These DIY Super Headphones Take Sound Seriously

October 1, 2023 by Donald Papp 24 Comments

[Pete Lewis] from SparkFun takes audio and comfort seriously, and recently shared details on making a customized set of Super Headphones, granting quality sound and stereo ambient passthrough, while providing hearing protection at the same time by isolating the wearer from the environment.

Such products can be purchased off the shelf (usually called some variant of “electronic hearing protection”), but every hacker knows nothing beats some DIY to get exactly the features one wants. After all, off-the-shelf solutions are focused on hearing protection, not sound quality. [Pete] also wanted features like the ability to freely adjust how much ambient sound was mixed in, as well as the ability to integrate a line-level audio source or Bluetooth input.

Early prototype of Super Headphones (click to enlarge)

On the surface the required components are straightforward, but as usual, the devil is in the details. Microphone selection, for example, required a lot of testing. A good microphone needed to be able to deal with extremely loud ambient sounds without distortion, yet still be sensitive enough to be useful. [Pete] found a good solution, but also muses that two sets of microphones (one for loud environments, and one for quieter) might be worth a try.

After several prototypes, the result is headphones that allow safe and loud band practice in a basement as easily as they provide high-quality music and situational awareness while mowing the lawn. Even so, [Pete]’s not done yet. He’s working on improving comfort by using photogrammetry to help design and 3D print custom-fitted components.

A hot tub with a smartphone in front showing real-time sensor data

ESP32 Keeps Track Of Hot Tub’s Vital Signs

October 1, 2023 by Robin Kearey 12 Comments

Like swimming pools, hot tubs need regular monitoring to ensure their water stays clean and clear. An average person might take a water quality reading once or twice a week using test strips, but such a low sampling rate obviously won’t do for a hacker. [Stephen Carey] has therefore built a hot tub monitor that checks the water quality every minute and reports it on a neat mobile dashboard.

[Stephen]’s system uses commercially available sensors that track pH levels and Oxidation-Reduction Potential (ORP), both basic measurements that indicate water quality. A second set of sensors keeps track of the temperature of the water and the outside air, which should help in finding insulation failures and keeping energy use under control.

An ESP32 reads the sensors and sends out the data through WiFi. [Stephen] programmed the ESP32 in MicroPython, using an MQTT driver to connect it to Home Assistant. By looking at the graphs generated, you can tell when someone entered the tub from a step change in pH and ORP. It’s even possible to generate alerts when any of the values drift outside their acceptable range – we can already imagine an alarm going off when someone enters without having showered first.

The system also has a calibration mode to check the sensors against a well-defined buffer solution. As with many chemical sensors, the pH and ORP probes gradually lose their active material and need to be replaced after about a year. Good ones aren’t cheap, but [Stephen] has found pretty decent low-cost alternatives on AliExpress that should be fine for a home setup.

If you also want your tub or pool to be actively managed, you’ll need a more complex system, perhaps even one that can also dispense chemicals. If your hot tub is heated by a wood fire, however, all you need is a way to alert the person tending the fire.

Overclocking Raspberry Pi 5’s SoC To 3 GHz And 1 GHz GPU

October 1, 2023 by Maya Posch 17 Comments

Overclocking computer systems is a fun way to extract some free performance, or at least see how far you can push the hardware before you run into practical limitations. The newly released Raspberry Pi 5 with BCM2712 SoC is no exception here, with Tom’s Hardware having a go at seeing how far both the CPU and GPU in the SoC can be pushed. The BCM2712’s quad Cortex-A76 CPU is normally clocked at 2.4 GHz and the VideoCore VII GPU at 800 MHz. By modifying some settings in the /boot/config.txt configuration file these values can be adjusted.

In order to verify that an overclock was stable, the Stressberry application was used, which fully loads the CPU cores. Here something like a combination of stress-ng and glxgears could also be used, to stress both the CPU and GPU. With the official actively cooled heatsink the CPU reached a temperature of 74°C with a whole board power usage of about 10 Watts. At idle this dropped to 3 Watts at 46°C. At these speeds, the multiple Raspberry Pi 5 units OCed by Tom’s Hardware were mostly stable, though one of the team’s boards experienced a few crashes. This suggests that this level of OCing could still be subject to luck of the draw, and long-term stability would have to be investigated as well.

As for the practical use cases of OCing your Raspberry Pi 5, benchmarks showed a marked uplift in compression and Sysbench benchmark scores, but OCing the GPU had no real positive impact on YouTube or 3D performance, leading even to a massive increase in dropped frames with video playback. This probably means that increasing the CPU clock may be beneficial, but OCing the GPU could be futile without also OCing the RAM frequency, if at all possible.

Realistically, the Raspberry Pi SoCs never were speed monsters, with even the Raspberry Pi 4B’s SoC being beaten handily in 2020 by a budget dual-core Intel CPU. The current Intel Alder-Lake-N-based N100 SoC has a 6 Watt TDP and boosts up to 3.4 GHz while its Xe-LP-based iGPU (with AV1 decoding support) makes for a decent gaming experience within a ~16 Watt power envelope. Clearly, any OCing of the Raspberry Pi boards is more for the challenge of it, but then so is running the latest Intel CPU at 10 GHz with liquid nitrogen cooling.

