The green CRT display of a scanning-electron microscope is shown, displaying small particles.

DIY Calibration Target For Electron Microscopes

June 12, 2025 by Aaron Beckendorf 3 Comments

It’s a problem that few of us will ever face, but if you ever have to calibrate your scanning electron microscope, you’ll need a resolution target with a high contrast under an electron beam. This requires an extremely small pattern of alternating high and low-density materials, which [ProjectsInFlight] created in his latest video by depositing gold nanoparticles on a silicon slide.

[ProjectsInFlight]’s scanning electron microscope came from a lab that discarded it as nonfunctional, and as we’ve seen before, he’s since been getting it back into working condition. When it was new, it could magnify 200,000 times and resolve features of 5.5 nm, and a resolution target with a range of feature sizes would indicate how high a magnification the microscope could still reach. [ProjectsInFlight] could also use the target to make before-and-after comparisons for his repairs, and to properly adjust the electron beam.

Since it’s easy to get very flat silicon wafers, [ProjectsInFlight] settled on these as the low-density portion of the target, and deposited a range of sizes of gold nanoparticles onto them as the high-density portion. To make the nanoparticles, he started by dissolving a small sample of gold in aqua regia to make chloroauric acid, then reduced this back to gold nanoparticles using sodium citrate. This gave particles in the 50-100 nanometer range, but [ProjectsInFlight] also needed some larger particles. This proved troublesome for a while, until he learned that he needed to cool the reaction temperature solution to near freezing before making the nanoparticles.

Using these particles, [ProjectsInFlight] was able to tune the astigmatism settings on the microscope’s electron beam so that it could clearly resolve the larger particles, and just barely see the smaller particles – quite an achievement considering that they’re under 100 nanometers across!

Electron microscopes are still a pretty rare build, but not unheard-of. If you ever find one that’s broken, it could be a worthwhile investment.

Continue reading “DIY Calibration Target For Electron Microscopes” →

Two white, cylindrical speakers are shown. The sides and most of the tops of the speakers are covered in holes, and at the center of the top of each, there is a circular LCD display. The top of the speaker is marked “Braun.”

A Modern Take On Iconic Industrial Design

June 9, 2025 by Aaron Beckendorf 21 Comments

The Functionalist design philosophy that Dieter Rams brought to Braun from the 50s to the 90s still inspires the look of a few devices, including Apple’s iPod, Teenage Engineer’s synthesizers and recorders – and [2dom]’s IR7 streaming radio.

The streaming radio was inspired by Braun’s portable radios, particularly the SK2, TP1, and the T3 pocket radio. [2dom] started with the T3’s circular pattern of holes and experimented with several variations, finally settling on a cylindrical shape with a central display; a prototype with a low-power monochrome rectangular display was eventually rejected in favor of a circular LCD. The housing consists of four 3D-printed components: an upper and lower shell, a resonator for the speaker, and a knob for a rotary encoder.

Electronics-wise, an ESP32 handles the computing requirements, while the LCD and rotary encoder provide a user interface. For audio, it uses a VS1053 MP3 decoder, PAM8403 amplifier, and a wideband speaker, with an audio isolation transformer to clean up the audio. To reduce power consumption, a MOSFET cuts power to the peripheral components whenever the device is in sleep mode. The full design is available on GitHub.

The end result of this effort is a quite authentic-looking 21st-century adaptation of Rams’s original designs. If you’re interested in more Braun designs, check out this replica of one of their desk fans. We’ve also seen a restoration of one of Braun’s larger radios, the TS2.

The Saleae logic analyzer software is shown. One PWM channel is active, with values of 0x0001 displayed above the individual waveforms. On the right panel of the app, a trigger mode configuration panel is open for the simple parallel analyzer.

Simple Triggering For Saleae Logic Analyzers

June 8, 2025 by Aaron Beckendorf 4 Comments

Saleae logic analyzers seem to have it all: good sampling rates, convenient protocol decoding, and plenty of channels – but not a good way to set rising or falling-edge triggering. [James] found this rather inconvenient when debugging embedded devices, and shared a workaround that replicates these simple triggering modes.

Crucially, the logic analyzer’s software has a repeated triggering mode that fires when the protocol decoder detects a preset value. [James] used a clever trick to turn this into a rising-edge trigger: he set up a simple parallel analyzer, and set the signal in question as both the sampled channel and the clock signal. Since he wanted to detect the rising edge, he set the clock mode accordingly. Next, he loaded the simple parallel decoder’s trigger configuration and set it to detect a value of one, the value of a high signal. When he ran the simple parallel trigger, every rising edge of the input signal would trigger the clock to check for a high value on the line, in turn triggering the analyzer.

It’s also possible to set up a falling-edge trigger by selecting the falling-edge clock mode and setting the trigger mode to detect a value of zero. Setting up more complex triggers involving multiple channels is as simple as calculating the hexadecimal value of the desired state and setting the parallel decoder to trigger on that value. For example, if you want to trigger when one input is low and another is high, you can set the decoder to trigger on a value or one or two, depending on which order the inputs come in.

