Gemini* and Gopher

• Science

  • Voltage Divider on Slide Rule

    As such, this is well-suited for our slide rule, except we have to reckon with the addition in the denominator.

    I had a case of this last week, where I was wanting a voltage divider for biasing, with 15 V input and 696 mV output. I wanted the resistor values to be as high as practical. So I aligned the top C scale value 6.96 with the bottom D scale value 1.5, setting the ratio. I could tell — using a little rounding — that the denominator should be somewhere between 15 and 30 times the numerator. I can start with the small resistor — the numerator — and get an idea of what the denominator resistance would need to be.

    At the moment, my horizontal ruler shows C scale values between about 5 and 10 and D scale values between about 1 and 2, which — on the lower end of that — could be interpreted for our purposes as 500 kΩ and 10 MΩ. But 10 MΩ is not ideal, as the biggest resistors I have left are 5.6 MΩ.

  • Mechanics, Ideas, Organization, Style

    These four terms can be used to grade essays, as opposed to those English (or sub in a less bad language as appropriate of which there are many but declining in number) teachers who grade more on the feelies. C? B? No idea why. The terms could also be used to rate different books, though published books tend to be not bad on at least the mechanics, unless the editor did a terrible job or these days slop slop slop slop slop slop slop lovely slop!

• Technology and Free Software

  • Image Quality Labs Gives the Arduino UNO Q Eyes, Adds Raspberry Pi Camera Module Compatibility

    Image Quality Labs is aiming to make it easier to use common camera modules, including the popular Raspberry Pi Camera Module family, with the Arduino UNO Q single-board computer — by adapting its board-to-board connectors into MIPI Camera Serial Interface (CSI) ports.

    "IQL Camera Bridge for Arduino UNO Q makes it easy to add real camera functionality to Arduino's newest high-performance platform," IQL's Jason Cope says of the company's design. "It provides a clean, supported hardware interface that connects thousands of readily available camera modules to the UNO Q, without requiring custom camera hardware. Whether you're prototyping computer vision, teaching embedded imaging, or evaluating cameras for a future product, the IQL Camera Bridge offers a practical, well-engineered starting point."

  • Researchers Turn to 3D Printing for a Low-Cost, Body-Powered Curling Prosthetic Finger

    Researchers from the University of Arizona, Sampoerna University, and Politeknik Negeri Jakarta have developed a 3D-printable finger prosthesis powered by the wearer — with the aim of restoring natural grip functionality.

    "High cost and ongoing maintenance requirements keep many finger amputees in underdeveloped nations from accessing prosthetic devices. The most prevalent upper-limb amputation, trans-phalangeal amputation (accounting for about 78% of cases), is addressed in this paper as requiring a low-cost, effective finger prosthesis. Using a single degree-of-freedom (1-DOF) connection mechanism and additive manufacturing, a body-powered prosthetic finger was designed and built," the researchers explain of the project. "Aiming to restore fundamental grip function, the device is customizable to the user's hand size."

  • The Raspberry Pi-Powered Sensea Delivers Color Imagery and Temperature Readings From Under the Waves

    Pseudonymous educator and maker "Unboxed_STEM," hereafter simply "Unboxed," has shared a design for a low-cost Raspberry Pi-powered underwater gadget designed for sub-surface videography and temperature monitoring: Sensea.

    "We talk a lot about protecting oceans and rivers — but how do we actually measure what's going on below the surface," Unboxed rhetoricizes by way of introduction to the project. "Sensea is a DIY underwater explorer built with a Raspberry Pi, camera, and simple modular sensors that brings citizen science within reach of any STEM [Science, Technology, Engineering, and Math] club or classroom. It captures underwater video and logs time-stamped water temperature data — even in remote locations without internet access."

  • Theo Heng's PD240W Is a Raspberry Pi RP2040-Powered USB Power Delivery Supply for Motors

    Robotics student Theo Heng has designed a compact adjustable power supply for motors that uses a Raspberry Pi RP2040 microcontroller to negotiate up to 48V and 5A from a suitable USB Power Delivery (USB PD) 3.1 power source: the PD240W.

    "PD240W [is] an adjustable power supply for motor drives using USB [Type]-C Power Delivery negotiation, supporting up to 240W at 48V 5A," Heng explains of the compact device. "This device is designed to be compatible with USB-PD 3.1 and above. Firmware runs on a Raspberry Pi Pico (RP2040). [It] negotiates Fixed, PPS [Programmable Power Supply] (5–21V programmable), and AVS [Adjustable Voltage Supply] (15–48V EPR [Extended Power Range]) profiles."

  • This Upcycled "Ephemeral Printer" Creates Temporary Advice — or Insults — with Laser Light

    Pseudonymous maker "slartibartfist" has built a printer with self-destructing printouts — by shining a laser onto glow-in-the-dark paper.

    "Got a 3D printer recently," slartibartfist explains of the project, so I thought I'd revisit an old idea: 'printing' letters with light onto glow in the dark paper. [It has] two modes: Oblique Strategies (displays a random creative idea to help you work through creative roadblocks), and Insult mode (random insult, because I have a kid and it'll make him smile)."

    Traditionally, a printer is the go-to tool when you're looking for a permanent hard-copy of something — but the printer slartibartfist has built is by its very nature ephemeral. Built using primarily salvaged components, the printer uses stepper motors to run a low-power laser pointer along a sheet of glow-in-the-dark paper, charging it up such that where the laser was shining is phosphorescent when the lights go out.

  • Internet/Gemini

    • Guy Dupont Makes an "IRL YouTube" with Home Assisant Automation and a QR Code Scanner

      Maker Guy Dupont was looking for a way to allow his three-year-old daughter access to a controlled and curated subset of videos on YouTube without providing unfettered access to even YouTube kids — and with a strict time limit. The solution: a physical binder of video URLs.

      "There's a ton of high-quality, free (we're the product, blah, blah), educational content on YouTube. If she's gonna be in front of a screen, we'd prefer that some of that time is spent learning," Dupont explains of the curation aspect. "There's a ton of [terrible] content on YouTube that's designed only to grab and hold her attention. If she's gonna be in front of a screen, we'd prefer that none of that time is spent watching this. We've observed that when she knows that there's a bunch of other stuff to watch, she wants to switch what she's watching more frequently. We're trying to cultivate an attention span over here! Seeing 30 new thumbnails on the way to the video we agreed on inevitably leads to 'wait, what was that one, I want to watch that now!'"