Summer is the season for family road trips here in the US, and my family took to the open road in a big way this year. We pulled off a cross-country relocation, from Connecticut to Idaho. Five days on the road means a lot of pit stops, and we got to see a lot of truck stops and consequently, a lot of long-haul truckers. I got to thinking about their unique lifestyle and tried to imagine myself doing that job. I wondered what I’d do hour after long hour, alone in the cab of my truck. I figured that I’d probably just end up listening to a lot of audio books, but then I realized that there’s a perfect hobby for the road — ham radio. So I decided to see how ham radio is used by truckers, and mull over how a truck driver version of me might practice The World’s Best Hobby.
[David Cook]’s summary below the write-up of his experiences working with a bismuth ingot is succinct.
“I wasted a weekend learning why elemental bismuth is not commonly used for metal parts.“
It’s a fair assessment of his time spent growing unspectacular bismuth crystals, casting a bismuth cylinder that cracked, and machining bismuth only to be left with a very rough finish. But even though he admits the exercise was unsuccessful, he does provide us with a fascinating look at the physical properties of the element.
Bismuth is one of those elements you pass by in your school chemistry lessons, it has applications in machining alloys and as a lead replacement but most of us have never knowingly encountered it in the real world. It’s one of the heavy metals, below antimony and to the right of lead on the Periodic Table. Curious schoolchildren may have heard that like water it expands on solidifying or that it is diamagnetic, and most of us have probably seen spectacular pictures of its crystals coated in colourful iridescent oxides.
It was a Hackaday story about these crystals that attracted [David] to the metal. It has a low enough melting point – 271.5 °C – that it can be liquified on a domestic stove, so mindful of his marital harmony should he destroy any kitchen appliances he bought a cheap electric ring from Amazon to go with his bismuth ingot. and set to work.
His first discovery was that cheap electric rings outdoors aren’t very effective metallurgy furnaces. Relocating to the kitchen and risking spousal wrath, he did eventually melt his bismuth and pick off the top layer once it had resolidified, to reveal some crystals.
Unfortunately for him, instead of spectacular colors and huge crystals, the sight that greeted him was one of little brilliance. Small grey crystals with no iridescence. It seems the beautiful samples are made by a very slow cooling of the liquid bismuth, followed by a quick pouring off of the remaining molten metal. Future efforts, he assures us, will involve sand-insulated molds and careful temperature monitoring.
Undeterred, he continued with his stock of bismuth and embarked on the creation of a cylinder. Early efforts with a clay mold resulted in cracked cylinders, so in desperation he cast the entirety of the metal in an aluminium baking tray and cut the resulting ingot to a rough piece of stock for turning.
With the bismuth in the lathe, he then came face to face with what he alluded to in his conclusion above, why machined bismuth parts aren’t something you’ll encounter. His cylinder came out with significantly rough patches on the surface, because bismuth is both crystalline and brittle. He suggests improvements could be made if the metal could be solidified with fewer crystals, but it’s obvious that elemental bismuth on its own is not a winner in the turning stakes.
We suggest you take a look at [David]’s write-up. It may be presented as a Fail of The Week here, but in fact it’s more of a succession of experiments that didn’t work than an unmitigated disaster. The result is an interesting and well-documented read that we’re sure most Hackaday readers will gain something from.
Aside from the bismuth crystals linked to above, we’ve featured bismuth a few times here at Hackaday. A low-temperature soldering process used it in an alloy, and we’ve even featured someone using it in another alloy to print using a RepRap.
Thanks [nebk] for the tip.
In our final installment of Tools of the Trade (with respect to circuit board assembly), we’ll look at how the circuit board is tested and programmed. At this point in the process, the board has been fully assembled with both through hole and surface mount components, and it needs to be verified before shipping or putting it inside an enclosure. We may have already handled some of the verification step in an earlier episode on inspection of the board, but this step is testing the final PCB. Depending on scale, budget, and complexity, there are all kinds of ways to skin this cat.
You would think that there’s nothing to know about RGB LEDs: just buy a (strip of) WS2812s with integrated 24-bit RGB drivers and start shuffling in your data. If you just want to make some shinies, and you don’t care about any sort of accurate color reproduction or consistent brightness, you’re all set.
But if you want to display video, encode data in colors, or just make some pretty art, you might want to think a little bit harder about those RGB values that you’re pushing down the wires. Any LED responds (almost) linearly to pulse-width modulation (PWM), putting out twice as much light when it’s on for twice as long, but the human eye is dramatically nonlinear. You might already know this from the one-LED case, but are you doing it right when you combine red, green, and blue?
It turns out that even getting a color-fade “right” is very tricky. Surprisingly, there’s been new science done on color perception in the last twenty years, even though both eyes and colors have been around approximately forever. In this shorty, I’ll work through just enough to get things 95% right: making yellows, magentas, and cyans about as bright as reds, greens, and blues. In the end, I’ll provide pointers to getting the last 5% right if you really want to geek out. If you’re ready to take your RGB blinkies to the next level, read on!
Chances are you’ve spent a lot of time trying to think of the next great project to hit your workbench. We’ve all built up a set of tools, honed our skills, and set aside some time to toil away in the workshop. This is all for naught without a really great project idea. The best place to look for this idea is where it can make life a little better.
I’m talking about Assistive Technologies which directly benefit people. Using your time and talent to help make lives better is a noble pursuit and the topic of the 2016 Hackaday Prize challenge that began this morning.
Assistive Technology is a vast topic and there is a ton of low-hanging fruit waiting to be discovered. Included in the Assistive Technology ecosystem are prosthetics, mobility, diagnostics for chronic diseases, devices for the aging or elderly and their caregivers, and much more. You can have a big impact by working on your prototype device, either directly through making lives better and by inspiring others to build on your effort.
