Author: Aaron Beckendorf

190 Articles

A man's hand is seen adjusting a lever connected to a lens, which is pointing down towards the windings of a small motor. A screen behind this shows an image of the windings, taken from an angle slightly to the side.

Building A Microscope With A 3D View

October 18, 2026 by 4 Comments

As electronic components grow ever smaller, a microscope has become an increasingly indispensable tool for any fine work; when inspecting electronics, though, especially solder joints, [Corebb] found a top-down view too limiting, so he built his own microscope with a rotating side-angle view.

The microscope itself is made of a commercial C-mount microscope lens assembly and a USB camera; the lens has a variable magnification factor up to 200x, which is plenty for electronics work, and is mounted on an adjustable stand to move the focal point. This is paired with an LED ring for illumination and two polarizing filters, one mounted on the lens and one one the lighting ring; when adjusted to 90 degrees from each other, these eliminate glare from reflective surfaces.

To view subjects from the side, [Corebb] built a snap-on adapter. This uses a pair of mirrors to capture a view from the side of the object and direct this through the main microscope lens. An additional concave lens compensates for the increased length of the optical path, and ball bearings let the whole adapter rotate around the microscope and capture the subject from any angle. [Corebb] tried 3D-printing the adapter, but found that flexing caused too much jitter; in addition to being sturdier, a machined aluminium part reduced shadows by allowing for thinner supports. The adapter snaps onto the microscope with small magnets, which keep the optical path consistently aligned.

This isn’t the first time we’ve seen a soldering microscope with a view from the side, but this does look much more affordable. If you’d like to try the polarized light source with your microscope, we’ve covered that before.

A waterfall display is shown, with a prominent yellow block in the upper right corner of the display.

Turning A Wi-Fi Adapter Into An SDR

October 18, 2026 by 8 Comments

Since the discovery of an undocumented I/Q sampling feature in ESP32 chips about two weeks ago, there’s been a flood of similar features being found in other wireless chips, including LoRa and Wi-Fi chipsets. The latest chip to join their ranks is the MediaTek MT7921AU, often used in Wi-Fi adapters, with two different projects developing independent SDR drivers for it in the last few days.

The first was BirriaSDR, which discovered that the chip exposes raw I/Q samples for debugging and calibration; BirriaSDR instead streams these to the host at 40 Msps in 14-bit resolution, with the option to tune from 2156 to 2610 MHz. BirriaSDR uses libusb to directly communicate with the Wi-Fi adapter and access its registers; it doesn’t make any permanent firmware changes, so the Wi-Fi adapter goes back to its original state after being used as an SDR. BirriaSDR implements an API similar to the RTL-SDR’s.

Mtk79ICAP, by contrast, exposes the MT7921AU’s sampling features over a standard SoapySDR interface. Unlike BirriaSDR, it applies some firmware changes to the chip, and it requires a modified driver to work. However, it can reach a maximum bandwidth of 80 MHz and tune to the 5 GHz bands. The Wi-Fi adapter in use can also simultaneously work in monitor mode and stream SDR data, though this only works when automatic gain control is enabled.

This is the second MediaTek chip we’ve seen repurposed for SDR work, after the earlier MT7996. Conveniently, Wi-Fi adapters often have external antennas, which should make it easier to connect a frequency mixer circuit. These adapters aren’t quite there yet, but some hackers have already used the ESP32 to transmit arbitrary signals.

A PCB layout is superimposed on a grey grid of hexagonal cells. The PCB traces mostly bend at 120-degree angles, and an integrated circuit's footprint is tilted at an angle matching the grid.

Improving An Autorouter With A Hexagonal Grid

October 11, 2026 by 11 Comments

Despite the recent leaps forward in other forms of computer-driven design, the reliability of PCB autorouters remains questionable; on the positive side, though, the lack of massive training data makes them plausible for a determined programmer to implement. For anyone contemplating this undertaking, [James Bowman] recommends a slightly unusual choice: use a hexagonal layout grid.

[James] built his own autorouter in his CuFlow PCB layout program. It takes a fairly straightforward approach: it represents the board as a grid of cells, and uses Lee’s algorithm to find the shortest routes between connected cells. The program initially used a square grid, but a hexagonal grid had a few advantages: in particular, each cell has six equidistant neighbors, rather than four (or eight, if you accept diagonal neighbors at a different distance), which allows denser routing. Because a hexagon more closely approximates a circle than a square, the same minimum-distance rules allow smaller cells, allowing the autorouter to pack more traces into the same space.

While we have previously seen a self-built autorouter, it’s much more common to interface with an external tool. If you start to get into high-speed PCB routing, though, building an autorouter becomes much harder.

A man's arm is shown against a mountainous backdrop. The man is wearing a black watch with an orange segment on one side.

Restoring An Altimeter Watch To Former Heights

October 10, 2026 by No comments

Finding inexpensive broken hardware for sale, buying it, and restoring it to working condition is a long-standing tradition for hackers on a limited budge. But there are some devices that are so difficult to repair that it’s usually not worth the trouble. [Vintage560] is braver than most, though, and restored an internally-damaged Casio AW-330-AT altimeter watch.

