Open Source Ultrasonic Anemometer

July 6, 2021 by 12 Comments

Weather stations are a popular project for experimenting with various environmental sensors, and for wind speed and direction the choice is usually a simple cup anemometer and wind vane. For [Jianjia Ma]’s QingStation, he decided to build another type of wind sensor: An ultrasonic anemometer.

Ultrasonic anemometers have no moving parts but come at the cost of significantly more electronic complexity. They work by measuring the time it takes for an ultrasonic audio pulse to be reflected the receiver across a known distance. Wind direction can be calculated by taking velocity readings from two ultrasonic sensor pairs perpendicular to each other and using a bit of simple trigonometry. For an ultrasonic anemometer to work properly, it requires a carefully designed analog amplifier on the receive side and a lot of signal processing to extract the correct signal from all the noise caused by secondary echoes, multi-pathing, and the environment. The design and experimentation process is well-documented. Since [Jianjia] does not have access to a wind tunnel for testing and calibration, he improvised by mounting the anemometer on his car’s roof and going for a drive. This yielded readings that were proportional to the car’s GPS speed, but a bit higher. This might due to a calculation error, or external factors like wind, or disturbed airflow from the test car or other traffic.

Other sensors include an optical rain sensor, light sensor, lighting sensor, and a BME280 for air pressure, humidity, and temperature. [Jianjia] plans to use the QingStation on an autonomous boat, so he also included an IMU, compass, GPS, and a microphone for environmental sounds. The fact that none of the sensors have moving parts is a major advantage for this use case, and we look forward to seeing the boat project. All the hardware and software are open-source and available on GitHub.

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Bellow-Cooled PC Is A Well Engineered Display Piece

July 6, 2021 by 19 Comments

The cooling systems on high-performance PCs are often a large part of their visual appeal, but we’ve never seen anything like [DIY Perks]’ latest build: A massive bellow-cooled PC.

The system is derived from a silent bellow system built by [DIY Perks] in 2020. It uses a clever combination of hydraulics and neodymium magnets to smoothly reciprocate a large plate within a chamber. Instead of blowing the air straight into the room, it pushes it through a pair of wood ducts into a second chamber with PC components, and out through a water-cooling radiator. To prevent the hot air from being sucked back in as the bellow reciprocates, a row of check valves was added on each side of the PC chamber and at the external intakes. The sides of the bellow chamber and PC chamber are made of glass to allow a full view of the internal components.

The build was not without complications. While disassembling the old bellow, the acrylic tube in which the magnet reciprocates shattered. When a replacement rube arrived, [DIY Perks] discovered the magnet’s fit was very loose. He solved this by increasing the thickness of the magnet’s nickel coating with another run of electroplating. To achieve a uniform coating, he agitated the plating solution by suspending the magnet from a small speaker playing a sine-wave tone. The cooling performance is excellent, keeping the CPU and GPU at 60C or below, even while running them at full tilt.

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How To Drive Smartphone Screens Over HDMI

July 5, 2021 by 22 Comments

Compared to most small LCDs sold to makers, smartphone screens boast excellent color, brightness, and insanely high resolution. Unfortunately, driving them is rarely straightforward. In an attempt to make it easier, [peng-zhihui] set about developing tools to allow such screens to be driven from a simple HDMI feed. For those whose Chinese is a little rusty, the Google Translate link might prove useful.

The first attempt was using Toshiba’s TC358870XBG ASIC, capable of driving screens over MIPI DSI 1.1 from an HDMI input. [peng-zhihui] designed a simple test module for the chip based on the company’s evaluation board design, with [ylj2000] providing software to help get that solution off the ground.

However, for now that solution is imperfect, so [peng-zhihui] also experimented with the Longxun LT6911 HDMI to MIPI driver. While cheap, information on the part is scarce, and the company’s own source code for using the hardware is only accessible by signing an NDA. However, [peng-zhihui] made pre-compiled firmware available for those that wish to work with the hardware.

[peng-zhihui] has put these learnings to good use, building a power bank with a MIPI screen using what appears to be the Longxun chip. The device can supply power over USB and also act as an HDMI display.

While it’s early days yet, and driving these screens remain difficult, it’s great to see hackers getting out there and finding a way to make new parts work for them. We’ve seen similar work before, using an FPGA rather than an off-the-shelf ASIC. If you’ve found your own way to get these high-end displays working, be sure to drop us a line!

[Thanks to peterburk for the tip!]

You Can Put Toothpaste In The Tube (With Effort)

July 5, 2021 by 20 Comments

Old wives’ tales, folk knowledge, common sayings, and even cliches and idioms are often taken as givens since they form an often unnoticed part of our vocabulary and culture. There’s so many examples that it’s possible to fill a 17-season TV show busting potential myths like these, and even then there are some that slipped by. For example, the saying “you can’t put toothpaste back in the tube” which, as it turns out, is not as impossible as we might be led to believe.

This video is the product of [Tyler Bell] who has taken this idiom on as a challenge. To figure out if it was possible he first got to work building a vacuum chamber, which turned out to be a little easier than he thought it would be. After cutting a piece of polycarbonate tube and sanding it down, all that was needed were some rubber gaskets and fittings for the vacuum pump.

