African man hunched over a small robot car chassis

The Dar Es Salaam Hacker Scene And Gamut Detection

October 27, 2023 by Anne Ogborn 8 Comments

We’re on a sort of vacation in Tanzania at the moment and staying in a modest hotel away from the tourist and government district. It’s a district of small shops selling the same things and guys repairing washing machines out on the sidewalk. The guys repairing washing machines are more than happy to talk. Everybody’s amazingly friendly here, the hotel guy grilled us for an hour about our home state. But I really didn’t expect to end up in a conversation about computer vision.

In search of some yogurt and maybe something cooler to wear, we went on a little walk away from the hotel. With incredible luck we found a robotics shop a few blocks away. Mecktonix is a shop about two meters each way, stuffed full of Arduinos, robots, electronics components, servos, and random computer gear, overseen by [Yohanna “Joe” Harembo]. Nearby is another space with a laser engraver and 3D printer. The tiny space doesn’t stop them from being busy. A constant stream of automotive tech students from the nearby National Institute of Transport shuffle in for advice and parts for class assigned projects.

In between students, Joe demos an autonomous car he’s working on. In classic hacker fashion, he first has to reattach the motor driver board and various sensors, but then he demos the car and its problem – the video frame rate is very slow. We dive in with him and try to get some profiling using time.monotonic_ns(). He’s never done profiling before, so this is a big eye opener. He’s only processing one video frame every 4.3 seconds, using YOLO on a Pi 3, and yup, that’s the problem. I suggest he change to gamut detection or a Pi 4. Continue reading “The Dar Es Salaam Hacker Scene And Gamut Detection” →

Hackaday Podcast 242: Mechanical Math, KaboomBox, And Racing The Beam

October 27, 2023 by Kristina Panos 1 Comment

This week, Editor-in-Chief Elliot Williams and Kristina Panos met up from their separate but equally pin drop-quiet offices to discuss the best hacks of the previous week. Well, we liked these one, anyway.

First up in the news, it’s finally time for Supercon! So we’ll see you there? If not, be sure to check out the talks as we live-stream them on our YouTube channel!

Don’t forget — this is your last weekend to enter the 2023 Halloween Hackfest contest, which runs until 9 AM PDT on October 31st. Arduino are joining the fun this year and are offering some spooky treats in addition to the $150 DigiKey gift cards for the top three entrants.

It’s time for a new What’s That Sound, and Kristina was able to stump Elliot with this one. She’ll have to think of some more weirdo sounds, it seems.

Then it’s on to the hacks, beginning with an insanely complex mechanical central air data computer super-teardown from [Ken Shirriff]. We also learned that you can 3D-print springs and things by using a rod as your bed, and we learned whole lot about rolling your own electrolytic capacitors from someone who got to visit a factory.

From there we take a look at a Commodore Datassette drive that sings barbershop, customizing printf, and a really cool dress made of Polymer-dispersed Liquid Crystal (PDLC) panels. Finally we talk about racing the beam when it comes to game graphics, and say goodbye to Kristina’s series on USPS technology.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download and savor at your leisure.

Continue reading “Hackaday Podcast 242: Mechanical Math, KaboomBox, And Racing The Beam” →

Simple Hack Lets Smartphone Take Resin Printer Time-Lapses

October 26, 2023 by Dan Maloney 5 Comments

With how cheap they’re getting, everyone seems to be jumping on the resin printer bandwagon. They may not be able to fully replace your trusty old FDM printer, but for certain jobs, they just can’t be beaten. Sadly though, creating those smooth time-lapse videos of your prints isn’t quite as easy to do as it is on their filament-based counterparts.

Not as easy, perhaps, but not impossible. [Fraens] found a way to make time-lapses on any resin printer, and in a wonderfully hacky way. First, you need to find a smartphone, which shouldn’t be too hard, given how often we all tend to upgrade. [Fraens] recommends replacing the standard camera app on the phone with Open Camera, to prevent it from closing during the long intervals with nothing happening. The camera is triggered by any readily available Bluetooth dongle, which is connected via a simple transistor circuit to an Arduino output. To trigger the shutter, a light-dependent resistor (LDR) is connected to one of the microcontroller’s inputs. The LDR is placed inside the bed of the resin printer — an Anycubic Photon in this case — where light from the UV panel used to cross-link the resin can fall on it. A simple bit of Arduino code triggers the Bluetooth dongle at the right moment, capturing a series of stills which are later stitched together using DaVinci Resolve.

The short video below shows the results, which look pretty good to us. There are other ways to do this, of course, but we find the simplicity of this method pleasing.

Continue reading “Simple Hack Lets Smartphone Take Resin Printer Time-Lapses” →

Making Magnetic Tape From Scratch

October 24, 2023 by Jenny List 34 Comments

The use of magnetic tape and other removable magnetic media is now on the wane, leading to scarcity in some cases where manufacture has ceased. Is it possible to produce new magnetic tape if you don’t happen to own a tape factory? [Nina Kallnina] took the effort to find out.

