Parachute Drops Are Still A Viable Solution For Data Recovery From High Altitude Missions

Once upon a time, when the earliest spy satellites were developed, there wasn’t an easy way to send high-quality image data over the air. The satellites would capture images on film and dump out cartridges back to earth with parachutes that would be recovered by military planes.

It all sounds so archaic, so Rube Goldberg, so 1957. And yet, it’s still a viable method for recovering big globs of data from high altitude missions today. Really, you ask? Oh, yes indeed—why, NASA’s gotten back into the habit just recently!

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A 360° View Of A Classic Drive-In Speaker

Readers of a certain vintage no doubt have pleasant memories of drive-in theaters, and we are chuffed to see that a few hundred of these cinematic institutions endure today. While most theaters broadcast the audio on an FM station these days, the choice is still yours to use the chunky, often crackly speaker that attaches to the car window.

Seeking to relive the drive-in audio experience at home, [codemakesitgo] picked up a drive-in theater speaker on eBay and turned it into a Bluetooth device that sounds much better than it did in its weather-beaten days outside.

There isn’t a whole lot to this build — it’s essentially a new speaker cone, a Bluetooth receiver, an amp, and a battery. The real story is in the way that [codemakesitgo] uses Fusion360 to bring it all together.

After 3D scanning the case, [codemakesitgo] made sure each piece would fit, using a custom-built model of the new speaker and a 3D model of a custom PCB. Good thing, too, because there is barely enough clearance for the speaker. Be sure to check out the brief demo video after the break.

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Ask Hackaday: What Do You Do When You Can’t Solder?

Ah, soldering. It’s great for sticking surface mount parts to a PCB, and it’s really great for holding component legs in a plated through-hole. It also does a pretty great job of holding two spliced wires together.

With that said, it can be a bit of a fussy process. There are all manner of YouTube videos and image tutorials on the “properest” way to achieve this job. Maybe it’s the classic Lineman’s Splice, maybe it’s some NASA-approved method, or maybe it’s one of those ridiculous ones where you braid all the copper strands together, solder it all up, and then realize you’ve forgotten to put the heat shrink on first.

Sure, soldering’s all well and good. But what about some of the other ways to join a pair of wires?

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The Hot Chocolate Effect Explained

This is the time of year when people in the Northern Hemisphere like to enjoy hot beverages like hot chocolate. [The Action Lab] uses hot chocolate to demonstrate an odd acoustic effect. Tapping a container of hot chocolate — or even just hot water — will make a sound at a certain frequency. But if you keep tapping, the frequency of the sound will gradually increase. Don’t know why? Don’t worry, neither did scientists until around 1980.

The secret is bubbles and the speed of sound through air vs a liquid. The speed of sound in the liquid and the height of the liquid in the cup set the frequency. However, the speed of sound changes based on the bubbles, which alters the frequency.

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Arduino Auto-Glockenspiel Looks Proper In Copper

What is it about solenoids that makes people want to make music with them? Whatever it is, we hope that solenoids never stop inspiring people to make instruments like [CamsLab]’s copper pipe auto-glockenspiel.

At first, [CamsLab] thought of striking glasses of water, but didn’t like the temporary vibe of a setup like that. They also considered striking piano keys, but thought better of it when considering the extra clicking sound that the solenoids would make, plus it seemed needlessly complicated to execute. So [CamsLab] settled on copper pipes.

That in itself was a challenge as [CamsLab] had to figure out just the right lengths to cut each pipe in order to produce the desired pitch. Fortunately, they started with a modest 15-pipe glockenspiel as a proof of concept. However, the most challenging aspect of this project was figuring out how to mount the pipes so that they are close enough to the solenoids but not too close, and weren’t going to move over time. [CamsLab] settled on fishing line to suspend them with a 3D-printed frame mounted on extruded aluminium. The end result looks and sounds great, as you can hear in the video after the break.

Of course, there’s more than one way to auto-glockenspiel. You could always use servos.

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Roll Your Own SDR

If you have software-defined radio hardware and you are only using someone elses’ software, you are missing out on half of the fun. [Tech Minds] shows you how easy it can be to roll your own software using GNU Radio Companion in a recent video.

GNU Radio usually uses Python, but with the companion software you rarely need to know any actual Python. Instead, you simply drag blocks around to represent filters, DSP processing, and other functions you need to create the processing for your application.

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Hackaday Podcast Episode 248: Cthulhu Clock Radio Transharmonium, Thunderscan, And How To Fill Up In Space

This week, Elliot sat down with Dan for the penultimate podcast of 2023, and what a week it was. We started with news about Voyager; at T+46 years from launch, any news tends to be bad, and the latest glitch has everyone worried. We also took a look at how close the OSIRIS-REx mission came to ending in disaster, all for want of consistent labels.

Elliot was charmed by a Cthulhu-like musical instrument, while Dan took a shine to a spark gap transmitter that’s probably on the FCC’s naughty list. Any sufficiently advanced technology is indistinguishably from magic, and we looked at the laser made possible by the magician-in-chief himself, C.V. Raman. Why would you stuff a PSU full of iron filings? Probably for the same reason you’d print fake markings on a 6502 chip. We also took a look at the chemistry and history of superglue, a paper tape reader that could lop off your arm, and rocket gas stations in space.

 

Grab a copy for yourself if you want to listen offline.

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