Coffee Stirrers Act As Lens For This Digital Straw Camera

What happens when you mix over 23,000 coffee stirrers and a Raspberry Pi camera together? Probably nothing except for a mess, unless you very specifically pack the plastic straws and orient the camera just right. In that case, you get this very cool lenless digital straw camera that takes artfully ghostly images.

Image of Yoda photographed through many straws

Actually, lensless is a bit of a reach for [Adrian Hanft]’s creation. While the camera he’s using to grab the image has a lens, the objective, for lack of a better term, is just a tightly packed bundle of straws. We’ve seen this approach to photography before, but there the camera used film placed at the back of the straw bundles to capture the pixelated image.

Here, a ground glass screen stands in for the film; a long lightproof box behind that provide a place to mount a camera to capture the images. Cleverly, [Adrian] built the camera mount from Lego, allowing cameras and lenses to be quickly swapped out. A Nintendo gamepad controller talks to custom software running on a Raspberry Pi and allows the photographer to control exposure and scroll through pictures using a smartphone as a display. There’s a short build video below, for those who can’t get enough of straw-packing techniques.

As with the film version of this camera, we just love the look of the photographs that come from this — the texture of the straw honeycomb and the defocused subject make for a striking effect.

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Raspberry Pi Spigot Puts Digits Of Pi On Tap

What did you do for Pi Day? Play with your Raspberry Pi 400? Eat some pizza or other typically round objects and recite all nine digits you’ve got memorized? That’s about where we were at this year. But not [bornach], no. [bornach] went all out and built a spigot that spews digits of Pi well past the first nine decimal places.

This clever spigot sculpture implements the spigot algorithm for generating digits of Pi one-by-one in a stream on to a chain of 8×8 matrices, and does so using a Raspberry Pi (of course). The point of the spigot algorithm is to store as few numbers as possible at any given time by reusing variables. We love the way the digits materialize on the matrix, almost as if they are ink being activated by water. Be sure to check out the build and demo video after the break.

That 10k pot on the top really does control the spigot — since the Pi has no ADC, [bornach] is using the potentiometer to charge a capacitor and using the time it takes to reach the threshold to decide whether the faucet is open or closed. There are a couple of hacks at play here, including the Popsicle-stick LED matrix bracing and the HAT [bornach] fashioned so the daisy-chained 8×8 LED modules could interface with the Pi.

We love Raspberry Pis of all eras around here, especially the darling new Pico. Diminutive as it may be, the Pico can be sliced even smaller with a hacksaw if you don’t mind losing a few GPIO pins.

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Hackaday Links: March 14, 2021

It’ll be Pi Day when this article goes live, at least for approximately half the globe west of the prime meridian. We always enjoy Pi Day, not least for the excuse to enjoy pie and other disc-shaped foods. It’s also cool to ponder the mysteries of a transcendental number, which usually get a good treatment by the math YouTube community. This year was no disappointment in this regard, as we found two good pi-related videos, both by Matt Parker over at Standup Maths. The first one deals with raising pi to the pi to the pi to the pi and how that may or may not result in an integer that’s tens of trillions of digits long. The second and more entertaining video is a collaboration with Steve Mould which aims to estimate the value of pi by measuring the volume of a molecular monolayer of oleic acid floating on water. The process was really interesting and the results were surprisingly accurate; this might make a good exercise to do with kids to show them what pi is all about.

Remember basic physics and first being exposed to the formula for universal gravitation? We sure do, and we remember thinking that it should be possible to calculate the force between us and our classmates. It is, of course, but actually measuring the attractive force would be another thing entirely. But researchers have done just that, using objects substantially smaller than the average high school student: two 2-mm gold balls. The apparatus the Austrian researchers built used 90-milligram gold balls, one stationary and one on a suspended arm. The acceleration between the two moves the suspended ball, which pivots a mirror attached to the arm to deflect a laser beam. That they were able to tease a signal from the background noise of electrostatic, seismic, and hydrodynamic forces is quite a technical feat.

We noticed a lot of interest in the Antikythera mechanism this week, which was apparently caused by the announcement of the first-ever complete computational model of the ancient device’s inner workings. The team from University College London used all the available data gleaned from the 82 known fragments of the mechanism to produce a working model of the mechanism in software. This in turn was used to create some wonderful CGI animations of the mechanism at work — this video is well worth the half-hour it takes to watch. The UCL team says they’re now at work building a replica of the mechanism using modern techniques. One of the team says he has some doubts that ancient construction methods could have resulted in some of the finer pieces of the mechanism, like the concentric axles needed for some parts. We think our friend Clickspring might have something to say about that, as he seems to be doing pretty well building his replica using nothing but tools and methods that were available to the original maker. And by doing so, he managed to discern a previously unknown feature of the mechanism.

We got a tip recently that JOGL, or Just One Giant Lab, is offering microgrants for open-source science projects aimed at tackling the problems of COVID-19. The grants are for 4,000€ and require a minimal application and reporting process. The window for application is closing, though — March 21 is the deadline. If you’ve got an open-source COVID-19 project that could benefit from a cash infusion to bring to fruition, this might be your chance.

And finally, we stumbled across a video highlighting some of the darker aspects of amateur radio, particularly those who go through tremendous expense and effort just to be a pain in the ass. The story centers around the Mt. Diablo repeater, an amateur radio repeater located in California. Apparently someone took offense at the topics of conversation on the machine, and deployed what they called the “Annoy-o-Tron” to express their displeasure. The device consisted of a Baofeng transceiver, a cheap MP3 player loaded with obnoxious content, and a battery. Encased in epoxy resin and concrete inside a plastic ammo can, the jammer lugged the beast up a hill 20 miles (32 km) from the repeater, trained a simple Yagi antenna toward the site, and walked away. It lasted for three days and while the amateurs complained about the misuse of their repeater, they apparently didn’t do a thing about it. The jammer was retrieved six weeks after the fact and hasn’t been heard from since.

