According to [Kelsey], transparent displays are guaranteed to make “everything feel like the future.” Unfortunately they’re hard to find, and the ones typically available are OLED and can’t make solid black colors. But as luck would have it, it’s possible to repurpose a common LCD to be sort of transparent.
A LCD uses nematic crystals that can polarize light, with the amount of polarization changing based on the electric field applied to the crystal. Light enters the front of the panel through a polarizing film, passes through the display, and then bounces off a reflective back coating. The display itself usually polarizes light in a way that matches the front polarizer. That means if you do nothing you get reflected light. However, if a part of the LCD gets an electric field, it will repolarize in such a way as to block the reflected light making the display look black in that area.
[Kelsey’s] trick is to peel off the reflector and replace it with polarizing film taken from another display. The new polarizer needs to be bigger than the display for one reason: you need to match the polarizing angle of the front film with the new back film. That means if the new film is exactly the right size, it won’t be able to rotate without leaving gaps. By starting with a larger piece, you’ll be able to rotate for maximum transparency before you stick it on.
If you’ve ever handled a chip with a really strange or highly inconvenient pinout and suspected that the reason had something to do with the inner workings, you may be interested to see [electronupdate]’s analysis of why the 4017 Decade Counter IC has such a weirdly nonintuitive pinout. It peeks into an IC design dating from the 1970s to see an example of the kind of design issues that can affect physical layout.
In the case of the 4017, once decapped and the inner workings exposed, things became more clear. Inside the chip are a bunch of flip-flops and NAND gates, laid out in a single layer. Some of the outputs (outputs 5 and 1 for example, physically on pins 1 and 2 respectively) share the same flip-flop.
The original design placed the elements in a way that made the most logical sense for routing and layout, which resulted in nice and tidy inner workings but an apparently illogical pinout. A lot of this is probably feeling familiar to anyone who has designed and routed a single-layer PCB, where being limited to one layer makes it important to get the most connections as directly near one another as possible.
Chip design has of course come a long way since the 70s, but there is forever some level of trade-off to be made between outward tidiness and inner design harmony. The next time you’re looking at a part with an apparently illogical pinout, there’s a fair chance it makes far more sense on the inside.
We all have old projects which maybe didn’t quite deliver knocking about, sometimes they gather dust for years. They have a use though, in that when you *really* need that part you can lift it from that forgotten project. That’s what [Mustie1] did with a forgotten electric bicycle project, he took its motor and used it to automate his bead roller.
A bead roller is a tool used in the world of automotive bodywork to press a bead — a continuous depression — into a piece of sheet metal. The inexpensive roller he had fitted in a bench vice, and was operated by means of a handle. Unfortunately the size of the tool meant that it was difficult to operate at the same time as rolling a precise bead, so improvement was required.
He first considered using a cordless drill, but then remembered the electric bicycle project. Its geared motor had come from an electric wheelchair and certainly possessed the right speed, but he needed a suitable sprocket. This was supplied from a scrap engine-assisted bicycle that he’d acquired, and proved to be perfect for the job. The final automated roller used the trigger controller from a cordless drill mounted in a foot switch, and the roller mounted on a stand repurposed from a piece of gym equipment. The result is a useful, and above all controllable, tool that can run a perfect bead in any shape desired on a piece of sheet metal.
Surprisingly this is the first bead roller we’ve featured here, but sheet metal work is a constant in hardware hacker projects. Read our guide to sheet metal bending, for a start.
The filaments in question are VARIOSHORE TPU and LW-PLA, both by ColorFabb. Both filaments have a blowing agent added to the formulation, which releases gas as the temperature is increased. This causes bubbles to form, creating a cellular structure, which decreases the density and increases the flexibility of the printed part. This isn’t the first time that foaming is sold as a feature, but previously it was only done for aesthetic purposes in Polymaker’s Polywood filament.
Before putting the materials through his excellent test procedures, [Stefan] first goes through the process of tuning the print settings. This can be tricky because of the foaming, which increases the effective volume of the plastic, requiring careful adjustment of the extrusion rate. Foaming in the PLA filament reached its maximum foaming at 250 C, at which its density was 44% of the unfoamed filament.
In testing the physical properties, [Stefan] found that the tensile strength and stiffness of printed parts are reduced as foaming increases, but the impact strength is improved. He concludes that the lightweight PLA can have some interesting applications because of the reduced weight and increased impact strength, with 3D printed RC aircraft being an excellent example of this. It should also be possible to change the between layers, effectively sandwiching the foamed layers between solid skins.
There’s hardly any piece of test equipment more fundamental than a volt ohm meter. Today you’re likely to have a digital one, but for most of history, these devices had real needle meters. The AVOmeter Model 8 Mark III that [Jeff Tranter] shows off had an odd banana-shaped meter. Maybe that goes with the banana plugs. You can get a closer view of this vintage piece of equipment in the video after the break.
