Universal TFT Display Backpack Helps Small Displays Shine

June 4, 2022 by Donald Papp 16 Comments

TFT technology might be ancient news for monitors and TVs, but it’s alive and well when it comes to hobbyist electronics and embedded devices. They’ve now become even easier to integrate, thanks to the Universal TFT Display Backpack design by [David Johnson-Davies].

Breakout board, compatible with pinouts of most small TFT displays.

Such displays are affordable and easy to obtain, and [David] noticed that many seemed to have a lot in common when it came to pinouts and hookup info. The result is his breakout board design, a small and easy-to-assemble PCB breakout board that can accommodate the pinouts of a wide variety of TFT displays available from your favorite retailers or overseas sellers.

The board has a few quality-of-life features such as an optional connection for a backlight, and a staggered pin pattern so that different TFT boards can be pushed in to make a solid connection without soldering. That’s very handy for testing and evaluating different displays.

Interested? Head on over to the GitHub repository for the project, and while you’re at it, check out [David]’s Tiny TFT Graphics Library 2 which is a natural complement to the display backpack. [David] sure knows his stuff when it comes to cleverly optimized display work; we loved his solution for writing to OLED displays without needing a RAM buffer.

Gaze Inside These Nanopower Op-Amps

June 4, 2022 by Donald Papp 2 Comments

[Robo] over at Tiny Transistor Labs has a fascinating look at what’s inside these modern, ultra low-power devices that consume absolutely minuscule amounts of current. Crank up the magnification, and go take a look at the dies on these two similar (but internally very different) devices.

Texas Instruments LPV801, under the hood.

The first unit is the Texas Instruments LPV801, a single-channel op-amp that might not be very fast, but makes up for it by consuming only a few hundred nanoamps. Inside, [Robo] points out all the elements of the design, explaining how a part like this would be laser-trimmed to ensure it performs within specifications.

The second part is the Texas Instruments LPV821 which uses a wee bit more power, but makes up for it with a few extra features like zero-drift and EMI hardening. Peeking inside this device reveals the different manufacturing process this part used, and [Robo] points out things like the apparent lack of fuses for precise trimming of the part during the manufacturing process.

Seeing these structures up close isn’t an everyday thing for most of us, so take the opportunity to check out [Robo]’s photos. Tiny Transistor Labs definitely takes the “tiny” part of their name seriously, as we’ve seen with their 555 timer, recreated with discrete transistors, all crammed into a package that’s even the same basic size as the original.

DIY Keyboard Can’t Get Much Smaller

June 4, 2022 by Donald Papp 6 Comments

The PiPi Mherkin really, really can’t get much smaller. The diminutive keyboard design mounts directly to the Pi Pico responsible for driving it, has a similar footprint, and is only about 9 mm thick. It can’t get much smaller since it’s already about as small as the Pi Pico itself.

Running on the Pi Pico is the PRK firmware, a keyboard framework that makes the device appear as a USB peripheral, checking the “just works” box nicely. The buttons here look a little sunken, but the switches used are available in taller formats, so it’s just a matter of preference.

We have to admit the thing has a very clean look, but at such a small size we agree it is perhaps more of a compact macropad than an actual, functional keyboard. Still, it might find a place in the right project. Design files are online, if you’re interested.

If you like small, compact keyboards but would prefer normal-sized keys, check out the PiPi Mherkin’s big brother, the PiPi Gherkin which gets clever with dual-function tap/hold keys to provide full functionality from only 30 keys, with minimal hassle.

Keyboards are important, after all, and deserve serious attention, as our own [Kristina Panos] knows perfectly well.

3D Printed Flexure Shows Precision In Action

June 3, 2022 by Donald Papp 18 Comments

Here’s an older but fantastic video that is as edifying as it is short. [Topias Korpi] demonstrates a 3D printed flexure with a dial indicator on one end, and an M3 screw on the other. As the screw is turned, the dial indicator moves steadily with roughly a 15:1 reduction between the movement of the screw and the indicator. Stable deflections of 0.01 mm are easily dialed in, and it’s neat seeing it work while the flexure itself shows no perceptible movement. A demonstration is embedded below the page break and is less than a minute long, so give it a watch and maybe get some ideas.