It’s probably one of those pieces of common knowledge, that magnetic media use iron oxides on their surface, which is the same as rust. But the reality is somewhat more complex, as there is more than one iron oxide. We follow [Nina] through this voyage of discovery in a Mastodon thread, as she tries first iron filings, the rust, and finally pure samples of the two iron oxides Fe3O4 and Fe2O3. She eventually achieves a working tape with a mixture of Fe2O3 and iron powder, though its performance doesn’t match manufactured tape. It turns out that there are two allotropes of Fe2O3, and she leaves us as she’s trying to make the one with better magnetic properties.

These results look promising, and while there is evidently a very long way to go before a home-made magnetic coating could replicate the exacting demands of for example a hard drive platter it’s evident that there is something in pursuing this path.

This may be the first time we’ve seen tape manufacture, but we’ve certainly seen extreme measures taken to rejuvenate old tapes.

You’ve Got Mail: Grilled, Scrambled, And Other Delicious Stamps

October 19, 2023 by Kristina Panos 8 Comments

Well, we’re just zipping right through this series, no? So far we’ve looked at various postal machines and how they work to flip mail around, cancel the postage, and sort it, all in a matter of seconds. We explored the first automated post office and found out why it was a failure, and we learned why it all depends on ZIP code. Now, it’s finally time for some really fun stuff: the stamp trivia.

Now I’m no philatelist by any standard, though I do have a few hundred stamps strewn about the house. The danger in philately is that you learn all sorts of cool things about stamps and their history, and you just want to buy more and more of them. So let’s go!

Continue reading “You’ve Got Mail: Grilled, Scrambled, And Other Delicious Stamps” →

Hackaday Podcast Ep 240: An Amazing 3D Printer, A Look Inside Raspberry Pi 5, And Cameras, Both Film And Digital

October 13, 2023 by Dan Maloney 6 Comments

Date notwithstanding, it’s your lucky day as Elliot and Dan get together to review the best hacks of the week. For some reason, film photography was much on our writers’ minds this week, as we talked about ways to digitalize an old SLR, and how potatoes can be used to develop film (is there a Monty Python joke in there?) We looked at a 3D printer design that really pulls our strings, the custom insides of the Raspberry Pi 5, and the ins and outs of both ferroresonant transformers and ham radio antennas. Learn about the SMD capacitor menagerie, build a hydrogen generator that probably won’t blow up, and listen to the differences between a mess of microphones. And that’s not all; the KIM-1 rides again, this time with disk drive support, Jenny tests out Serenity but with ulterior motives, and Kristina goes postal with a deep dive into ZIP codes.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

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

Continue reading “Hackaday Podcast Ep 240: An Amazing 3D Printer, A Look Inside Raspberry Pi 5, And Cameras, Both Film And Digital” →

Sine-wave Speech Demonstrates An Auditory One-way Door

October 7, 2023 by Donald Papp 41 Comments

Sine-wave speech can be thought of as a sort of auditory illusion, a sensory edge case in which one’s experience has a clear “before” and “after” moment, like going through a one-way door.

Sine-wave speech (SWS) is intentionally-degraded audio. Here are the samples, and here’s what to do:

Choose a sample and listen to the sine-wave speech version (SWS). Most people will perceive an unintelligible mix of tones and beeps.
Listen to the original version of the sentence.
Now listen to the SWS version again.

Most people will hear only some tones and beeps when first listening to sine-wave speech. But after hearing the original version once, the SWS version suddenly becomes intelligible (albeit degraded-sounding).

These samples were originally part of research by [Chris Darwin] into speech perception, but the curious way in which one’s experience of a SWS sample can change is pretty interesting. The idea is that upon listening to the original sample, the brain — fantastic prediction and learning engine that it is — now knows better what to expect, and applies that without the listener being consciously aware. In fact, if one listens to enough different SWS samples, one begins to gain the ability to understand the SWS versions without having to be exposed to the originals. In his recent book The Experience Machine: How Our Minds Predict and Shape Reality, Andy Clark discusses how this process may be similar to how humans gain fluency in a new language, perceiving things like pauses and breaks and word forms that are unintelligible to a novice.

This is in some ways similar to the “Green Needle / Brainstorm” phenomenon, in which a viewer hears a voice saying either “green needle” or “brainstorm” depending on which word they are primed to hear. We’ve also previously seen other auditory strangeness in which the brain perceives ever-increasing tempo in music that isn’t actually there (the Accelerando Illusion, about halfway down the list in this post.)

Curious about the technical details behind sine-wave speech, and how it was generated? We sure hope so, because we can point you to details on SWS as well as to the (free) Praat software that [Chris] used to generate his samples, and the Praat script he wrote to actually create them.