Heavy Raspberry Pi User? Keep An HDMI-to-USB Capture Device Around

Here’s a simple tip from [Andy], whose Raspberry Pi projects often travel with him outside the workshop: he suggests adding a small HDMI-to-USB video capture device to one’s Raspberry Pi utility belt. As long as there is a computer around, it provides a simple and configuration-free way to view a Raspberry Pi’s display that doesn’t involve the local network, nor does it require carrying around a spare HDMI display and power supply.

Raspberry Pi’s display, viewed on a Mac as if it were a USB webcam. No configuration required.

The usual way to see a Pi’s screen is to either plug in an HDMI display or to connect remotely, but [Andy] found that he didn’t always have details about the network where he was working (assuming a network was even available) and configuring the Pi with a location’s network details was a hassle in any case. Carrying around an HMDI display and power supply was also something he felt he could do without. Throwing a small HDMI-to-USB adapter into his toolkit, on the other hand, has paid off for him big time.

The way it works is simple: the device turns an HDMI video source into something that acts just like a USB webcam’s video stream, which is trivial to view on just about any desktop or laptop. As long as [Andy] has access to some kind of computer, he can be viewing the Pi’s display in no time.

Many of his projects (like this automated cloud camera timelapse) use the Pi camera modules, so a quick way to see the screen is useful to check focus, preview video, and so on. Doing it this way hit a real sweet spot for him. We can’t help but think that one of these little boards could be a tempting thing to embed into a custom cyberdeck build.

Adventures In Overclocking: Which Raspberry Pi 4 Flavor Is Fastest?

There are three different versions of the Raspberry Pi 4 out on the market right now: the “normal” Pi 4 Model B, the Compute Module 4, and the just-released Raspberry Pi 400 computer-in-a-keyboard. They’re all riffing on the same tune, but there are enough differences among them that you might be richer for the choice.

The Pi 4B is easiest to integrate into projects, the CM4 is easiest to break out all the system’s features if you’re designing your own PCB, and the Pi 400 is seemingly aimed at the consumer market, but it has a dark secret: it’s an overclocking monster capable of running full-out at 2.15 GHz indefinitely in its stock configuration.

In retrospect, there were hints dropped everywhere. The system-on-a-chip that runs the show on the Model B is a Broadcom 2711ZPKFSB06B0T, while the SOC on the CM4 and Pi 400 is a 2711ZPKFSB06C0T. If you squint just right, you can make out the revision change from “B” to “C”. And in the CM4 datasheet, there’s a throwaway sentence about it running more efficiently than the Model B. And when I looked inside the Pi 400, there was this giant aluminum heat spreader attached to the SOC, presumably to keep it from overheating within the tight keyboard case. But there was one more clue: the Pi 400 comes clocked by default at 1.8 GHz, instead of 1.5 GHz for the other two, which are sold without a heat-sink.

Can the CM4 keep up with the Pi 400 with a little added aluminum? Will the newer siblings leave the Pi 4 Model B in the dust? Time to play a little overclocking!

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Autonomous Multi-Task Performing Robot

[Ruchir] has been pretty into robotics for a while now and has always been amused by the ever-popular obstacle avoiding robot, but wanted something that could do more. So, like any good hacker, he decided to build something himself.

He wanted to incorporate all the popular beginner robot capabilities into a single invention. His robot can follow a line, detect an obstacle, and retrieve an object without switching between modes. It can even follow another robot, which is pretty neat.

His robot has a lot of the hardware you would expect. It uses a Raspberry Pi for all the heavy image processing, has optical sensors for line following and obstacle avoidance, and includes a speaker for audio feedback. What’s especially cool is the impressive interface, called the Regbot GUI, that [Ruchir] is using with his robot. According to the Wiki page, the Regbot GUI appears to accompany an educational robotics platform developed by Professor Jens Christian Andersen of the Technical University of Denmark for teaching controls to engineering students. [Ruchir] was able to adapt the GUI to his particular bot no problem.

Using the Regbot GUI, [Ruchir] can monitor all the robot’s sensor data in real-time (accelerometer, gyroscope, distance sensor, servo, encoder, etc.), dynamically adjust its calibration settings if needed, or even provide a universal killswitch in case the unthinkable happens. We’d say it’s definitely worth a look before you embark on your next robotics project.

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The Internet Of Bubble Machines

Everyone loves a good bubble machine. These oddly satisfying novelty items have brought children and adults mindless entertainment since their inception. [8BitsAndAByte] had the same thought, but wanted to give their bubble machine a taste of the IoT-age.

First, they modified an off-the-shelf bubble machine with a Raspberry Pi and relay module. The Pi can easily trigger the bubbling mechanism by controlling power to the machine using the relay. Seems simple enough. The part of this project that might be a bit more unfamiliar to you is controlling the robot over the internet using remo.tv.

Remo.tv is a robot controller platform that’s both free and open-source, and we’ve seen [8BitsAndAByte] take advantage of this web controller before. Seems like they’re really getting the hang of it. Their writeup links to a detailed setup guide for configuring the Pi, so hopefully, that’s not too much trouble.

Couple the IoT setup with a Pi camera and you’ve got a live stream that’s admittedly oddly satisfying to watch with or without the bubbles.

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