The exterior of the watch was in good condition, other than missing a readily-replaced strap, but the battery had leaked into the interior, and the watch didn’t respond in any way to new batteries. Cleaning out the guts with isopropyl alcohol, repositioning a plastic insulator, and bending some contacts back into shape at least got some segments of the LCD display to activate, while over two days of turning the crown smoothed out resistance in the analog train.

Actually getting the LCD to work properly required disassembling the watch, taking particular care with the altitude sensor. It wasn’t clear what was wrong with the LCD — the controller seemed to be working properly, and several rounds of cleaning and adjusting the ZEBRA connector didn’t make any difference.

Eventually, [Vintage560] simply purchased a new screen. On close inspection, it looked as though chemicals from the leaking battery might have dissolved some of the transparent indium tin oxide contacts on the old display. With the watch now working [Vintage560] tested it on a trip to the Alps, and with a few periodic calibrations, it remained quite accurate.

Usually when we see Casio watch hacks, the watch in question is the F91W, whether it’s being used for contactless payments, being retrofitted as a smartwatch, or going 5,000 meters underwater.

A pair of red, articulated, 3D printed hands are being used to pour water from a plastic bottle into a glass. One hand holds the bottle, and one holds the glass.

Building A Cheap, Dexterous Robot Hand

October 5, 2026 by 10 Comments

Most of the time, assuming nothing’s gone wrong with them, we take our hands so much for granted that it’s easy to forget what remarkable pieces of engineering they are: not only are they precise and sensitive enough to crack an egg or write a signature, but also strong enough to lift a weight or swing a hammer. Such performance has thus far eluded robot hands, but fortunately few tasks require it; the main challenge is dexterity, which is where [Vittorio Lumare]’s low-cost Yeah Hand could help.

The Yeah Hand is mostly 3D-printed and uses five servo motors per hand; like a human hand, it has no actuators within the fingers themselves, instead using fishing-line tendons to transfer motion from the motors. To reduce friction and keep the motors from overheating, each tendon runs through guides made from PTFE Bowden tubes; in tests, the hand ran 800 cycles of opening and closing without even getting close to overheating. The hand can lift up to eight kilograms and apply a maximum grasping force of five kg. For better grip, each finger has silicone grips along the inner surface, which let it hold smooth objects quite steady; to pick up fine objects, the thumbs have thumbnails.

Continue reading “Building A Cheap, Dexterous Robot Hand” →

A dark optical bench is shown, with a lens in the right-hand part of the image. In front of the image, a bright blue spark appears in the air, with no equipment near it.

Upgrading A Benchtop Laser For Megawatt Power

October 4, 2026 by 7 Comments

One fascinating thing about a pulsed laser is that, though the average power may be measured in watts or milliwatts, the peak power can easily reach millions of times that. This happens even in normal operation, but as [Les’ Lab] demonstrated, adding a Q-Switch can considerably enhance the peak power.

A Q-switch is an optical attenuator; when placed in the laser cavity, it keeps the cavity from reaching resonance. This greatly limits stimulated emission, allowing energy to build up in the chamber as the gain medium becomes increasingly saturated. Eventually, at some energy level, the Q-switch suddenly stops blocking light, and the cavity lases in a very short, powerful pulse. The Q-switch doesn’t increase the energy in a laser shot, but it does release it much more quickly. In this case, [Les] used chromium-doped yttrium aluminum garnet crystals as the Q-switch and compared performance across several different crystals.

Continue reading “Upgrading A Benchtop Laser For Megawatt Power” →

A drone is shown, carrying underneath it a white plastic box. On the side of the box are two patch antennas. A camera extends from one end of the box, and a large GPS antenna from the other end.

Synthetic Aperture Radar Drone Gets Interferometric Imaging

September 28, 2026 by 10 Comments

It’s been more than a year since [Henrik Forstén] built the first iteration of his synthetic-aperture radar (SAR) imaging drone, and he’s certainly been productive in the meantime. Not only did he develop a much more powerful autofocus algorithm to clean up the radar images, but he also extended the software to create high-resolution interferometric images.

The main limitation of the original radar system was the GPS, which only had a resolution of about one meter; the autofocus algorithm owed much of its improved clarity to an improved estimation of the drone’s position. A simpler, though more expensive, solution was to add an RTK-capable GPS receiver. RTK (Real-Time Kinematic) receivers use a fixed ground station to constantly transmit a correction signal, letting them reach a couple centimeters of accuracy. Since the drone doesn’t actually need to know its position in real time, it can also use PPK (Post-Processing Kinematic) positioning, which compares recorded GPS signals after the flight to obtain similarly accurate positions.

[Henrik] also implemented a few other hardware improvements, including stabilizing the phase-locked loop used to generate the radar’s frequency sweep. The controller FPGA’s SD card interface had too low a bandwidth to record data in real time, so [Henrik] also implemented a simple, fast compression algorithm to speed that up. Most significantly, he also developed a program for interferometric imaging. The drone flies the same path twice at different altitudes; by comparing phase information from different passes, it’s possible to detect a target’s elevation. Normally, the radar program assumes constant elevation, making tall objects seem to lean toward the radar source; an interferogram, on the other hand, allowed [Henrik] to generate a detailed elevation map.

[Henrik] is no stranger to synthetic aperture radar; we’ve previously covered a bike-mounted iteration and a budget SAR system. If the concepts behind this are still a bit fuzzy, we’ve also covered a guide to making your own SAR setup.