PCB Makes 7 Segment Displays

Of course, there’s nothing unusual about using 7-segment displays, especially in a clock. However, [Edison Science Corner] didn’t buy displays. Instead, he fabricated them from a PCB using 0805 LEDs for the segments. You can see the resulting clock project in the video below.

While the idea is good, we might have been tempted to use a pair of LEDs for each segment or used a diffuser to blur the LEDs. The bare look is nice, but it can make reading some numerals slightly confusing.

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Exploded version of the Cistercian display

Serial Cistercian Digit Module

There’s no doubt that the 7-segment display is a gold standard for displaying lighted digits. But what about a throwback to an older system of displaying numbers — Cistercian? With thirty-one 0805 LEDs, [Josue Alejandro] made a simple module displaying a single Cistercian digit (any from 0-9999).

The first iteration used castellated edges and required a significant number of GPIO, so on the next rev, he switched to a serial-to-parallel converted from Lumissil (IS31FL3726A). A diffuser and spacer were printed from PLA and made for an incredibly snazzy-looking package.

Of course, it couldn’t stop there, and a third revision was made that uses SK6812 Neopixels, allowing full RGB capability. All the design documents, layout files, and incredibly detailed drawings are available on GitHub. What makes this incredibly handy is having a module you can easily add to a project. Perhaps even as a component in an escape room in a box that would allow you to flash multiple numbers. Or perhaps as a stylish clock. We’d even go so far as to challenge someone to create a calculator by combining several of these modules with this keypad.

Quick Tip Improves Seven-Segment LED Visibility

We’re suckers for a nice seven-segment LED display around these parts, and judging by how often they seem to pop up in the projects that come our way, it seems the community is rather fond of them as well. But though they’re cheap, easy to work with, and give off that all important retro vibe, they certainly aren’t perfect. For one thing, their visibility can be pretty poor in some lighting conditions, especially if you’re trying to photograph them for documentation purposes.

The tint film can be cut to size once applied.

If this is a problem you’ve run into recently, [Hugatry] has a simple tip that might save you some aggravation. With a scrap piece of automotive window tint material, it’s easy to cut a custom filter that you can apply directly to the face of the display. As seen in the video, the improvement is quite dramatic. The digits were barely visible before, but with the added contrast provided by the tint, they stand bright and beautiful against the newly darkened background.

[Hugatry] used 5% tint film for this demonstration since it was what he already had on hand, but you might want to experiment with different values depending on the ambient light levels where you’re most likely to be reading the display. The stuff is certainly cheap enough to play around with — a quick check seems to show that for $10 USD you can get enough film to cover a few hundred displays. Which, depending on the project, isn’t nearly as overkill as you might think.

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Teardown: VTech Smart Start

Regular readers may be aware that I have a certain affinity for vintage VTech educational toys, especially ones that attempted to visually or even functionally tie in with contemporary computer design. In the late 1980s, when it became obvious the personal computer was here to stay, these devices were seen as an affordable way to give kids and even young teens hands-on time with something that at least somewhat resembled the far more expensive machines their parents were using.

Much Smarter: VTech PreComputer 1000

A perfect example is the PreComputer 1000, released in 1988. Featuring a full QWERTY keyboard and the ability to run BASIC programs, it truly blurred the line between toy and computer. In fact from a technical standpoint it wasn’t far removed from early desktop computers, as it was powered by the same Zilog Z80 CPU found in the TRS-80 Model I.

By comparison, the Smart Start has more in common with a desktop electronic calculator. Even though it was released just two years prior to the PreComputer 1000, you can tell at a glance that it’s a far more simplistic device. That’s due at least in part to the fact that it was aimed at a younger audience, but surely the rapid advancement of computer technology at the time also played a part. Somewhat ironically, VTech did still at least attempt to make the Smart Start look like a desktop computer, complete with the faux disk drive on the front panel.

Of course, looks can be deceiving. While the Smart Start looks decidedly juvenile on the outside, that doesn’t mean there aren’t a few surprising technical discoveries lurking under its beige plastic exterior. There’s only one way to find out.

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RGB LED Shutter Shades

[splat238] is back at it again with another cool RGB LED display project. We were contemplating whether or not our readers have had enough of these over the last few weeks, but we’ve learned over the years that you can never have too many LED projects.

