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Have You Heard Of The Liquid Powder Display?

October 12, 2024 by 10 Comments

Over the decades the technology behind flat panel displays has continuously evolved, and we’ve seen many of them come and go. Among the popular ones there are a few that never quite made the big time, usually because a contemporary competitor took their market. An example is in a recent [Wenting Zhang] video, a mystery liquid powder display. We’d never heard of it, so we were intrigued.

The first segment of the video is an examination of the device, and a comparison with similar-looking ones such as a conventional LCD, or a Sharp Memory LCD. It’s clearly neither of those, and the answer finally came after a lot of research. A paper described a “Quick response liquid powder” as a mechanism for a novel display, and thus it was identified. It works by moving black and white electrically charged powder to flip a pixel from black to white, and its operation is not dissimilar to the liquid-based e-ink displays which evidently won that particular commercial battle.

The process of identifying the driver chip and pinout should be an essential watch for anyone with an interest in display reverse engineering. After a lot of adjusting timing and threshold voltages the dead pixels and weird effects fall away, and then it’s possible to display a not-too-high-quality image on this unusual display, through a custom PCB with an RP2040. Take a look at the video below the break.

We’ve seen [Wenting Zhang]’s work here a few times before, most recently in a very impressive mirror-less camera project.

Continue reading “Have You Heard Of The Liquid Powder Display?” →

Photochromic Dye Makes Up This Novel Optical Memristor

October 10, 2024 by 20 Comments

Despite being much in the zeitgeist lately, we have to confess to still being a bit foggy about exactly what memristors are. The “mem” part of their name seems to be the important bit, implying a memory function, but the rest of the definition seems somewhat negotiable — enough so that you can make a memristor from a bit of photochromic dye.

Now, we’ll leave the discussion of whether [Markus Bindhammer]’s rather complex optical memory cell officially counts as a memristor to the comments below, and just go through the technical details here. The heart of this experimental device is a photochromic dye known as cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene, mercifully shortened to CMTE, which has the useful property of having two stable states. Transitioning from the open state to the closed state occurs when UV light shines upon it, while switching back to the closed state is accomplished with a pulse of green light. Absent the proper wavelength of light, both states are stable, making non-volatile information storage possible.

To accomplish this trick, [Markus] filled a quartz cuvette with a little CMTE-doped epoxy resin. Inside a light-tight enclosure, two lasers — one at 405 nm wavelength, the other at 532 nm — are trained on the cuvette through a dichroic mirror. On the other side of the CMTE resin, he placed a VEML7700 high-accuracy ambient light sensor. An Arduino Nano reads the light sensor and controls the lasers. Writing and erasing are accomplished by turning on the proper laser for a short amount of time; reading the state of the cell involves a carefully timed pulse from the 405 nm laser followed by a 532 nm pulse and watching the output of the sensor.

Is a one-bit memory device that uses a dye that goes for €300 per gram and a pair of laser diodes practical? Of course not, but it’s still pretty cool, and we appreciate all the effort and expense [Markus] went to with this one. Now, if you want some fuel for the “It’s not a memristor” fire, memristors might not even be a thing.

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3D Printed Bearings With Filament Rollers

October 9, 2024 by 24 Comments

Commodity bearings are a a boon for makers who to want something to rotate smoothly, but what if you don’t have one in a pinch? [Cliff] of might have the answer for you, in the form of 3D printed bearings with filament rollers.

With the exception of the raw filament rollers, the inner and outer race, roller cage and cap are all printed. It would also be possible to design some of the components right into a rotating assembly. [Cliff] makes it clear this experiment isn’t about replacing metal bearings — far from it. Instead, it’s an inquiry into how self-sufficient one can be with a FDM 3D printer. That didn’t stop him from torture testing the design to its limits as wheel bearings on an off-road go-cart. The first version wasn’t well supported against axial loads, and ripped apart during some more enthusiastic maneuvers.

[Cliff] improved it with a updated inner race and some 3D printed washers, which held up to 30 minutes of riding with only minimal signs of wear. He also made a slightly more practical 10 mm OD version that fits over an M3 bolt, and all the design files are downloadable for free. Cutting the many pieces of filament to length quickly turned into a chore, so a simple cutting jig is also included.

Let us know in the comments below where you think these would be practical. We’ve covered some other 3D printed bearing that use printed races, as well as a slew bearing that’s completely printed. Continue reading “3D Printed Bearings With Filament Rollers” →

Need High-Power Li-Ion Charging? How About 100 W

October 4, 2024 by 21 Comments

Ever want a seriously powerful PCB for charging a Li-Ion pack? Whatever you want it for, [Redherring32] has got it — it’s a board bearing the TPS25750D and BQ25713 chips, that lets you push up to 100 W into your 1S Li-Ion pack through the magic of USB Power Delivery (USB-PD).

