space coming thick and fast.

Making A Mediaeval Nail

June 19, 2019 by Jenny List 69 Comments

If for some reason I were to acknowledge the inevitability of encroaching middle age and abandon the hardware hacker community for the more sedate world of historical recreation, I know exactly which band of enthusiasts I’d join and what period I would specialise in. Not for me the lure of a stately home in Regency England or the Royal court of Tudor London despite the really cool outfits, instead I would head directly for the 14th century and the reign of King Edward the Third, to play the part of a blacksmith’s wife making nails. It seems apposite to pick the year 1337, doesn’t it.

The woman blacksmith forging a nail depicted in the Holkham Bible. British Library (Public domain)

Why am I so sure? To answer that I must take you to the British Library, and open the pages of the Holkham Bible. This is an illustrated book of Biblical stories from the years around 1330, and it is notable for the extent and quality of its illuminations. All of mediaeval life is there, sharply observed in beautiful colour, for among the Biblical scenes there are contemporary images of the people who would have inhabited the world of whichever monks created it. One of its more famous pages is the one that caught my eye, because it depicts a woman wearing a blacksmith’s apron over her dress while she operates a forge. She’s a blacksmith’s wife, and she’s forging a mediaeval carpenter’s nail. The historians tell us that this was an activity seen as women’s work because the nails used in the Crucifixion were reputed to have been forged by a woman, and for that reason she is depicted as something of an ugly crone. Thanks, unknown mediaeval monk, you really don’t want to know how this lady blacksmith would draw you!
Continue reading “Making A Mediaeval Nail” →

These Projects Bent Over Backward To Win The Flexible PCB Contest

June 19, 2019 by Dan Maloney 7 Comments

Back in March, the call went out: take your wiggliest, floppiest, most dimensionally compliant idea, and show us how it would be better if only you could design it around a flexible PCB. We weren’t even looking for a prototype; all we needed was an idea with perhaps a sketch, even one jotted on the legendary envelope or cocktail napkin.

When we remove constraints like that, it’s interesting to see how people respond. We have to say that the breadth of applications for flex PCBs and the creativity shown in designing them into projects was incredible. We saw everything from circuit sculpture to wearables. Some were strictly utilitarian and others were far more creative. In the end we got 70 entries, and with 60 prizes to be awarded, the odds were ever in your favor.

Now that the entries have been evaluated and the winners decided, it’s time to look over the ways you came up with to put a flexible PCB to work. Normally we list all the winners in our contest wrap-ups, but with so many winners we can’t feature everyone. We’ll just call out a few of the real standout projects here, but you really should check the list of winning projects to see the full range of what this call for flexibility brought out in our community.

Continue reading “These Projects Bent Over Backward To Win The Flexible PCB Contest” →