No TP? No Problem!

November 16, 2023 by 42 Comments

Among First World Problems, there can be few worse than running out of toilet paper. The horror! If you’re not able to do as we did yesterday and borrow a pack until more can be bought, then you’re not without options. A handy copy of the Daily Mail could be cut into squares and hung up in your Smallest Room, or you can even make your own with the help of this handy instructional video from [whoisandrewfahmy]. It appears from a casual search to be one of many such guides that appeared during the pandemic when the bog roll supply was seen as endangered, but it’s still interesting simply as a diversion into how something is made.

The process is surprisingly straightforward, starting with scrap paper, which is shredded and soaked before being boiled to break down to pulp. The pulp is then emulsified, and some body oil is added to remove the sandpaper-on-the-butt experience before being spread between a sheet and a piece of window screen to be ironed dry. It’s an energy-intensive process, so the Daily Mail is likely to be an easier stopgap if no friends can lend you a few rolls, but it’s left us here curious about papermaking. The butts of Hackaday may be safe from homemade TP, but that’s not to say that it wouldn’t be interesting to make other paper products. Check out the video below.

Of course, back in April 2020 we had our own solution to the pandemic toilet paper shortage. After you make your bespoke dunny roll, how can you wind it into a nice roll? Don’t worry. We got you.

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ColorReplica Is A Rainbow At Your Fingertips

November 16, 2023 by 15 Comments

Have you ever wanted to match paint to the color of a pillow, or make a website where the primary color matches your favorite shade of electrolytic capacitor? Then ColorReplica is the project for you.

At the heart of this build are two ESP32s, one of which controls the color picker, and the other lights up the 18 WS2812 LEDs and displays information on the OLED screen.

ColorReplica has two modes, ColorPicker and ColorCube. In ColorPicker mode, you just choose what color you want, adjust the brightness level, and choose between static and dynamic modes for the LEDs. [CiferTech] used the ESP32 touch pins extended to pads on the PCB to control different menu variables, which is a nice touch.

In ColorCube mode, there’s a secondary circuit with a color sensor an another ESP32. Once detected, it transmits the color data to the main device at the push of a button. The RGB LEDs turn that color, and shows the RGB, HEX, and HSV values on the OLED screen. If you’d like to make one of these yourself, everything is available on GitHub.

Want something a big more tangible? Check out this color picker that types HEX codes for you.

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Umbrella Antenna Protects You From Rain, But Not The Way You Think

November 16, 2023 by 8 Comments

You never know when you’ll be called upon to [MacGyver] your way out of an emergency. We can’t imagine what kind of situation would call for whipping up a satellite ground station for NOAA weather satellites from junk, but hey, it could happen.

And when it does, you’ll be ready — as long as you have an umbrella, some foil tape, and various bits and bobs like wire and an RTL-SDR dongle. That’s what [saveitforparts] used for his field-expedient build, at least in the first instance; as you can imagine, builds like this take a lot of tweaking to get right. The umbrella and foil tape form the main reflector for the antenna, with a pie tin, a scrap of wire, and some random twigs being used to build the antenna’s helical feed. Attached to a SAWbird LNA/filter and an RTL-SDR plugged into a dodgy second-hand phone, he was able to get at least some kind of data from one of the GOES satellites, but it wasn’t great.

Switching the feed to a commercially available log periodic antenna worked much better, with some partial decodes of weather map data. Actually, getting anything at all with a setup like this is impressive enough for us to call it a win. It shows that the umbrella approach to antennas is valid; but then again, we already knew that.

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A 3D Printed Grinder For Printed Lens Blanks

November 16, 2023 by 20 Comments

When one thinks of applications for 3D printing, optical components don’t seem to be a good fit. With the possible exception of Fresnel lenses, FDM printing doesn’t seem up to the job of getting the smooth surfaces and precision dimensions needed to focus light. Resin printing might be a little closer to the mark, but there’s still a long way to go between a printed blank and a finished lens.

That gap is what [Fraens] aims to fill with this homebrew lens grinding machine. It uses the same basic methods used to grind and polish lenses for centuries, only with printed components and lens blanks. The machine itself consists of a motorized chuck for holding the lens blank, plus an articulated arm to hold the polishing tool. The tool arm has an eccentric drive that wobbles the polishing tool back and forth across the blank while it rotates in the chuck. Lens grinding requires a lot of water and abrasive, so a large bowl is provided to catch the swarf and keep the work area clean.