Instead of making a cool mask like we’ve covered before, [splat238] decided to trick-out some shutter shades. What’s really cool is he used the PCB itself as the frame, similar to another hack we’ve seen, which we’re sure also made his design process that much more convenient.

[splat238] got his boards pre-assembled since it would be really difficult to solder all those LEDs by hand. There are 76 of them in this design. It’s pretty helpful that he walks the reader through how to get the boards assembled, providing information on reliable fabrication and assembly houses that he’s had good experiences with. Pretty solid information if you don’t already have a go-to one-stop-house or have never designed for assembly before.

The glasses use an ESP8266-based microcontroller since it has plenty of space for storing LED patterns and has the potential benefit of including WiFi control in later revisions. However, we think you’ll be pretty happy with simply toggling through the patterns with a simple pushbutton.

The LEDs use a whopping 2.5 A at maximum and rely on an external power bank, so you’ll probably want to be really careful wearing this over an extended period of time. Maybe consider doing a bit of PWM to help reduce power consumption.

Another cool project [splat238]! Keep them coming. Continue reading “RGB LED Shutter Shades”

A Face Mask That’s Functional And Hacker-Certified

[splat238] needed a mask for going out in public, but wanted something that fit his personal style a bit better than the cloth masks everyone else was wearing. So, he upcycled his old airsoft mesh mask using an impressive 104 NeoPixels to create his NeoPixel LED Face Mask.

The NeoPixels are based on the popular WS2812b LEDs. These are individually addressable RGB LEDs with a pretty impressive glow. [splat238] purchased a 144 NeoPixel strip to avoid having to solder each of those 104 NeoPixels one-by-one. He cut the 144-LED strip into smaller segments to help fit the LEDs around the mask. He then soldered the power and data lines together so that he could still control the LEDs as if they were one strip and not the several segments he cut them into. He needed a pretty bulky battery pack to power the whole thing. You can imagine how much power 104 RGB LEDs would need to run. We recommend adding a battery protection circuit next time as these LEDs probably draw a hefty amount of current.

He designed his own controller board featuring an ESP8266 microcontroller. Given its sizable internal memory, the ESP8266 makes it easy to store a variety of LED patterns without worrying about running out of programming space. He’s also hoping to add some WiFi features in later revisions of his mask, so the ESP8266 is a no-brainer. Additionally, his controller board features three pushbuttons that allow him to toggle through different LED patterns on the fly.

Cool project [splat238]! Looking forward to the WiFi version.

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Teardown: Cobra XRS 9740 Radar Detector

Drivers with a lead foot more often than not have Waze open on their phone so they can see if other drivers have spotted cops up ahead. But avoiding a speeding ticket used to involve a lot more hardware than software. Back before the smartphone revolution, that same driver would have had a radar detector on their dashboard. That’s not to say the gadgets are completely unused today, but between their relatively high cost (one of the top rated models on Amazon as of this writing costs over $300) and the inevitable false positives from so many vehicles on the road having their own radar and LIDAR systems, they’ve certainly become a less common sight over the years

The subject of today’s teardown is a perfect example of “Peak Radar Detector”. Manufactured back in 2007, the Cobra XRS 9740 would have been a fairly mid-range entry offering the sort of features that would have been desirable at the time. Over a decade ago, having an alphanumeric display, voice alerts, and a digital compass were all things worth shouting about on the box the thing was sold in. Though looking like some kind of Cardassian warship was apparently just an added bonus.

As the name implies these devices are primarily for detecting radar activity, but by this point they’d also been expanded to pick up infrared lasers and the strobe beacons on emergency vehicles. But false positives were always a problem, so the device allows the user to select which signals it should be on the lookout for. If you were getting some kind of interference that convinced the detector it was being bombarded with IR lasers, you could just turn that function off without having to pull the plug entirely.

But it’s important to remember that this device was built back when people were still unironically carrying around flip phones. Detecting laser and multi-band radars might sound like something pulled from the spec sheet of a stealth fighter jet, but this is still a piece of consumer electronics from more than a decade in the past. So let’s crack it open and take a look at what goes on inside a radar detector that’s only a few years away from being old enough to get its own driver’s license.

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