Need some proof that this is a big deal? The winners of the 2015 Hackaday Prize developed a 3D printed mechanism that links electric wheelchair control with eye movement trackers called Eyedrivomatic. This was spurred by a friend of theirs with ALS who was sometimes stuck in his room all day if he forgot to schedule a caregiver to take him to the community room. The project bridges the existing technologies already available to many people with ALS, providing greater independence in their lives. The OpenBionics Affordable Prosthetic Hands project developed a bionic hand with a clever whiffletree system to enable simpler finger movement. This engineering effort brings down the cost and complexity of producing a prosthetic hand and helps remove some of the barriers to getting prosthetics to those who need them.
The Is the Stove Off project adds peace of mind and promotes safe independence through an Internet connected indicator to ensure the kitchen stove hasn’t been left on and that it isn’t turned on at peculiar times. Pathfinder Haptic Navigation reimagines the tools available to the blind for navigating their world. It uses wrist-mounted ultrasonic sensors and vibration feedback, allowing the user to feel how close their hands are to objects. Hand Drive is another wheelchair add-on to make wheeling yourself around a bit easier by using a rowing motion that doesn’t depend as much on having a strong hand grip on the chair’s push ring.
In most cases, great Assistive Technology is not rocket science. It’s clever recognition of a problem and careful application of a solution for it. Our community of hackers, designers, and engineers can make a big impact on many lives with this, and now is the time to do so.
Enter your Assistive Technology in the Hackaday Prize now and keep chipping away on those prototypes. We will look at the progress all of the entries starting on October 3rd, choosing 20 entries to win $1000 each and continue onto the finals. These finalists are eligible for the top prizes, which include $150,000 and a residency at the Supplyframe Design Lab, $25,000, two $10,000 prizes, and a $5,000 prize.
This is a tale of old CPUs, intensive SMD rework, and things that should work but don’t.
Released in 1994, Apple’s Powerbook 500 series of laptop computers were the top of the line. They had built-in Ethernet, a trackpad instead of a trackball, stereo sound, and a full-size keyboard. This was one of the first laptops that looked like a modern laptop.
The CPU inside these laptops — save for the high-end Japan-only Powerbook 550c — was the 68LC040. The ‘LC‘ designation inside the part name says this CPU doesn’t have a floating point unit. A few months ago, [quarterturn] was looking for a project and decided replacing the CPU would be a valuable learning experience. He pulled the CPU card from the laptop, got out some ChipQuick, and reworked a 180-pin QFP package. This did not go well. The replacement CPU was sourced from China, and even though the number lasered onto the new CPU read 68040 and not 68LC040, this laptop was still without a floating point unit. Still, it’s an impressive display of rework ability, and generated a factlet for the marginalia of the history of consumer electronics.
Faced with a laptop that was effectively unchanged after an immense amount of very, very fine soldering, [quarterturn] had two choices. He could put the Powerbook back in the parts bin, or he could source a 68040 CPU with an FPU. He chose the latter. The new chip is a Freescale MC68040FE33A. Assured by an NXP support rep this CPU did in fact have a floating point unit, [quarterturn] checked the Mac’s System Information. No FPU was listed. He installed NetBSD. There was no FPU installed. This is weird, shouldn’t happen, and now [quarterturn] is at the limits of knowledge concerning the Powerbook 500 architecture. Thus, Ask Hackaday: why doesn’t this FPU work?
Are you in New York? What are you doing this week? Hackaday is having a party on Wednesday evening. come on out!
How about a pub in Cambridge? Hackaday and Tindie will be there too, on Wednesday evening. It’s a bring-a-hack, so bring a hack and enjoy the company of your fellow nerds. If this goes late enough we can have a trans-Atlantic Hackaday meetup.
Portable emulation machines are all the rage, and [Pierre] built one based on the Raspberry Pi Zero. It’s small, looks surprisingly comfortable to hold, and is apparently it’s fairly inexpensive to build your own.
For the last year or so, the Raspberry Pi Zero has existed. This came as a surprise to many who couldn’t buy a Raspberry Pi Zero. In other news, Ferraris don’t exist, and neither do Faberge egg omelets. Now, the Raspberry Pi shortage is officially over. They’re in stock everywhere, and we can finally stop listening to people who call the Pi Zero a marketing ploy.
No Starch Press is having another Humble Bundle. Pay what you want, and you get some coding books. They have Python, Haskell, and R, because no one should ever have to use SPSS.
[Reg] wrote in to tell us about something interesting he found while cruising eBay. The used and surplus market is awash in Siemens MC45/MC46 cellular modem modules. They’re a complete GSM ‘cellular modem engine’, with an AT command set, and cost about $10 each. Interfacing them with a board requires only two (strange) connectors, SIM and SD card sockets, and a few traces to through-hole pads. Anyone up for a challenge? A breakout board for this cellular modem could be very useful, should someone find a box full of these modules in a surplus shop.
On this page, about halfway down the page, is an LCD driver board. It turns a video signal into something a small, VGA resolution LCD will understand. This driver board is unique because it is completely hand-made. This is one of those small miracles of a soldering iron and copper clad board. If anyone out there is able to recognize these parts, I’d love for you to attempt an explanation in the comments.
A few weeks ago, the RTL8710 WiFi module showed up on the usual online marketplaces. Initially, we thought it was a competitor to the ever-popular ESP8266, offering a small microcontroller, WiFi, and a bunch of useful output pins. A module based on the RTL8710, the RTL-00, is much more than a competitor. It’s pinout compatible with the ESP8266. This module can be swapped into a project in place of the ESP-12, probably the most popular version of the ESP8266. This is genius, and opens the door to a lot of experimentation with the RTL8710.