LED Spectrum Visualizer Driven By Raspberry Pi

February 22, 2021 by Lewin Day 19 Comments

Back in the 1980s, spectrum displays on audio equipment were absolutely must have, and the aesthetic came to define the era. This lingered on through the 1990s, and remains a cool look even to this day. [Arduino Guy] decided to put together such a display using a Raspberry Pi and a large LED display.

The LED display in question is of the 64×64 RGB type, available from Aliexpress and other electronics suppliers online. To run the display, an Adafruit RGB Matrix Hat is used with the Raspberry Pi 3B, which makes driving the panel a cinch. The visual effect is run via a Python script, which plays a wave file and produces the spectrum graphics via a Fast Fourier Transform.

While the code isn’t able to act as a general-purpose equalizer display for any content played on the Raspberry Pi, creating such a script could be an entertaining exercise for the reader. Alternatively, the Pi could be hooked up to a microphone to run the display based on ambient room noise. In any case, we’ve seen great projects like this before, such as this laser-based display. Video after the break.

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3D Print A PCB The Hard Way

February 22, 2021 by Al Williams 15 Comments

There’s an old joke about the physics student tasked with finding the height of a building using a barometer. She dropped the barometer from the roof and timed how long it took to hit the ground. Maybe that was a similar inspiration to [Moe_fpv_team’s] response to the challenge: use a 3D printer to create a PC board. The answer in that case? Print a CNC mill.

[Moe] had some leftover 3D printer parts. A $40 ER11 spindle gets control from the 3D printer software as a fan. The X, Y, and Z axis is pretty standard. The machine can’t mill metal, but it does handy on plywood and fiber board and should be sufficient to mill out a PCB from some copper clad board.

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How To Design A Custom Generator Interlock Plate

February 22, 2021 by Tom Nardi 85 Comments

If you connect a generator to your home’s main electrical panel when the power goes out, you need to make sure the main breaker is shut off. Otherwise, when the power comes back on, you (or the linemen) are going to have a bad time. There are commercial interlock plates which physically prevent the generator and main breakers from being switched on at the same time, but since they tend to be expensive, [HowToLou] decided to make one himself.

The hardest part of this project is designing the template. It needs to be carefully shaped so its resting position prevents the generator’s breaker from being switched on under normal circumstances, but once the main is turned off and out of the way, you should be able to lift it up and have the clearance to flip the lower breaker. Spending some quality time at the breaker box with tape and a few pieces of cardboard is going to be the easiest way of finding the proper shape.

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Stunning Footage Of Perseverance Landing On Mars

February 22, 2021 by Dan Maloney 70 Comments

The much-anticipated video from the entry descent and landing (EDL) camera suite on the Perseverance rover has been downlinked to Earth, and it does not disappoint. Watch the video below and be amazed.

The video was played at the NASA press conference today, which is still ongoing as we write this. The brief video below has all the highlights, but the good stuff from an engineering perspective is in the full press conference. The level of detail captured by these cameras, and the bounty of engineering information revealed by these spectacular images, stands in somewhat stark contrast to the fact that they were included on the mission mainly as an afterthought. NASA isn’t often in the habit of adding “nice to have” features to a mission, what with the incredible cost-per-kilogram of delivering a package to Mars. But thankfully they did, using mainly off-the-shelf cameras.

The camera suite covered nearly everything that happened during the “Seven Minutes of Terror” EDL phase of the mission. An up-looking camera saw the sudden and violent deployment of the supersonic parachute — we’re told there’s an Easter egg encoded into the red-and-white gores of the parachute — while a down-looking camera on the rover watched the heat shield separate and fall away. Other cameras on the rover and the descent stage captured the skycrane maneuver in stunning detail, both looking up from the rover and down from the descent stage. We were surprised by the amount of dust kicked up by the descent engines, which fully obscured the images just at the moment of “tango delta” — touchdown of the rover on the surface. Our only complaint is not seeing the descent stage’s “controlled disassembly” 700 meters away from the landing, but one can’t have everything.

Honestly, these are images we could pore over for days. The level of detail is breathtaking, and the degree to which they make Mars a real place instead of an abstract concept can’t be overstated. Hats off to the EDL Imaging team for making all this possible.

