A brown plastic circuit board is visible in the middle of the picture, containing an integrated circuit, a resistor, a diode, two capacitors, and some jumper wires going away to the sides.

A Solderless, Soluble Circuit Board

August 19, 2025 by 25 Comments

Anyone who’s spent significant amounts of time salvaging old electronics has probably wished there were a way to take apart a circuit board without desoldering it. [Zeyu Yan] et al seem to have had the same thought, and designed circuit boards that can be dissolved and recycled when they become obsolete. Read the details in the research paper. (PDF)

The researchers printed the circuit boards out of water-soluble PVA, with hollow channels in place of interconnects. After printing the boards, they injected a eutectic gallium-indium liquid metal alloy into these channels, populated the boards with components, making sure that their leads were in contact with the liquid alloy, and finally closed off the channels with PVA glue, which also held the components in place. When the board is ready to recycle, they simply dissolve the board and glue in water. The electric components tend to separate easily from the liquid alloy, and both can be recovered and reused. Even the PVA can be reused: the researchers evaporated the solution left after dissolving a board, broke up the remaining PVA, and extruded it as new filament.
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Open-Source, Flexible E-Reader

August 3, 2025 by 30 Comments

Although the most popular e-reader by far is the Kindle, some argue that its primary use isn’t even as an e-reader at all but rather as a storefront for one of the world’s richest companies. For those who want user-focused consumer electronics instead, we’ll often reach for something more untethered, like an off-brand ebook that’s nothing more than an Android tablet with an e-paper display or even a jailbroken Kindle freed from the chains of Amazon. But as our 555 enthusiast community continually points out, even these are overkill for reading books. Enter the ZEReader.

The ZEReader started out as a bachelor’s engineering thesis project by [Anna-Lena Marx], whose goal was an open-source, microcontroller-based e-reader instead of the Linux or Android ones most commonly available. She’s based the firmware around the Zephyr Real-Time Operating System, which is an RTOS geared towards embedded devices. With this as a backbone, it’s trivially easy to implement the e-reader on different microcontrollers as well as use a wide variety of screens. Although the firmware is a work-in-progress, it’s already mature enough to support all of the basics of an e-reader, such as reading .epub files, navigating through the book, and saving progress. It even includes basic HTML parsing.

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Rapid Prototyping PCBs With The Circuit Graver

November 6, 2024 by 27 Comments

Walking around the alley at Hackaday Supercon 2024, we noticed an interesting project was getting quite a bit of attention, so we got nearer for a close-up. The ‘Circuit Graver’ by [Zach Fredin] is an unconventional PCB milling machine, utilizing many 3D printed parts, the familiar bed-slinger style Cartesian bot layout and a unique cutting head. The cutting tool, which started life as a tungsten carbide lathe tool, is held on a rotary (‘R’) axis but can also move vertically via a flexure-loaded carriage driven by a 13 kg servo motor.

The stocky flexure took a lot of iteration, as the build logs will show. Despite a wild goose chase attempting to measure the cutting force, a complete machine solution was found by simply making everything stiff enough to prevent the tool from chattering across the surface of the FR4 blank. Controlling and maintaining the rake angle was a critical parameter here. [Zach] actually took an additional step, which we likely wouldn’t have thought of, to have some copper blanks pre-fabricated to the required size and finished with an ENIG coating. It’s definitely a smart move!

To allow the production of PCB-class feature sizes compatible with a traditional PCB router, the cutting tool was sharpened to a much smaller point than would be used in a lathe using a stone. This reduced the point size sufficiently to allow feature sizes down to 4 mils, or at least that’s what initial characterization implied was viable.  As you can see from the build logs, [Zach] has achieved a repeatable enough process to allow building a simple circuit using an SMT 74HC595 and some 0402 LEDs to create an SAO for this year’s Supercon badge. Neat stuff!

We see a fair few PCB mills, some 3D printed, and some not. Here’s a nice one that fits in that former category. Milling PCBs is quite a good solution for the rapid prototyping of electronics. Here’s a guide about that.

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Supercon 2023: Jesse T. Gonzalez Makes Circuit Boards That Breathe And Bend

July 24, 2024 by 5 Comments

Most robots are built out of solid materials like metal and plastic, giving them rigid structures that are easy to work with and understand. But you can open up much wider possibilities if you explore alternative materials and construction methods. As it turns out, that’s precisely what [Jesse T. Gonzalez] specializes in.