Lens blanks are printed to approximately their finished dimensions using clear resin in an SLA printer. [Fraens] spent a lot of time optimizing the printing geometry to minimize the number of print layers required. He found that a 30° angle between the lens and the resin pool worked best, resulting in the clearest blanks. To polish the rough blanks, a lapping tool is made from polymer modeling clay; after baking it dry, the tool can hold a variety of pads and polishing compounds. From there it’s just a matter of running the blank through a range of abrasives to get the desired final surface.

Are the lenses fantastic? Well, they’re probably not going to make it into fine optical equipment, but they’re a lot better than you might expect. Of course, there’s plenty of room for improvement; better resins might result in clearer blanks, and perhaps degassing the uncured resin under vacuum might help with bubbles. Skipping the printed blanks and going with CNC-machined acrylic might be worth a try, too.

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Tech In Plain Sight: What Does A Yellow Light Mean?

November 16, 2023 by 58 Comments
Ghigleri’s traffic light

The traffic light is a ubiquitous feature of modern life and is quite old — dating back to 1868 London, although that device was a modified railroad semaphore operated by a policeman, but it was the same idea. The initial test of the signal proved disastrous.

The semaphore had gas lamps to illuminate the signs in the dark. A gas leak caused one of the lamps to explode, badly burning the operator and ending the nascent invention for a while. In 1910, American inventor Ernest Sirrine worked out an automatically controlled traffic signal. Two years later, Lester Wire, a police officer, developed a different version powered by overhead trolley wires to light the signal. A 1917 patent by William Ghiglieri also had two lights — red and green. But where was the yellow light?

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Probably The Largest Selfie Camera In The World

November 16, 2023 by No comments

Most readers will have some idea of how a camera works, with a lens placed in front of a piece of film or an electronic sensor, and the distance between the two adjusted until the images is in focus. The word “camera” is a shortening of “camera obscura”, the Latin for “dark room”, as some early such devices were darkened rooms in which the image was projected onto a rear wall. [David White], a lecturer at Falmouth University in the UK has created a modern-day portable camera obscura using a garden gazebo frame, and uniquely for a camera obscura, it can be used to take selfies.

As might be expected the gazebo frame covered with a dark fabric forms the “room”, and the surface on which the image is formed comes from a projection screen. The lens is a custom-made 790 mm f/5.4, not exactly the type of lens found off-the-shelf. The selfie part comes from a Canon digital camera inside the gazebo focused on the frame, using its Wi-Fi control app a subject can sit at the appropriate point in front of the lens and take the selfie as they see fit.

The resulting images have a pleasing ethereal feel to them, and while it’s definitely not the most practical taker of snaps it’s still very much a camera to be impressed by. We’d be curious to see how it would perform as a pinhole camera, and even though it’s nowhere near the 2006 record pinhole image taken using an abandoned US Marine Corps aircraft hangar we think it would still deliver when given enough light. Meanwhile this isn’t the first time we’ve shown you a camera obscura, here’s one using the back of a U-Haul truck.

Lessons In Mass Production From An Atari Punk Console

November 16, 2023 by 7 Comments

Sometimes the most interesting part of a project isn’t the widget itself, but what it teaches you about the manufacturing process. The story of the manufacturing scale-up of this Atari Punk Console and the lessons learned along the way is a perfect example of this.

Now, don’t get us wrong — we love Atari Punk Consoles. Anything with a couple of 555s that bleeps and bloops is OK in our books. But as [Adam Gulyas] tells the tale, the point of this project was less about the circuit than about the process of making a small batch of something. The APC was low-hanging fruit in that regard, and after a quick round of breadboarding to decide on component values, it was off to production. [Adam] was shooting for 20 units, each in a nice enclosure and a classy package. PCB assemblies were ordered, as were off-the-shelf plastic enclosures, which ended up needing a lot of tweaking. [Adam] designed custom labels for the cases, itself a fraught job; glossy label stock and button bezels apparently don’t mix.

After slogging through the assembly process, boxing the units for shipping was the next job. [Adam] sourced jewelry boxes just a bit bigger than the finished APCs, and rather than settle for tissue paper or packing peanuts, designed an insert to hold the units snugly. That involved a lot of trial and error and a little bit of origami-fu, and the results are pretty nice. His cost per unit came out to just a hair over $20 Canadian, including the packaging, which is actually pretty remarkable for such a short production run.

[Adam] includes a list of improvements for larger-scale runs, including ordering assembled PCBs, outsourcing the printing processes, and getting custom boxes made so no insert is needed. Any way you cut it, this production run came out great and teaches us all some important lessons.