Raspberry Pi Simulates The Real Analog TV Experience

If you’ve laid hands on a retro analog TV, have the restoration bug, and you plan to make the final project at least somewhat period-correct, you face a bit of a conundrum: what are you going to watch? Sure, you can serve up just about any content digitally these days, but some programs just don’t feel right on an old TV. And even if you do get suitably retro programming, streaming isn’t quite the same as the experience of tuning your way through the somewhat meager selections as we did back in the analog days.

But don’t worry — this Raspberry Pi TV simulator can make your streaming experience just like the analog TV experience of yore. It comes to us from [Rodrigo], who found a slightly abused 5″ black-and-white portable TV that was just right for the modification. The battery compartment underneath the set made the perfect place to mount a Pi, which takes care of streaming a variety of old movies and shorts. The position of the original tuning potentiometer is read by an Arduino, which tells the Pi which “channel” you’re currently tuned to.

Composite video is fed from the Pi’s output right into the TV’s video input, and the image quality is just about what you’d expect. But for our money, the thing that really sells this is the use of a relay to switch the TV’s tuner back into the circuit for a short bit between channel changes. This gives a realistic burst of static and snow, just like we endured in the old days. Hats off to [Rodrigo] for capturing everything that was awful about TV back in the day — Mesa of Lost Women, indeed! — but still managing to make it look good.

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Wire race bearing

Adding Wire Races Improves 3D-Printed Bearings

Like a lot of power transmission components, bearings have become far easier to source than they once were. It used to be hard to find exactly what you need, but now quality bearings are just a few clicks away. They’re not always cheap though, especially when you get to the larger sizes, so knowing how to print your own bearings can be a handy skill.

Of course, 3D-printed bearings aren’t going to work in every application, but [Eros Nicolau] has a plan for that. Rather than risk damage from frictional heating by running plastic or metal balls in a plastic race, he uses wire rings as wear surfaces. The first video below shows an early version of the bearing, where a pair of steel wire rings lines the 3D-printed inner and outer races. These worked OK, but suffered from occasional sticky spots and were a bit on the noisy side.

The second video shows version two, which uses the same wire-ring race arrangement but adds a printed ball cage to restrain the balls. This keeps things quieter and eliminates binding, making the bearing run smoother. [Eros] also added a bit of lube to the bearing, in the form of liquid PTFE, better known as Teflon. It certainly seemed to smooth things out. We’d imagine PTFE would be more compatible with most printed plastics than, say, petroleum-based greases, but we’d be keen to see how the bearings hold up in the long term.

Maybe you recall seeing big 3D-printed bearings around here before? You’d be right. And we’ve got you covered if you need to learn more about how bearings work — or lubricants, for that matter.

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Electroplating Carbon Fibers Can Have Interesting Results

Typically, electroplating is used to put coatings of one metal upon another, often for reasons of corrosion protection or to reduce wear. However, other conductive materials can be electroplated, as demonstrated by [Michaɫ Baran].

Finer details are sparse, but [Michaɫ’s] images show the basic concept behind producing a composite metal material hand sculpture. The initial steps involve 3D printing a perforated plastic shell of a hand, and stuffing it with carbon fibers. It appears some kind of plastic balls are also used in order to help fill out the space inside the hand mold.

Then, it’s a simple matter of dunking the plastic hand in a solution for what appears to be copper electroplating, with the carbon fiber hooked up as one of the electrodes. The carbon fibers are then knitted together by the copper attached by the electroplating process. The mold can then be cut away, and the plastic filling removed, and a metal composite hand is all that’s left.

[Michaɫ] has experimented with other forms too, but the basic concept is that these conductive fibers can readily be stuffed into molds or held in various shapes, and then coated with metal. We’d love to see the results more closely to determine the strength and usefulness of the material.

Similar techniques can be used to strengthen 3D printed parts, too. If you’ve got your own ideas on how to best use this technique, sound off below. If you’ve already done it, though, do drop us a line!

[Thanks to Krzysztof for the tip]

A MetaSense joystick

3D-Printing Complex Sensors And Controls With Metamaterials

If you’ve got a mechatronic project in mind, a 3D printer can be a big help. Gears, levers, adapters, enclosures — if you can dream it up, a 3D printer can probably churn out a useful part for you. But what about more complicated parts, like sensors and user-input devices? Surely you’ll always be stuck buying stuff like that from a commercial supplier. Right?