Even the outside description of the meter is interesting. There were several unique features. For example, if the meter goes full scale a little button pops out and disconnects the probes to protect the meter. Another unusual control reversed the polarity of the leads so you didn’t have to swap them manually.
Some of the other features will be familiar to anyone who has used a good analog meter. For example, the meter movement has a mirror under the needle. This is used to make sure you are looking straight down on the needle when making readings. If you can see the reflection of the needle, then you are off to one side and will not read the precise value you are interested in.
If you only want to see the insides, [Jeff] teases you until around the six minute mark. There are no active devices and this meter is old enough to not use a printed circuit board. The AC ranges work with a transformer and germanium diodes. The rest of the circuit is mostly a bunch of resistors.
The point to point wiring always makes us wonder who built this thing sixty years ago. You can only wonder what they would think if they knew we were looking at their handiwork in the year 2020.
We see a lot of meter clocks, but it would be a shame to tear this unique meter apart for its movement. Perhaps someone should make a clock that outputs a voltage to a terminal so you could read it with your favorite meter. This instrument was probably pretty precise for its day, but we doubt it can match a modern 6.5 digit digital instrument.
The student radio society in Trondhjem owns a Flex 6500-radio, with its associated Maestro panel peripheral. This is a software defined radio, and the Maestro is a computer containing just enough of an embedded version of Windows to run its front-end software. Unfortunately for our Norwegian radio amateur friends it runs very little else, even to the extent of being unable to connect to public WiFi that requires a web log-in. This was particularly annoying as the student network does this and they’d had to create their own hotspot, so they’ve provided some details on how they were able to open it up a little to do a bit more.
At first they were cagey about the exact nature of the exploit they used to penetrate the device’s defenses, but since then they’ve published a second installment with full details. It involved gaining access to the filesystem and a terminal through a right-click menu from a web browser screen within the Maestro software, then using that access to change configuration such that it could be exposed across the network. From there they were able to treat it much as they would a normal Windows installation, including putting other software such as SmartSDR onto it.
This piece of work provides a fascinating insight into an embedded Windows device, and leaves us as usual surprised by the ease of the exploit. We’d say it’s something of a brave move for a company to ship a feature-limited product to radio amateurs of all people, a community that has been experimenting and finding whatever means to extend the capabilities of their equipment for over a hundred years. Perhaps Flexradio’s eyes are on greater things.
Have you heard the exciting news about Betelgeuse? It’s been hard to miss these days, with reports of the red supergiant star suddenly dimming, and speculation growing that the star will go supernova sometime in the next 10,000 years. But the exciting part is that astronomers have gotten together and scheduled the Betelgeuse supernova for February 21, 2020. Or at least that’s how at least a half-dozen poorly written articles make it sound. We thought that seemed odd, so we dug a bit and the real story is more complicated and more interesting. Betelgeuse is normally a variable star that goes through complex cycles of brightening and dimming. Its current dimming is unprecedented in magnitude, but the timing coincides with its normal cycle. If this dimming is just a deepening of its normal cycle, the star should start brightening again on February 21. If it doesn’t, it could mean the star is entering the next phase in its evolution. We’d love to see a star so bright it’s visible in daylight and casts shadows at night, but we’ll just have to see what happens on Friday.
One of the last two factories in the world that makes the lacquer master discs needed to make vinyl records burned to the ground last week. Luckily nobody was hurt, but it took 82 firefighters hours to get the blaze under control. It remains to be seen how this loss will impact the vinyl record market, but since the appearance of a new star in the sky has long been seen as a bad omen and a portent of doom, if Betelgeuse does go boom next week, expect to hear the hipsters gnash their teeth and rend their man-buns. In the meantime, enjoy perhaps your last look at the fascinating vinyl manufacturing process.
Rent it once, rent it for life? Apparently, at least if you rent a Ford vehicle from Enterprise and install the FordPass app on your phone. That was the experience of one Masamba Sinclair when he rented a Ford Expedition in October and found that even five months later, the app – which he never unpaired from the rental vehicle – allowed him to start and stop the car’s engine, unlock the doors, and even track its location. The same thing even happened again this month when he rented a Mustang. Ford and Enterprise might both want to rethink the security model here; leaving it up to the customer to unlink the car from the app is a recipe for disaster.
Don’t forget that we have a really interesting contest going on right now: the Train All The Things machine learning contest. With so many different machine learning platforms and frameworks available today, you can surely find a way to build something that really shines. The early entries are interesting, with everything from an intelligent bat detector to sunglasses that give you control of the world. The contest is sponsored by Digi-Key and runs through April 7, so get started on your AI masterpiece and send it in.
Speaking of Digi-Key, they’ve put together a handy list of vendors from their line card who are reporting impacts from the Covid-19 outbreak in China. We wondered about supply chain effects from the outbreak recently, and this is confirmation that we’re starting to see a pinch. As of this writing, there are 62 vendors listed, with the majority reporting impacts from the extension of the Chinese New Year holiday. We’ll stay on top of this story, and of course we continue to wish our friends in China well.
