Hands On With a Batteryless E-Paper Display

E-paper displays are unusual in that power is only needed during a screen update. Once the display’s contents have been set, no power whatsoever is required to maintain the image. That’s pretty nifty. By making the display driver board communicate wirelessly over near-field communication (NFC) — which also provides a …read more

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ESP32 Becomes Music Player In Under 40 Lines of Code

The demo code for [XTronical]’s ESP32-based SD card music player is not even 40 lines long, though it will also require a few economical parts before it all works. Nevertheless, making a microcontroller play MP3s (and other formats) from an SD card is considerably simpler today than it was years …read more

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Dremel Workstation’s New Job: Applying Threaded Inserts With Cheap Soldering Iron

Dremel has been helping people fit square pegs into round holes for years, and [concretedog] saw that the Dremel 220 Workstation — a piece of hardware similar to a drill press — could be convinced to hold a cheap soldering iron just as easily as it holds a rotary tool. …read more

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External Battery Mod for Action Camera Does It Non-destructively

[Facelesstech] owns an SJCAM SJ4000 action camera, but the internal battery was no longer functional. Not wishing to buy a replacement and unwilling to hook up an ungainly USB cable to feed power, the solution was to design and 3D print an adapter to power the camera from a single …read more

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Finding Perfect Part Fits with the Goldilocks Approach (and OpenSCAD)

There is something to be said for brute force or trial-and-error approaches to problems, especially when finding a solution has an empirical element to it. [Tommy] perceived that to be the case when needing to design and 3D print servo horns that would fit factory servos as closely as possible, …read more

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Tic-Tac-Toe Implemented in Single Call to printf()

[Nicholas Carlini] programmed a C implementation of two-player Tic Tac Toe, and he did it in a single call to printf(). The arguments for that single function call get mind-bendingly complex, so it may come as no surprise that it was written for The International Obfuscated C Code Contest …read more

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Palm’s Mini-Mobile Phone Becomes Bike Phone

The mini-mobile phone [Jim Yang] got his hands on deserves a bit of background. Palm had the concept of a companion mobile phone, and this manifested itself in late 2018 as a cute palm-sized smartphone that one could carry around when one didn’t wish to haul along their “real” phone. …read more

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3D Printering: Sticky Resin Prints and How to Fix Them

After going through all the trouble of printing a part in resin, discovering it feels sticky or tacky to the touch is pretty unwelcome. Giving the model some extra ultraviolet (UV) curing seems like it should fix the problem, but it probably does not. So, what can be done?

The …read more

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Building One Test Fixture to Rule Them All

Test and programming fixtures are great time-savers for anyone who needs to deal with more than a handful of PCBs. Instead of plugging in connectors (or awkwardly holding probe tips or wires) to program some firmware or run tests, one simply pops a PCB into a custom fixture with one …read more

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Rolling Your Own LED Matrix Driver, With Copper Foil Tape to the Rescue

It all started when [Damien Walsh] got his hands on some surplus LED boards. Each panel contained 100 mini-PCBs hosting a single bright LED that were meant to be to be snapped apart as need. [Damien] had a much better idea: leave them in their 20×5 array and design a …read more

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