Maybe not, if a new 3D-printed metamaterial method out of MIT gets any traction. The project is called “MetaSense” and seeks to make 3D-printed compliant structures that have built-in elements to sense their deformation. According to [Cedric Honnet], MetaSense structures are based on a grid of shear cells, printed from flexible filament. Some of the shear cells are simply structural, but some have opposing walls printed from a conductive filament material. These form a capacitor whose value changes as the distance between the plates and their orientation to each other change when the structure is deformed.

The video below shows some simple examples of monolithic MetaSense structures, like switches, accelerometers, and even a complete joystick, all printed with a multimaterial printer. Designing these structures is made easier by software that the MetaSense team developed which models the deformation of a structure and automatically selects the best location for conductive cells to be added. The full documentation for the project has some interesting future directions, including monolithic printed actuators.

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3D-Printed Press-Forming Tools Dos And Don’ts

Press-forming is a versatile metal forming technique that can quickly and easily turn sheet metal into finished parts. But there’s a lot of time and money tied up in the tooling needed, which can make it hard for the home-gamer to get into. Unless you 3D-print your press-form tooling, of course.

Observant readers will no doubt recall our previous coverage of press-forming attempts with plastic tooling, which were met with varying degrees of success. But [Dave]’s effort stands apart for a number of reasons, not least of which is his relative newbishness when it comes to hot-squirt manufacturing. Even so, he still came up with an interesting gradient infill technique that put most of the plastic at the working face of the dies. That kept print times in the reasonable range, at least compared to the days of printing that would have been needed for 100% infill through the whole tool profile.

The other innovation that we liked was the idea to use epoxy resin to reinforce the tools. Filling the infill spaces on the tools’ undersides with resin resulted in a solid, strong block that was better able to withstand pressing forces. [Dave] didn’t fully account for the exothermic natures of the polymerization reaction, though, and slightly warped the tools. But as the video below shows, even suboptimal tools can perform, bending everything he threw at them, including the hydraulic press to some extent.

It sure seems like this is one technique to keep in mind for a rainy day. And hats off to [Dave] for sharing what didn’t work, since it points the way to improvements.

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Remoticon Video: How To 3D Print Onto Fabric With Billie Ruben

We’re impressed to see the continued flow of new and interesting ways to utilize 3D printing despite its years in the hacker limelight. At the 2020 Hackaday Remoticon [Billie Ruben] came to us from across the sea to demonstrate how to use 3D printing and fabric, or other flexible materials, to fabricate new and interesting creations. Check out her workshop below, and read on for more detail about what you’ll find.

The workshop is divided into two parts, a hands-on portion where participants execute a fabric print at home on their own printer, and a lecture while the printers whirr away describing ways this technique can be used to produce strong, flexible structures.

The technique described in the hands on portion can be clumsily summarized as “print a few layers, add the flexible material, then resume the printing process”. Of course the actual explanation and discussion of how to know when to insert the material, configure your slicer, and select material is significantly more complex! For the entire process make sure to follow along with [Billie]’s clear instructions in the video.

The lecture portion of the workshop was a whirlwind tour of the ways which embedded materials can be used to enhance your prints. The most glamourous examples might be printing scales, spikes, and other accoutrement for cosplay, but beyond that it has a variety of other uses both practical and fashionable. Embedded fabric can add composite strength to large structural elements, durable flexibility to a living hinge, or a substrate for new kinds of jewelry. [Billie] has deep experience in this realm and she brings it to bear in a comprehensive exposition of the possibilities. We’re looking forward to seeing a flurry of new composite prints!

PET 2001 Emulator On $2 Of Hardware

Since the late 60s, Moore’s law has predicted with precision that the number of semiconductors that will fit on a chip about doubles every two years. While this means more and more powerful computers, every year, it also means that old computers can be built on smaller and cheaper hardware. This project from [Bjoern] shows just how small, too, as he squeezes a PET 2001 onto the STM32 Blue Pill.

While the PET 2001 was an interesting computer built by Commodore this project wasn’t meant to be a faithful recreation, but rather to test the video output of the Blue Pill, with the PET emulation a secondary goal. It outputs a composite video signal which takes up a good bit of processing power, but the PET emulation still works, although it is slightly slow and isn’t optimized perfectly. [Bjoern] also wired up a working keyboard matrix as well although missed a few wire placements and made up for it in the software.

With his own home-brew software running on the $2 board, he has something interesting to display over his composite video output. While we can’t say we’d emulate an entire PC just to get experience with composite video, we’re happy to see someone did. If you’d like to see a more faithful recreation of this quirky piece of computing history, we’ve got that covered as well.

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