From there, the theory was to put an empty toothpaste tube into the vacuum chamber, pump all of the air out, and let atmospheric pressure “push” the toothpaste back into the tube. During [Tyler]’s first run he thought that it had worked successfully but it turned out that he had just inflated the empty toothpaste tube like a balloon. Further iterations were able to return some of the toothpaste to the tube, but each time some air would eventually work its way into the toothpaste which would immediately fill the remaining space in the tube with air rather than toothpaste.

While not completely successful, he was able to get some toothpaste back into the tube with a relatively small bill of materials. It’s not likely that this experiment will result in a change of this particular idiomatic expression, but it was interesting to put it to the test nonetheless. For other instances of toothpaste and its relationship to tubes, both inside and out, be sure to check out this recent piece on various methods of toothpaste storage.

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Wooden Linear Clock Aided By GPS

July 5, 2021 by 23 Comments

The notion of segmenting and quantizing the day into discrete segments of time is perhaps one of the most human things we do. Heralding back to a simpler era when a day was just a progression of sunrise to sunset, [James Wilson] created a beautiful linear clock that shows time as progress throughout the day.

For previous projects, [James] had used nixie tubes but the headache of the inverters, high voltages, and tight spaces led him to instead use mini-LED’s. Two PCBs were manufactured, one as the display and one to hold the GNSS module as it works best when mounted horizontally to point at the sky. Two rows of 112 tightly packed LEDs make a great stand-in for bar graph style tubes and are are controlled by TLC5926 shift registers. The venerable STM32G0 was chosen as the microcontroller to power the clock. With the help of some approximating functions and the location provided by the GNSS module [James] had the position of the sun which he then could turn into a % of progress through the sky.

The enclosure was modeled after the mid-century modern look and made of several pieces of wood CNC’d and then glued together. Machining it out of a solid piece of wood would have been difficult as finding long enough end mills that could carve out the interior is tricky. We think the resulting clock looks wonderful and the walnut accents the maple nicely.

The writeup is highly detailed and we love the honest explanations of what choices were made and why. The code is available on GitHub. Or if perhaps you’d rather eschew the LED’s and go for something more physical there’s always this ratcheting linear clock to draw inspiration from.

DIY Air Quality Sensor

July 5, 2021 by 6 Comments

 

[Andrew Lamchenko], who has built a number of small e-ink-based sensors this year, released another design called the eON Indoor Air Quality Sensor. As his previous sensor designs, the eON boasts a striking appearance with all the spit and polish of a commercially made product. Except [Andrew]’s design is completely open-source.

Besides showing air quality, it also shows basic weather conditions, and there’s a built-in weather forecasting algorithm as well. It can operate standalone or use the radio module to send readings to a smart home system.

The core sensor is the SGP40, which detects volatile organic compounds (VOCs) in the air while consuming less than 3 mA (compared to the 48 mA of the previous generation). There’s a temperature, barometric pressure, humidity, and light sensors in the package as well. Like many projects these days, [Andrew] encountered parts supply issues along the way. Because of that, and to make the design more flexible, several versions of the board have been made to accommodate the different permutations of:

  • Displays
    • 2.13-inch e-ink display
    • DES e-ink display, coming soon
  • Radio, four flavors
    • MINEW MS88SF3 (nRF52833, nRF52840)
    • MINEW MS50SFA1 (nRF52810, nRF52811)
    • MINEW MS50SFA2 (nRF52832)
    • EBYTE E73-2G4M08S1C (nRF52833, nRF52840)
  • Temp / Pressure sensor:
    • BME280
    • BMP280
    • SHTC3

[Andrew] not only designed the sensor but has done a thorough job on the documentation. Check out the GitHub repository of the project for a complete data package covering all aspects of the design, including the weather forecasting app note by John Young (an NXP engineer, not the astronaut). Last week the design was named as a finalist of the 2021 Hackaday Prize. We’re excited to see where he goes with this between now and the end of October!

Do you use an air quality sensor in your home? If so, is it only for informational purposes or do you take action based on the data, such as automatically turning on a fan or escaping to the countryside? Let us know in the comments below.

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How To Make A Collapsible Container Without Breaking Down

July 5, 2021 by 5 Comments

How hard could it be to make a collapsible silicone container? Turns out, it’s really, really hard — collapsible containers have rigid guidelines. Just ask [Eric Strebel], who failed dozens of times before finally getting it right (video, embedded below).

[Eric] started with an SLA-printed two-part mold and a silicone formulation with a Shore durometer of A 40 — this is the measure of hardness for silicone, polymers, and elastomers in the sense that the piece will resist indentation. The first twenty-four attempts all came out looking great, but not a single one of them would collapse and stay collapsed.

Eventually, [Eric] went back to the drawing board and played with the angles of the flex points, the thickness of the living hinges, and the wall thicknesses, which have to be strong enough to stay collapsed.

For attempt #25, [Eric] took the part out of the mold about three hours in and tried curing it in the collapsed state. Persistence paid off, and the part finally collapses and stays that way. Get yourself some popcorn and check out the fail-fest after the break. You know what we always say — fail fast, fail often.

[Eric] has made many molds both from silicone and for silicone. Some of them are really big!

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