The Splice Must Flow

There are plenty of electronic components out there, but the one we tend to forget is the most basic: wire. Sure, PC boards have largely replaced wire with copper traces, but most projects still need some kind of wire somewhere. Once you need any wire, there’s a good bet you will need longer wire, and that means splicing one wire to another. Simple, right? Not really. There are a variety of ways to splice wires, and which one you use depends on what you want to do and the type of wire you are using.

If the wires touch, good enough, right? Not necessarily. You need enough contact area for the current you are drawing through the wire to flow. It is also nice if the splice can survive some amount of mechanical strain, vibration, and survive getting hot and cold repeatedly.

Usually, after splicing, you’d like to solder the connection, although depending on the application, you don’t always see that. At the very least, you’d want to wrap it in electrical tape, use heat-shrink tubing, or otherwise insulate the bare wires and maybe provide a little mechanical support or strain relief.

Keep in mind that there are connector options, either mechanical, crimped, or soldered, that allow you to avoid splices. Soldering to a terminal strip, for example, or scewing wires into a barrier strip will get the job done. So will a butt connector, a wire nut, or a WAGO connector. But sometimes, for whatever reason, you just need to attach two wires to each other. It’s been done before.

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Fluidic Contact Lens Treats Glaucoma

We’ve always been interested in fluidic computers, a technique that uses moving fluids to perform logic operations. Now, Spectrum reports that researchers have developed an electronics-free contact lens that monitors glaucoma and can even help treat it.

The lens is made entirely of polymer and features a microfluidic sensor that can monitor eye pressure in real time. It also has pressure-activated drug reservoirs that dispense medicine when pressure exceeds a fixed threshold. You can see Spectrum’s video on the device below.

This isn’t the first attempt to treat glaucoma, which affects more than 80 million people, with a contact lens. In 2016, Triggerfish took a similar approach, but it used electronic components in the lens, which poses problems for manufacturing and for people wearing them.

Naturally, the device depends on 3D printed molds to create channels and reservoirs in the lens. A special silk sponge in the reservoirs can absorb up to 2,700 times its weight. One sponge holds a red fluid that is forced by pressure into a serpentine microchannel. A phone app uses a neural network to convert the image of the red fluid into a pressure reading.

Two more sponges hold drugs that release at a given pressure determined by the width of the associated microchannel. This allows the possibility of increasing the dose at a higher pressure or even delivering two drugs at different pressure levels.

It is fairly hard to hack your own contact lenses, although we’ve seen it at least once. But smart contacts are not as rare as you might think.

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The Kentucky Cave Wars, And Going Viral In 1925

Floyd Collins, the unfortunate star of this post. (Public Domain)

Information, it seems, flows at the speed of media. In the old days, information traveled with people on ships or horses, so if, say, a battle was won or lost, it could be months or even years before anyone back home knew what happened. While books and movable type let people store information, they still moved at the speed people moved. Before the telegraph, there were attempts to use things like semaphores to speed the flow of information,  but those were generally limited to line-of-sight operations. Carrier pigeons were handy, but don’t really move much faster than people.

The telegraph helped, but people didn’t have telegraph stations in their homes. At least not ordinary people. But radio was different. It didn’t take long for every home to have a radio, and while the means of broadcasting remained in the hands of a few, the message could go everywhere virtually instantly. This meant news could go from one side of the globe to the other in seconds. It also meant rumors, fads, and what we might think of today as memes could, too.

You might think that things “going viral” is a modern problem, but, in reality, media sensations have always been with us. All that changes is the number of them and their speed.

One of the earliest viral media sensations dealt with William Floyd Collins, an unfortunate man who was exploring caves during the Kentucky Cave Wars.

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Robot Bird Decoys Work For Good

Usually, you think of bird decoys as being a tool to lure birds to an untimely encounter with a hunter. However, [Interesting Engineering] has a story about robotic bird decoys in Grand Teton National Park that are helping restore the dwindling number of sage grouse in the park.

