Kritik sah

Detail of the lead connecting to the inner carbon-filled tube. (Credit: CuriousMarc) Although resistors are hardly among the most exciting components, they are arguably one of the most important ones, as anyone who has done any amount of circuit design and debugging can attest to. So too with a single carbon resistor in a vintage Metrix oscilloscope that [CuriousMarc] recently repaired. After recapping the board there was still a major issue that got traced down to said resistor. After replacing it with a fresh resistor obviously this meant doing an autopsy to see why the old resistor had failed . The 20 kOhm-rated resistor looked fine on the outside, with no obvious damage or discoloration, but it measured around 0.843 MOhm. To get to the insides [CuriousMarc] asked his friend [TubeTime] on how to proceed. The answer here was sandpaper and a lot of patience, and thus the experiment to see how much sanding it takes to get to the core of a fairly big resistor commenced. Ultimately th...

One simple screening tool for cognitive impairment is the clock-drawing test (CDT): the patient is provided with a printed circle and asked to draw a clock face with the hands pointing to a certain time. Depending on how the clock is drawn, this could indicate a variety of different disorders, particularly dementia, with a particular deformity in the drawing sometimes pointing to a specific issue. These failed tests inspired [John Silvia] to create a clock with a unique, disordered face. The numerals in this clock face are placed exclusively along the right half of the clock (in the test, this can be a sign of damage to the right parietal lobe, or of executive dysfunction caused by dementia), and out of order. The hour hand is controlled by a servo motor, and the minute hand is mounted on a separate, commercially-purchased clock mechanism on the left-hand side of the face. The frame for the clock and the face are 3D-printed, and the servo motor is controlled by an ESP32-C3 with an ...

It seems fair to say that Dyson sits at the intersection of impressive engineering and borderline ridiculous products. The Dyson Airblade 9KJ hand dryer that [ElectrArc240] recently took to bits would definitely seem to fall under the latter, combining an incredible amount of engineering all for the simple task of drying wet hands. These hand dryers are rated for a cool 900 Watts, with an 0.5 W standby power consumption, though you can also switch it to a 650 W ‘eco mode’ when installing it. The air that gets sucked into the dryer first passes through a HEPA filter before it hits the heating element and then gets blown out of the handles onto one’s hands. Both of these handles come with a presence sensor in the form of an ST VL53L3CX time-of-flight sensor, along with a path for the heated air towards the thin slits. Returning to the section just past the HEPA filter is the compressor, with a rather fancy airflow path that involves various stacked meshes. As can be ...

In some parts of the world it’s common for cell service providers to sell new phones at a price significantly below market value, with the caveat that these phones are locked to that service provider alone. It’s questionable whether this practice is good for consumers, but as [Gabriel Broussard Korr] notes, it’s an opportunity for hackers: since it’s possible to run a Linux environment on these phones, they make an inexpensive source of quite powerful computing hardware. In this case, [Gabriel] was using the Moto G Power 2024, which has 128 GB of storage, 12 GB of RAM, and costs less than $50 when carrier-locked. Rather than trying to install a mobile-oriented Linux distribution (such as postmarketOS ), [Gabriel] installed Termux, a terminal emulator which provides a Linux environment within Android. Before doing this, he set up the phone and configured a number of settings for a better Linux experience. Since automatic updates can interfere with these settings, and since none ...

We’ve covered etch-a-sketch robots before, but usually they’re not quite as fast as [Every Flavor of Robot]’s “video” etch-a-sketch , capable of drawing a full portrait in as little as a minute. The robot, nearly finished drawing a portrait of [William Osman] The idea comes from the motivation to make something cool for Open Sauce. Of course, most projects with a deadline come very close to missing it, and–like many an Open Sauce project–this one is no exception. Arriving in California, they realize they couldn’t access their code! Fortunately, they get a demo working where your portrait is drawn just in time. After the event, [EFoR] sought to improve their robot. In doing so, they developer their own motor driver platform , complete with a custom PCB that can double as a Raspberry Pi hat. The software, being control theory, also needed some tweaking. Because the real world isn’t perfect, just a PID controller isn’t always...

The Honeywell X2S Smart Thermostat is a Wi-Fi-enabled thermostat that is meant to integrate with your typical ‘smart home’ setup, with mobile app control available as well. Of course, just using it as-is would be extremely boring, so fortunately we have [author0] to take it apart and reverse-engineer its encrypted firmware . Of the two brains in this thermostat the first is a succinctly named Renesas R7FA6M4AF3CFP MCU containing a 200 MHz Cortex-M33 core with TrustZone features to theoretically keep out any firmware hackers. Handling the wireless side is a Realtek RTL8721DM Wi-Fi/BLE 5.0 SoC. There are also two Winbond Flash chips connected to these two main chips, with their contents of course encrypted. Fortunately there are plenty of test points to connect to, for which a custom pogo-pin equipped breakout board was created. Cracking the encryption for the Realtek turned out to be as simple as using its RSIP decrypt-on-the-fly feature. From there exploring the firmware...