A Spinning Egg For Your Thoughts

October 1, 2023 by Danie Conradie 16 Comments

Brushless motors are fascinating devices that come in all sorts of shapes and sizes, but you’ve probably never seen one in the form of a free-spinning shiny metal egg. Created by [David Windestål], [Giacomo Di Muro], and [Chad Kapper], the Motion Zero is part top, part brushless motor, and fully mesmerizing. Tech overview video after the break.

Like the classic Tippe Top toy, an ovoid shape like this shiny metal egg will stand on its end if it’s spun fast enough. To do this, the team embedded magnets in the metal egg, effectively turning it into a rotor. An array of 4 PCB coils under a smooth concave surface serves as the stator. Because the egg is not held in position by a shaft, hall effect sensors were incorporated to determine the position of the egg, and properly control the state of the coils to keep it spinning.

Recognizing how easy it was to get lost in thought while staring at a shiny spinning egg, the rest of the device was designed with meditation in mind. The top cover is a block of aluminum machined with ripple patterns, with ball bearings that slide between the ripples as the control interface. Additional hall effect sensors on the PCB determine the position of the balls to adjust the rotation speed and shut-off timer. You can even choose to make the egg move around or remain in one position. The main controller is an ESP32 module, which reads all the hall effect sensors and controls the coils via motor drivers.

The Motion Zero has made its debut on Kickstarter and already exceeded its initial funding goal. We like the creators’ willingness to share the inner workings of a product that manages to transform a simple concept into a mesmerizing piece of engineering artistry.

We’ve seen a good bit of [David Windestål]’s has a fascination with weird tech over the years, like racing belt sanders, fire breathing waterfowl, tri and bicopters. He even built a prop anti-drone RF cannon for a movie.

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The Magic Of A Diode Sampler To Increase Oscilloscope Bandwidth

September 30, 2023 by Jenny List 25 Comments

Making an oscilloscope is relatively easy, while making a very fast oscilloscope is hard. There’s a trick that converts a mundane instrument into a very fast one, it’s been around since the 1950s, and [CuriousMarc] has a video explaining it with an instrument from the 1960s. The diode sampler is the electronic equivalent of a stroboscope, capturing parts of multiple cycle of a waveform to give a much-slowed-down representation of it on the screen. How it works is both extremely simple, and also exceptionally clever as some genius-level high-speed tricks are used to push it to the limit. We’ve put the video below the break.

[Marc] has a Keysight 100 MHz ‘scope and the sampler allows him to use it to show 4 GHz. Inside the instrument is a pair of sample-and-hold circuits using fast diodes as RF switches, triggered by very low-rise-time short pulses. Clever tricks abound, such as using the diode pair to cancel out pulse leakage finding its way back to the source. To complete this black magic, an RF-tuned stub is utilized to help filter the pulses and further remove slower components.

It’s slightly amusing to note that the Keysight 100 MHz ‘scope is now “slow” while the early sampling ‘scopes had their “fast” capabilities in that range. The same technique is still used today, in fact, you probably have one on your bench.

The sampler he’s showing us is an accessory for another instrument we’ve previously shown you his work with.

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Micro Robot Disregards Gears, Embraces Explosions

September 30, 2023 by Donald Papp 18 Comments

Researchers at Cornell University have developed a tiny, proof of concept robot that moves its four limbs by rapidly igniting a combination of methane and oxygen inside flexible joints.

The device can’t do much more than blow each limb outward with a varying amount of force, but that’s enough to be able to steer and move the little unit. It has enough power to make some very impressive jumps. The ability to navigate even with such limited actuators is reminiscent of hopped-up bristebots.

Electronic control of combustions in the joints allows for up to 100 explosions per second, which is enough force to do useful work. The prototype is only 29 millimeters long and weighs only 1.6 grams, but it can jump up to 56 centimeters and move at almost 17 centimeters per second.

The prototype is tethered, so those numbers don’t include having to carry its own power or fuel supply, but as a proof of concept it’s pretty interesting. Reportedly a downside is that the process is rather noisy, which we suppose isn’t surprising.

Want to see it in action? Watch the video (embedded below) to get an idea of what it’s capable of. More details are available from the research paper, as well.

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CNC Soldering Bot Handles Your Headers

September 30, 2023 by Jenny List 39 Comments

Soldering pin headers by hand is a tedious task, especially when your project has a huge number of them. [iforce2d] has a large number of boards with a lot of headers, and has created a rather special CNC machine to to do the job. It’s a soldering robot, controlled by LinuxCNC and you can see it below the break.

Superficially it resembles a 3D printer made in aluminium, with an X-Y movable table and a Z-direction represented by a soldering iron and solder feeder on an arm. The solder feeder uses a Bowden tube, with a 3D-printer extruder motor pushing the solder wire down a PTFE tube and finally into a fine aluminium tube from which it’s fed to the iron tip.

Though he’s done a beautiful job of it, creating the machine is not all that’s required, because the tool path requires more attention than simply moving the iron to each pin and supplying some solder. There’s a need to consider the effect of that heat, how much each pad needs, and how much neighbouring pads contribute.

We’ve had repetitive soldering tasks just like this one though not on this scale, so we can understand the tedium this machine will relieve. We can’t however help being reminded of XKCD 1319.

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