Why do you need so much power? Well, when you put together a large amount of Li-Ion cells, this is how you charge it all at once – an average laptop might charge the internal battery at 30 W, and it’s not uncommon for laptop batteries to be dwarfed by hackers’-built packs.

A 4-layer creation peppered with vias, this board’s a hefty one — it’s not often that you see a Li-Ion charger designed to push as much current as possible into a cell, and the chips are smart enough for that. As far as the onboard chips’ capabilities go, the board could handle pack configurations from 1S to 4S, and even act as a USB-PD source — check the IC configuration before you expect to use it for any specific purpose.

Want a simpler charger, even if it’s less powerful? Remember, you can use PPS-capable PD chargers for topping up Li-Ion packs, with barely any extra hardware required.

Makerpipe Turns Conduit Into Structures

September 27, 2024 by 25 Comments

At the risk of stating the obvious, building big things can be difficult. Sure, parts that fit on the bed of a 3D printer are easy to make, if not particularly fast, and scaling up from there is possible. But if you need a long beam or structural element, printing makes little sense; better to buy than build in that case. The trouble then becomes, how do you attach such parts together?

Enter Makerpipe. This South Carolina company, recently out of a crowdfunding campaign, makes a range of structural connectors and fittings for electrical mechanical tubing, or EMT, the galvanized steel conduit used in the electrical trades. EMT is widely available in multiple sizes and is relatively cheap, although we have noticed that the price here has ticked up quite a bit over the last couple of years. It also has the advantage of being available off-the-shelf at any big-box home improvement store, meaning you have instant access to a fantastic building material.

Makerpipe’s bolt-together couplings let you turn pieces of EMT, easily cut with a hacksaw or pipe cutter, into structures without the need for welding. Yes, you can do the same with extruded aluminum, but even if you’re lucky enough to live near a supply house that carries extrusions and the necessary fittings and is open on Saturday afternoon, you’ll probably pay through the nose for it.

Makerpipe isn’t giving their stuff away, and while we normally don’t like to feature strictly commercial products, something that makes building large structures easier and faster seems worth sharing with our community. We’ve done our share of fabricobbling together EMT structures after all, and would have killed for fittings like these.

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Supercon 2024: Last Call For Display Tech Exhibit

September 13, 2024 by 2 Comments

During this year’s Hackaday Supercon, the Supplyframe DesignLab will be playing host to a unique exhibit that catalogs the evolution of display technology. That means showcasing the best and most interesting examples they can find, from the vintage to the ultra-modern. Where are all these wonderful toys coming from, you might ask? Why, the Hackaday community, of course.

This is a rare chance to show off your prized gadgetry to a captive audience of hackers and makers. Whether it’s a custom display you’ve created or some gonzo piece of hardware you’ve been holding onto for years, now’s the time to haul it out. However, there are only a few days left to submit your display for potential inclusion, so if you’ve got something you want the Hackaday community to see, make sure you fill out the form before the September 16th deadline. That’s Monday, if you were wondering.

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Why Have Seven Segments When You Can Have 21?

September 10, 2024 by 35 Comments

IO user [monte] was pointed towards an 1898 display patent issued to a [George Mason] and liked the look of the ‘creepy’ font it defined. The layout used no less than 21 discrete segments to display the complete roman alphabet and numerals, which is definitely not possible with the mere seven segments we are all familiar with. [monte] then did the decent thing and created a demonstration digit using modern parts.

For the implementation, [monte] created a simple PCB by hand (with an obvious mistake) and 3D-printed an enclosure and diffuser to match. After a little debugging, a better PCB was ordered from one of the usual overseas factories. There isn’t a schematic yet, but they mention using a CH32V003 Risc-V micro, which can be seen sitting on the rear of the PCB.

Maximum flexibility is ensured by storing every glyph as a 32-bit integer, with each LED corresponding to a single bit. It’s interesting to note the display incorporates serifs, which are definitely optional, although you could display sans-serif style glyphs if you wanted to. There is now a bit of a job to work out how to map character codes to glyph codes, but you can have a go at that yourself here. It’s still early doors on this project, but it has some real potential for a unique-looking display.

We love displays—every kind. Here’s a layout reminiscent of a VFD digit but done purely mechanically. And if you must limit yourself to seven digits, what about this unique thing?

Continue reading “Why Have Seven Segments When You Can Have 21?” →