DIY Wind Tunnel Aims To Educate The Youth

October 1, 2022 by Lewin Day 20 Comments

Typically, when we talk about wind tunnels, we think of the big facilities in use by the aerospace and motorsports industries. However, there’s nothing stopping you building a wind tunnel of your very own, and it may even be easier than you think! [Jude Pullen] has whipped up just such a design with DIY in mind.

Intended for high school Design & Technology (D&T) classes, it uses relatively simple materials construction techniques. The airflow straightener is built out of PVC pipes, and the end boxes built out of cardboard. The transparent walls for observation are created out of acrylic, while a simple fan provides the necessary flow. The desk-sized wind tunnel can then be instrumented with a manometer, tachometer, and anemometer to measure pressure, fan speed, and wind speed. [Jude] also explores experiments that can be run in the wind tunnel, such as working with a small balsa wood glider and measuring the lift it generates with a scale.

[Jude] has a very pragmatic and real-world understanding of such projects, too. He notes the difference between making things to measure, and making them to fit, and highlights the values of both approaches. It’s a much more holistic approach than simply berating students to “do it right” or “do it better” when making things in a D&T class.

Use of a basic wind tunnel is often not taught to engineering students until at least the second or third year of an engineering degree, after all the boring math and static analysis has been dealt with. However, there’s no reason high school physics students can’t understand the physics involved, and they’re more than capable of undertaking such a build. Starting such education early often nets huge benefits for individuals and their eventual careers.

Once you’ve got yourself a wind tunnel, you might want to start thinking about some flow visualization, which gets really exciting.

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Lamp Flashing Module Is Perfect For Automotive Use

October 1, 2022 by Lewin Day 17 Comments

Modern cars tend to have quite advanced lighting systems, all integrated under the control of the car’s computer. Back in the day, though, things like brake lights and indicators were all done with analog electronics. If your classic car needs a good old-fashioned flasher module, you might find this build from [DIY Guy Chris] useful.

It’s an all-analog build, with no need for microcontrollers or other advanced modern contrivances. Instead, a little bipolar PNP transistor and a beefier NPN MOSFET as an oscillator, charging and discharging a capacitor to create the desired flashing behavior. Changing the size of the main capacitor changes the flash rate. The MOSFET is chosen as running 12 volt bulbs requires a decent amount of current. The design as drawn is intended to run up to eight typical automotive bulbs, such as you might find in indicator lamps. However, [Chris] demonstrates the circuit with just four.

Flasher circuits were in regular use well into the 1990s. The original Mazda Miata has a very similar circuit tucked up under the dashboard to run the turn signals. These circuits can be hard to find for old cars, so building your own may be a useful workaround if you’re finding parts hard to come by. Video after the break.

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Finding Digital Solace In An Old Nokia Phone

September 20, 2022 by Tom Nardi 9 Comments

We don’t have to tell you that the current mobile phone market is a bit bleak for folks who value things like privacy, security, and open source. While there have been a few notable attempts to change things up, from phone-optimized versions of popular Linux distributions to the promise of modular handsets — we still find ourselves left with largely identical slabs released by a handful of companies which often seem to treat the customer as a product.

Instead of waiting for technological relief that may never come, [vrhelmutt] has decided to take matters into their own hands by looking to the past. Specifically, by embracing the relatively uncommon Nokia Asha 210. Released in 2013, this so-called “feature phone” offers a full QWERTY keyboard, Nokia’s Series 40 operating system, WiFi, Bluetooth, and a removable BL-4U battery. Unfortunately, with 2G cellular networks quickly being shut down, it’s not likely to get a signal for much longer (if at all, depending on where you live).

So why would you want to use some weird old Nokia phone in 2022? [vrhelmutt] argues that there’s a whole world of S40 software out there that can still be put to use, ranging from games to SSH clients. It’s also relatively easy to develop your own S40 applications in Java, with the original software development kit still freely available online. Combined with the solid (if considerably dated) hardware, this makes the Nokia Asha 210 a surprisingly compelling choice for a pocket hacking platform.

Whether you’re looking for a cheap device that will let you chat on IRC from your couch, or want to write your own custom software for controlling your home automation or robotics projects, you might want to check the second-hand market for a Nokia Asha 210. Or if you’re eager to get experimenting immediately, [vrhelmutt] is actually selling these phones pre-loaded with a wide array of games and programs. Don’t consider this to be an official endorsement; frankly we’re not feeling too confident about the legality of redistributing all this software, but at least it’s an option for those looking to get off the modern smartphone thrill-ride.

If you’re looking for something even farther removed from today’s mobile supercomputers, perhaps we could interest you in the Rotary Un-Smartphone.

