[James Stanley] likes to spend time making puzzles and gadgets for escape rooms, and decided for a change to try their hand at a bit of magic. The idea was to construct a ‘magic box’, in which a coin can be placed in one of a number of slots, and then be able to remotely be able to determine the slot by means unseen. Obviously, this is an electronics hack, with a neat package of sensor and radio comms hidden inside a stack of CNC-milled wood. Coin locations are transmitted via Bluetooth to a Bangle.js smartwatch, which vibrates according to the slot occupied, allowing [James] to predict where the coin was placed. Continue reading “The Egyptian Coin Box ‘Trick’”→
In a way, an e-paper display makes an excellent foundation for a reprogrammable RFID card. The display only needs power during a refresh, and 125 kHz RFID tags are passive in the sense that the power for the RFID transaction comes from the reader itself. [Georgi Gerganov] has put those together in the GGtag, an open-source project for a 3.52″ e-paper badge with a trick or two up its sleeve.
One clever function is that it is programmable with sound, a feature built off another project of [Georgi]’s called ggwave, a data-to-sound (and vice-versa) framework that has been ported to just about every hardware platform one cares to imagine — including mobile phones — and can reliably send data through the air.
Transmitting data over sound is limited in throughput but has a number of advantages, not least of which is the huge range of compatible devices. There’s a web-based tool for programming the GGtag with sound available at ggtag.io that will give you a preview and let you hear how it works. The data encoding method gives transmissions a charming beep-boop quality that’s a bit reminiscent of an analog modem handshake. GGtag can also be programmed over USB serial, a faster (but somewhat less exciting) option.
The project’s GitHub repository contains GGtag’s code and technical details, and the CrowdSupply project is in the works for anyone who would prefer to buy one once they become available.
When first starting an electronics project, it’s not uncommon to dive right in to getting the core parts of the project working. Breadboarding the project usually involves working with a benchtop power supply of some sort, but when it comes to finalizing the project the actual power supply is often glossed over. It’s not a glamorous part of a project or the part most of us want to be working with, but it’s critical to making sure projects don’t turn up with mysterious issues in the future. We can look to some others’ work to simplify this part of our projects, though, like this power supply from [hesam.moshiri].
The power supply is designed around a switch-mode topology known as a flyback converter. Flyback converters work by storing electrical energy in the magnetic field of a transformer when it is switched on, and then delivering that energy to the circuit when it is switched off. By manipulating the switching frequency and turns ratios of the transformer, the circuit can have an arbitrary output voltage. In this case, it is designed to take 220V AC and convert it to 8V DC. It uses a simplified controller chip to decrease complexity and parts count, maintains galvanic isolation for safety, and is built to be as stable as possible within its 24W power limitation to eliminate any potential issues downstream.
For anyone trying to track down electrical gremlins in a project, it’s not a bad idea to take a long look at the power supply first. Any noise or unwanted behavior here is likely to cause effects especially in projects involving sensors, ADC or DAC, or other low-voltage or sensitive components. The schematic and bill of materials are available for this one as well, so anyone’s next project could use this and even make slight adjustments to change the output voltage if needed. And, if this is your first introduction to switched-mode power supplies, check out this in-depth look at the similar buck converter circuit to better understand what’s going on behind the scenes on these devices.
Over the years, we’ve seen a good number of interfaces used for computer monitors, TVs, LCD panels and other all-things-display purposes. We’ve lived through VGA and the large variety of analog interfaces that preceded it, then DVI, HDMI, and at some point, we’ve started getting devices with DisplayPort support. So you might think it’s more of the same. However, I’d like to tell you that you probably should pay more attention to DisplayPort – it’s an interface powerful in a way that we haven’t seen before.
By [Belkin+Abisys], CC BY-SA 3.0The DisplayPort (shortened as DP) interface was explicitly designed to be a successor to VGA and DVI, originating from the VESA group – an organization created by multiple computer-display-related players in technology space, which has previously brought us a number of smaller-scale computer display standards like EDID, DDC and the well-known VESA mount. Nevertheless, despite the smaller scale of previous standards, DisplayPort has since become a hit in computer display space for a number of reasons, and is more ubiquitous than you might realize.
You could put it this way: DisplayPort has all the capabilities of interfaces like HDMI, but implemented in a better way, without legacy cruft, and with a number of features that take advantage of the DisplayPort’s sturdier architecture. As a result of this, DisplayPort isn’t just in external monitors, but also laptop internal displays, USB-C port display support, docking stations, and Thunderbolt of all flavors. If you own a display-capable docking station for your laptop, be it classic style multi-pin dock or USB-C, DisplayPort is highly likely to be involved, and even your smartphone might just support DisplayPort over USB-C these days. Continue reading “DisplayPort: A Better Video Interface”→
The only thing better than getting your hands on a repairable piece of hardware is actually finding the thing in the first place, which is why we love this “official” repair logo created by [Yves Parent]. Our predilection for crossed wrenches had (almost) nothing to do with it.
We’ve got a soft spot for logos that work well on dark web pages.
Designed to mimic the ubiquitous “Recycle” logo, [Yves] originally created the icon for Repair Café Roeselare — but realizing that it had wide practical applications, he got the OK to put it up on GitHub for others to use. Whether you’re a hobbyist creating your first PCB or a pro designing a commercial product for a particularly forward-thinking client, slapping this logo on signifies that your creation is destined for better things than the scrap heap.
[Yves] has helpfully provided the logo in both vector format (SVG) and PNG, the latter at several scales for your convenience. We’d love to see it offered in various production and CAD formats as well, so it can be dropped into as many projects as possible. So if you end up creating a DXF or STL version, be sure to submit a pull request.
While getting others onboard with this logo is just a ground roots effort currently, who knows what the future may bring? Today we take it for granted, but the official open source hardware “gear” logo has only been around for about a decade.
Cross-pollination between different industries can yield interesting innovations, and a few years ago [John Wiltrout] developed some non-slip meter probe adapters. He recently used our tips line to share some details that you won’t see elsewhere, letting us know how the idea came to be.
It started with [John] being frustrated by issues that will sound familiar: probes did not always want to stay in place, and had a tendency to skid around at the slightest provocation. This behavior gets only more frustrating as boards and components get smaller. John was also frustrated by the general inability to reliably probe through barriers like solder masking, oxidation, and conformal treatments on circuit boards. Continue reading “Dentist Tool Hardware Inspires Non-Slip Probe Tips”→
It may not exactly be what [Princess Leia] used to beg [Obi-Wan] for help, but this Star Wars-inspired volumetric display is still a pretty cool hack, and with plenty of extra points for style.
In some ways, [Maker Mac]’s design is a bit like a 3D printer for images, in that it displays slices of a solid model onto closely spaced planar surfaces. Sounds simple enough, but there are a lot of clever details in this build. The main component is a lightly modified LCD projector, a DLP-based machine with an RGB color wheel. By removing the color wheel from the projector’s optical path and hooking its sync sensor up to the control electronics, [Mac] is able to increase the framerate of the display, at the cost of color, of course. Other optical elements include a mirror to direct the projected images upwards, and a shutter harvested from an old pair of 3D TV glasses. Continue reading “A Volumetric Display With A Star Wars Look And Feel”→