Jesse is a PhD candidate at Carnegie Mellon’s Human-Computer Interaction Institute, and an innovator to boot. His talk at the 2023 Hackaday Supercon covers his recent work on making circuit boards that can breathe and bend. You might not even call them robots, but his creations are absolutely robotic.

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The FPC adapter shown soldered between the BGA chip and the phone's mainboard, with the phone shown to have successfully booted, displaying an unlock prompt on the screen

IPhone 6S NVMe Chip Tapped Using A Flexible PCB

March 3, 2024 by 3 Comments

Psst! Hey kid! Want to reverse-engineer some iPhones? Well, did you know that modern iPhones use PCIe, and specifically, NVMe for their storage chips? And if so, have you ever wondered about sniffing those communications? Wonder no more, as this research team shows us how they tapped them with a flexible printed circuit (FPC) BGA interposer on an iPhone 6S, the first iPhone to use NVMe-based storage.

The research was done by [Mohamed Amine Khelif], [Jordane Lorandel], and [Olivier Romain], and it shows us all the nitty-gritty of getting at the NVMe chip — provided you’re comfortable with BGA soldering and perhaps got an X-ray machine handy to check for mistakes. As research progressed, they’ve successfully removed the memory chip dealing with underfill and BGA soldering nuances, and added an 1:1 interposer FR4 board for the first test, that proved to be successful. Then, they made an FPC interposer that also taps into the signal and data pins, soldered the flash chip on top of it, successfully booted the iPhone 6S, and scoped the data lines for us to see.

This is looking like the beginnings of a fun platform for iOS or iPhone hardware reverse-engineering, and we’re waiting for further results with bated breath! This team of researchers in particular is prolific, having already been poking at things like MITM attacks on I2C and PCIe, as well as IoT device and smartphone security research. We haven’t seen any Eagle CAD files for the interposers published, but thankfully, most of the know-how is about the soldering technique, and the paper describes plenty. Want to learn more about these chips? We’ve covered a different hacker taking a stab at reusing them before. Or perhaps, would you like to know NVMe in more depth? If so, we’ve got just the article for you.

We thank [FedX] for sharing this with us on the Hackaday Discord server!

Simple CMOS Circuit Allows Power And Data Over Twisted-Pair Wiring

November 21, 2023 by 29 Comments

If you need to send data from sensors, there are plenty of options, including a bewildering selection of wireless methods. Trouble is, most of those protocols require a substantial stack of technology to make them work, and things aren’t much easier with wired sensors either. It doesn’t have to be that complicated, though, as this simple two-wire power-and-data interface demonstrates.

As with all things electronic, there are tradeoffs, which [0033mer] addresses in some detail in the video below. The basic setup for his use case is a PIC-based sensor — temperature, for this demo — that would be mounted in some remote location. The microcontroller needs to be powered, of course, and also needs to send a signal back to a central point to indicate whether the monitored location is within temperature specs. Both needs are accommodated by a single pair of wires and a tiny bit of additional circuitry. On one end of the twisted pair is a power supply and decoder circuit, which sends 9 volts up the line to power the PIC sensor. The decoder is based on a CD4538 dual monostable multivibrator, set up for an “on” time of one second. A trigger input is connected to the power side of the twisted pair going to the sensor, where a transistor connected to one of the PIC’s GPIO pins is set up to short the twisted pair together every half-second. Power to the PIC is maintained by a big electrolytic and a diode, to prevent back-feeding the controller. The steady 0.5-Hz stream of pulses from the sensor keeps resetting the timer on the control side. Once that stream stops, either through code or by an open or short condition on the twisted pair, the controller triggers an output to go high.

It’s a pretty clever system with very simple and flexible circuitry. [0033mer] says he’s used this over twisted-pair wires a couple of hundred feet long, which is pretty impressive. It’s limited to one bit of bandwidth, of course, but that might just be enough for the job. If it’s not, you might want to check out our primer on current-loop sensors, which are better suited for analog sensors but still share some of the fault-detection features.

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All About USB-C: Example Circuits

August 7, 2023 by 8 Comments

In the six months that have passed after the last USB-C article has been released, I have thought up a bunch of ways that these articles could have been improved. It’s, of course, normal to have such a feeling — expected, even. I now believe that there’s a few gaps that I could bridge. For instance, I have not provided enough example circuits, and sometimes one schematic can convey things better than a thousand words.

Let’s fix that! I’ll give you schematics for the kinds of USB-C devices you’re actually likely to want to build. I’ll also share a bunch of IC part numbers in this article, but I don’t have an exhaustive collection, of course – if you find more cool ICs that work for USB-C purposes and aren’t mentioned here, please do let us all know in the comments!

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