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Walkmp3rson Is An MP3 Player Like Sony Never Made

September 20, 2022 by Kristina Panos 29 Comments

If you weren’t already well aware, the 90s are like, so hot right now, and that includes cassette tapes for some reason. (Even though we personally didn’t have a CD player until 1998, they were around as early as 1982.) But if you don’t dig the quality of cassettes, or if you’d just rather carry around more than 45-120 minutes worth of music, than [John Edgar Park]’s Walkmp3rson is definitely the build for you. That’s pronounced ‘Walkperson’, as in a 21st century MP3-based update of the classic Walkman.

Inside this amazing 3D printed enclosure, you’ll find an Adafruit Feather RP2040 controlling the screen, handling input from the rotary encoder and those sweet mechanical keyswitches, and of course, playing audio files from SD cards through the amplifier breakout board. And no, this isn’t just another MP3 player — well, it kind of is, but the presentation really goes a long way here.

There are tons of retro-modern nods, like the cassette reel animation that plays on the TFT screen, the boxy enclosure, and the fact it involves physical media. Oh yes — you get to insert an SD card whenever you want to change albums/discographies/genres/whatever. In fact, this would be a great use of older, smaller SD cards. You could go all out and make tiny album art to slip inside those milky plastic cases. Check out the brief demo video after the break.

Looking to play your tunes on a microcontroller, but not a fan of the Walkman aesthetic? In June we covered a similar audio player powered by the ESP32 that does an uncanny impersonation of a portable tape deck that you might be interested in.

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Making A Tape Echo The Traditional Way

September 14, 2022 by Dave Walker 12 Comments

[Juan Nicola] has taken inspiration from the musician hackers of old and re-purposed a reel-to-reel tape recorder into a tape-echo for his guitar with a built-in valve amplifier (video in Spanish).

The principle is to record the sound of the guitar onto a piece of moving magnetic tape, then to read it back again a short time later. This signal is mixed with the live input and re-recorded back onto the tape further back. The effect is heard as an echo, and this approach was very popular before digital effects became readily available.

[Juan] installed a new read-head onto his Grundig TK40 and managed to find a suitable mechanical arrangement to keep it all in place. He has since updated the project by moving to a tape loop, allowing an infinite play-time by re-using the same piece of tape over and over.

Turning tape machines into echo effects is not a new idea, and we’ve shown a few of them over the years, but every one is slightly different!

Both versions are shown after the break. YouTube closed-caption auto-translate might come in handy here for non-Spanish speakers.

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Neon Lamps — Not Just For Pilot Lights

September 13, 2022 by Dan Maloney 30 Comments

It’s easy to see why LEDs largely won out over neon bulbs for pilot light applications. But for all the practical utility of LEDs, they’re found largely lacking in at least one regard over their older indicator cousins: charm. Where LEDs are cold and flat, the gentle orange glow of a neon lamp brings a lot to the aesthetics party, especially in retro builds.

But looks aren’t the only thing these tiny glow lamps have going for them, and [David Lovett] shows off some of the surprising alternate uses for neon lamps in his new video. He starts with an exploration of the venerable NE-2 bulb, which has been around forever, detailing some of its interesting electrical properties, like the difference between the voltage needed to start the neon discharge and the voltage needed to maintain it. He also shows off some cool neon lamp tricks, like using them for all sorts of multi-vibrator circuits without anything but a few resistors and capacitors added in. The real fun begins when he breaks out the MTX90 tube, which is essentially a cold cathode thyratron. The addition of a simple control grid makes for some interesting circuits, like single-tube multi-vibrators.

The upshot of all these experiments is pretty clear to anyone who’s been following [David]’s channel, which is chock full of non-conventional uses for vacuum tubes. His efforts to build a “hollow state” computer would be greatly aided by neon lamp circuits such as these — not to mention how cool they’d make everything look.

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This Vintage Alphanumeric Display Was Huge, Hot, Heavy, And Expensive

September 4, 2022 by Donald Papp 20 Comments

It’s easy to take display technology for granted nowadays, but the ability to display data in a human-readable way was not always easy. This is demonstrated well by the Pinlite 30003 Alphanumeric Display Module, a four-character display that was pure luxury for its time.

Each display is a rectangular vacuum tube containing 17 incandescent light filaments.

Not only were the 17 segments that make up each display capable of showing any letter or number, but they were even daylight-readable! Each of those 17 segments is an incandescent lamp filament, which is how the required brightness was achieved. The sturdy module shown here holds four such displays, each of which is on its own pluggable board with a dedicated character decoder chip directly behind it.

As [AnubisTTL] points out, the resulting unit is bulky, has terrible character spacing, and was no doubt very costly. By today’s standards, it is almost unimaginably heavy, hot, and impractical. But before high-brightness LEDs were a thing, a daylight-readable alphanumeric character display was really something special. It would absolutely have been worth the money and effort to the right people.

Before small and efficient displays were commonplace, the solution to the problem of how to display data efficiently and in an easy-to-read format took a lot of really unusual (and clever) turns as engineers worked around the limitations of the time. This resulted in oddities like the SD-11 Sphericular Display, which is mostly empty space on the inside. Another great example is the Eidophor, a projector from before projectors were even a thing.