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PVC Pipes Play “Popcorn” Perfectly

February 22, 2021 by Kristina Panos 16 Comments

There are all sorts of fun ways to make music with empty jugs and other things that resonate with a popping sound when poked with a finger. Should you ever get stuck on that proverbial desert island, you can entertain yourself by making cheerful, staccato music with nothing but a fingertip and the inside of your cheek. At the very least, it will keep your spirits up until you can fashion an ocarina from a coconut.

[Nicolas Bras] loves to make homemade instruments. When he saw all the scrap pieces of perfectly finger-sized PVC tubing piling up around the workshop, he decided to make an instrument specifically to play the effervescent synth tune “Popcorn”. (Video, embedded below.) He plays it by plugging and quickly unplugging wood-capped pipes with his fingers, and using another PVC tube to blow across the tops of them to fill out the orchestration.

[Nicolas] started by making a two-octave chromatic scale with 25 pipes ranging from C4 to C6. He kept building on it from there in both directions, ultimately ending up with a poppin’ 68-note pipe organ that sounds fantastic. If you’re interested in getting the sound samples, [Nicolas] has those and the instrument plans available through Patreon.

Be sure to check out the build and demo video below — it’s a joy to see it come together, and the whole thing clocks in under six minutes. Take our word for it and don’t jump to the “Popcorn” cover, because the build-up is necessary for maximum enjoyment.

Hungry for more “Popcorn”? Here’s a robotic glockenspiel busting out a striking cover.

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Flapping Wings And The Science Of How Bees Can Fly

February 22, 2021 by Lewin Day 70 Comments

Jerry Seinfeld launched his career with Bee Movie, an insect-themed animated feature that took the world by storm in 2007. It posed the quandary – that supposedly, according to all known laws of aviation, bees should not be able to fly. Despite this, the bee flies anyway, because bees don’t care what humans think is impossible.

The quote isn’t easily attributed to anyone in particular, but is a cautionary tale about making the wrong assumptions in an engineering context. Yes, if you model a bee using the same maths as an airliner, of course you’ll find that it shouldn’t be able to fly. Its tiny wings can’t possibly generate enough lift to get its body off the ground. But that’s because the assumption is an erroneous one – because bees don’t fly in the same way planes do. Bees flap their wings. But that’s just the beginning. The truth is altogether more complex and interesting! Continue reading “Flapping Wings And The Science Of How Bees Can Fly” →

DIY Neuroscience Hack Chat

February 22, 2021 by Dan Maloney 8 Comments

Join us on Wednesday, February 24 at noon Pacific for the DIY Neuroscience Hack Chat with Timothy Marzullo!

Watch a film about a mad scientist from the golden age of Hollywood and chances are good that among the other set pieces, you’ll see human brains floating in jars of cloudy fluid wired up to electrodes and fancy machines. It’s all made up, of course, but tropes work because they’re based on a kernel of truth, and we in the audience know that our brains and the other parts of our nervous system do indeed work on electricity. Or more precisely, excitable tissues in our nervous systems pass electrochemical signals between themselves as waves of potential across cell membranes.

Studying this electrical world locked away inside our heads is a challenging, but by no means impossible, pursuit. Usable signals can be picked up, amplified, digitized, and recorded to help us understand what’s going on when we think, feel, move, sleep, wake, or just be. Neuroscience has made tremendous strides looking at these signals, but the equipment to do so has largely remained the province of large universities and teaching hospitals with ample budgets, leaving the amateur neuroscientist out of luck.

Tim Marzullo, co-founder of Backyard Brains, is looking to change all that. While working on his Ph.D. in neuroscience at the University of Michigan, he and Greg Gage looked for ways to make the tools of neuroscience research affordable to everyone. The result is the Neuron SpikerBox, a low-cost bioamplifier that can tap into the “spikes” of action potential in live neurons. Open-source tools like these have helped educators bring neuroscience experiments to STEM students, and even helped other scientists set up novel, low-cost experiments.

Tim will join us on the Hack Chat to talk about doing DIY neuroscience and designing the instruments that make it possible. Bring your “mad scientist” questions as we push back the veil of ignorance on how our brains work, one neuron at a time.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, February 24 at 12:00 PM Pacific time (UTC-8). If time zones have you tied up, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

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