While some decoys are static, others are motorized to replicate mating rituals. The goal: lure real birds to safer areas to breed. Particularly, they want the birds to avoid areas around the Jackson Hole Airport. The robots are built with help from local students and robotics teams. While some of the construction is made of fabric and foam, actual bird feathers are also used.

The robots mimic lekking behavior, a courtship ritual where male grouse do repetitive motions combined with recorded mating calls. This attracts other grouse and, of course, results in chicks who will be raised nearby.

Assuming the effort is successful, the same technique could help other areas where restored areas are difficult to repopulate. You can find more pictures on the Park’s Instagram, and the title picture is from that collection.

Usually, when we see something like this, the robot is trying to remove something dangerous to the endangered plant or animal, not attract them.

A Look At Full Spectrum 3D Printing

Many modern desktop 3D printers include the ability to print in multiple colors. However, this typically only works with a few colors at a time, and the more colors you can use, the higher the machine’s cost and complexity. However, a recent technique allows printers to mix new colors by overlaying thin sheets of different filaments. [YGK3D] looks at how it works in a recent video.

In the early days of 3D printing, there were several competing approaches. You could have separate extruders, each with a different color. Some designs used a single extruder and switched between different filaments on demand. Others melted different filaments together in the hot end.

One advantage of the hotends that melted different materials is that you could make different colors by adjusting the feed rates of the plastics. However, that has its own problems with maintaining flow rate, and you can’t really use multiple material types. But using single or multiple hotends that take one filament at a time means you can only handle as many colors as you have filaments. You can’t mix, say, white and black to get gray.

Using Full Spectrum, you can define virtual filaments, and the software figures out how to approximate the color you want by using thin layers of different colors. The results are amazing. While this technically could work on any printer, in reality, a filament-switching printer will create a ton of waste to mix colors, and a single-filament machine will drive you batty manually swapping filament.

So you probably really need a tool changer and translucent plastic. You can see the difference in the test article when using opaque filament vs translucent ones. At low layer heights, four filament colors can give you 39 different colors. At more common layer heights, you may have to settle for 24 different colors.

One issue is that the top and bottom surfaces don’t color well. However, a new plugin that adds texture to the surfaces may help overcome that problem.

We looked at Full Spectrum earlier, but development continues. If you are still trying to get a handle on your filament-switching printer, we can help.

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A 6502 All In The Data

Emulating a 6502 shouldn’t be that hard on a modern computer. Maybe that’s why [lasect] decided to make it a bit harder. The PG_6502 emulator uses PostgreSQL. All the CPU resources are database tables, and all opcodes are stored procedures. Huh.

The database is pretty simple. The pg6502.cpu table has a single row that holds the registers. Then there is a pg6502.mem table that has 64K rows, each representing a byte. There’s also a pg6502.opcode_table that stores information about each instruction. For example, the 0xA9 opcode is an immediate LDA and requires two bytes.

The pg6502.op_lda procedure grabs that information and updates the tables appropriately. In particular, it will load the next byte, increment the program counter, set the accumulator, and update the flags.

Honestly, we’ve wondered why more people don’t use databases instead of the file system for structured data but, for us, this may be a bit much. Still, it is undoubtedly unique, and if you read SQL, you have to admit the logic is quite clear.

We can’t throw stones. We’ve been known to do horrible emulators in spreadsheets, which is arguably an even worse idea. We aren’t the only ones.

Your Own Tool Changer

All the cool new 3D printers have tool-changing heads. Instead of multiplexing filament through one hot end, you simply park one hot end and pick up another. Or pick up a different tool, depending on what you need. There are many advantages to a system like that, but one disadvantage: cost. [Ultimate Tool Changer] has been working on a design for what he calls a simple, cheap changer, and it appears to be working well, as you can see in the video below.

This is one of those things that seems easy until you try to do it. He talks about a lot of the failures and dead ends along the way.

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