If all this makes you interested in Saleae logic analyzers, we’ve seen them used for everything from floppy disk preservation to signal generation. We’ve even reviewed their earliest model back in 2009.

Continue reading “Simple Triggering For Saleae Logic Analyzers” →

A man’s hands are shown in the foreground holding two splines, each with teeth both on the interior and exterior surfaces. Both are identical in shape, but one is larger and made of plastic, and the other is smaller and made of metal.

Freeze-drying For Improved Metal Printing

June 6, 2025 by Aaron Beckendorf 12 Comments

For all the remarkable improvements we’ve seen in desktop 3D printers, metal printers have tended to stay out of reach for hackers, mostly because they usually rely on precise and expensive laser systems. This makes it all the more refreshing to see [Dan Gelbart]’s demonstration of Rapidia’s cast-to-sinter method, which goes from SLA prints to ceramic or metal models.

The process began by printing the model in resin, scaled up by 19% to account for shrinkage. [Dan] then used the resin print to make a mold out of silicone rubber, after first painting the model to keep chemicals from the resin from inhibiting the silicone’s polymerization. Once the silicone had set, he cut the original model out of the mold and prepared the mold for pouring. He made a slurry out of metal powder and a water-based binder and poured this into the mold, then froze the mold and its contents at -40 ℃. The resulting mixture of metal powder and ice forms a composite much stronger than pure ice, from which [Dan] was able to forcefully peel back the silicone mold without damaging the part. Next, the still-frozen part was freeze-dried for twenty hours, then finally treated in a vacuum sintering oven for twelve hours to make the final part. The video below the break shows the process. Continue reading “Freeze-drying For Improved Metal Printing” →

The Pluto software-defined radio is placed on a desk, connected by three RF cables to an RF bridge circuit board. The RF bridge has a prominent ballon taking up most of its area.

Turning The Pluto SDR Into A Network Analyzer

June 5, 2025 by Aaron Beckendorf 1 Comment

Usually when we see a project using a software-defined radio (SDR), the SDR’s inputs and outputs are connected to antennae, but [FromConceptToCircuit]’s project connected an ADALM-Pluto SDR to an RF bridge and a few passive components to make a surprisingly effective network analyzer (part two of the video).

The network analyzer measures two properties of the circuit to which it is connected: return loss (S11) and insertion gain or loss (S21). To measure S21, the SDR feeds a series of tones to the device under test, and reads the device’s output from one of the SDR’s inputs. By comparing the amplitude of the input to the device’s output, a Python program can calculate S21 over the range of tested frequencies. To find S11, [FromConceptToCircuit] put an RF bridge in line with the device being tested and connected the bridge’s output to the SDR’s second input. This allowed the program to calculate the device’s impedance, and from that S11. Continue reading “Turning The Pluto SDR Into A Network Analyzer” →

A circuit board is shown, with the tip of a soldering iron applied to a piece of solder wick positioned above a pad.

Making Solder Wick Less Painful

June 4, 2025 by Aaron Beckendorf 28 Comments

For some people (e.g. this author) solder wick is a tool of last resort. Unfortunately, solder suckers and vacuum pumps lose most of their utility when you move from through-hole to SMD components, forcing us to use the dreaded wick. For those of us in this mindset, [nanofix]’s recent video which we’ve placed below the break on tips for solder wick could make desoldering a much less annoying experience.
Continue reading “Making Solder Wick Less Painful” →

A weather forecast is shown on a blue monochrome cathode ray tube display. It is displaying current conditions, and displays a “The Weather Channel” graphic in the top left corner.

A CRT Display For Retro Weather Forecasting

May 31, 2025 by Aaron Beckendorf 16 Comments

It would be hard to find any electronics still in production which use CRT displays, but for some inscrutable reason it’s easy to find cheap 4-inch CRTs on AliExpress. Not that we’re complaining, of course. Especially when they get picked up for projects like this Retro CRT Weather Display from [Conrad Farnsworth], which recreates the interface of The Weather Channel’s WeatherStar 4000+ in a suitably 90s-styled format.

The CRT itself takes up most of the space in the enclosure, with the control electronics situated in the base behind the display driver. A Raspberry Pi Zero W provides the necessary processing power, and connects to the CRT through its composite video output.

A custom PCB plugs into the GPIO header on the Raspberry Pi and provides some additional features, such as a rotary encoder for volume and brightness display, a control button, a serial UART interface, and a speaker driver. The design still has one or two caveats: it’s designed to powered by USB, but [Conrad] notes that it draws more current than USB 2.0 can provide, though USB-C should be able to keep up.

On the software side, a Python program displays a cycle of three slides: local weather, regional weather, and a radar display. For the local and regional weather display graphics, [Conrad] created a static background image containing most of the graphics, and the program only generated the dynamic components. For the radar display, the regional map’s outlines come from Natural Earth, and a Python program overlays radar data on them.