Flexures are fantastic designs capable of a wide variety of physical functions, and just as [Topias]’s demonstration shows, they can be a natural complement to 3D printing. In fact, flexures are an important part of the design and function of JWST’s mirror actuators, which are responsible for making astonishingly small adjustments to each of the space telescope’s 18 mirror sections.

Continue reading “3D Printed Flexure Shows Precision In Action” →

3D Printed Protection Against “Under-Door” Attacks

June 2, 2022 by Donald Papp 44 Comments

“Under-door” style attacks are when an attacker slides a tool through the gap underneath a door, hooks the interior handle from below, and opens the door by pulling the handle downward. This kind of attack works on the sort of doors and locks commonly found in hotels, where turning the handle from the inside always results in an open door. [Michal Jirků] found himself in a hotel room with a particularly large gap underneath the door, and decided to quickly design and print a door guard to protect against just such an attack.

It’s a simple object, and twenty minutes of printing and a little double-sided tape is all it takes to deploy. Because an attacker performs an under-door attack with a sizable mechanical disadvantage, it doesn’t take much to frustrate the attempt, and that’s exactly what the object does. Physical security in hotels is especially important, after all, and crooks have been known to exploit known flaws like the face-palmingly bad Onity key card lock exploit.

If you’re having trouble picturing how it all works, this video demonstrates an under-door attack in action, so you can see how blocking the space by the handle would easily prevent the tool from getting where it needs to go.

Laser-Engraving Hairlines: When A Line Isn’t A Line

May 29, 2022 by Donald Papp 8 Comments

When is a line not a line? When it’s a series of tiny dots, of course!

The line is actually tiny, laser-etched craters, 0.25 mm center-to-center.

That’s the technique [Ed Nisley] used to create a super-fine, colored hairline in a piece of clear plastic — all part of his project to re-create a classic Tektronix analog calculator from the 1960s, but more on that in a moment.

[Ed] tried a variety of methods and techniques, including laser engraving a solid line, and milling a line with an extremely tiny v-tool. Results were serviceable, but what really did the trick was a series of tiny laser-etched craters filled in with a red marker. That resulted in what appears — to the naked eye — as an extremely fine hairline. But when magnified, as shown here, one can see it is really a series of small craters. The color comes from coloring in the line with a red marker, then wiping the excess off with some alcohol. The remaining pigment sitting in the craters gives just the right amount of color.

This is all part of [Ed]’s efforts to re-create the Tektronix Circuit Computer, a circular slide rule capable of calculating all kinds of useful electrical engineering-related things. And if you find yourself looking to design and build your own circular slide rule from scratch? We have you covered.

Adjustable Workholding For Honeycomb Tables, With A Bit Of DIY

May 29, 2022 by Donald Papp 6 Comments

Honeycomb tables are often found on laser cutters, where they provide a way for work material to be laid flat while not interfering with things like airflow. This leads to a cleaner laser cut and a nicer finish, but if one’s work depends on precise positioning and placement, they leave something to be desired because there’s no good way to attach rails, jigs, or anything of the sort in an easy and stable fashion.

The solution [Ed] found for this was to make himself some adjustable offset stops designed to fit into his laser cutter’s honeycomb table. Each consists of a laser-cut disc of wood, which is screwed off-center into an acetal “plug” sized to fit into the vertical gaps in the honeycomb table. This allows each disc to be rotated to fine-tune positioning. With the help of some T-shaped pegs that are also sized to fit into the honeycomb table, [Ed] has all he needs to fix something like a workpiece or jig into a particular and repeatable position.

The whole thing depends on a friction fit, so the sizing of the plug needs to match a particular honeycomb table’s construction. We think this makes it a good match for 3D printing, as one can measure and print plugs (perhaps employing the Goldilocks approach) that fit with just the right amount of snug.

Honeycomb tables are fantastic for laser cutting, but if you find yourself in a pinch for a replacement, an old radiator can make a pretty decent stand-in.