Lessons in Disposable Design from a Cheap Blinky Ball

Planned obsolescence, as annoying as it is when you’re its victim, still has to be admired. You can’t help but stand in awe of the designer who somehow managed to optimize a product to live one day longer than its warranty period. Seriously, why is it always the next day?

The design of products that are never intended to live long enough to go obsolete must be similarly challenging, and [electronupdate] did a teardown of a cheap LED blinky toy to see what’s involved. You’ve no doubt seen these seizure-triggering silicone balls before, mostly at checkout counters and the like where they’re sold at prices many hundreds of times what it took to make them. This particular device, which seems representative of the species, has two bright LEDs, a small controller chip, a trio of button cells for power, and a springy switch to activate it. All this is mounted to a cheap scrap of phenolic resin PCB, with the controller chip and one of the LEDs covered by a blob of clear epoxy.

This teardown one-ups most others, as [electronupdate] disrobes the chip and points a microscope at the die; the video below shows just how few transistors are employed and proposes a likely circuit. Everything about this ball just oozes cheapness, and it’s likely these things cost essentially nothing to build. Which makes sense for something destined for the landfill within a week or so.

Yes, this annoying blinky-thing is low-end garbage, but there are still design lessons to be learned from it. Anything that’s built for a broad market has to be built to a price point, and understanding those constraints is important to understanding how planned obsolescence works.

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H2gO Keeps Us from Drying Out

The scientific community cannot always agree on how much water a person needs in a day, and since we are not Fremen, we should give it more thought than we do. For many people, remembering to take a sip now and then is all we need and the H2gO is built to remind [Angeliki Beyko] when to reach for the water bottle. A kitchen timer would probably get the job done, but we can assure you, that is not how we do things around here.

A cast silicone droplet lights up to show how much water you have drunk and pressing the center of the device means you have taken a drink. Under the hood, you find a twelve-node NeoPixel ring, a twelve millimeter momentary switch, and an Arduino Pro Mini holding it all together. A GitHub repo is linked in the article where you can find Arduino code, the droplet model, and links to all the parts. I do not think we will need a device to remind us when to use the bathroom after all this water.

Another intrepid hacker seeks to measure a person’s intake while another measures output.

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This 3D Printed Syringe Static Mixer Does It All

One trick for getting the bubbles out of freshly mixed 2-part epoxy, aka degassing, is to go over it gently with the flame from a propane torch. But both the mixing and degassing take time. [Gianteye] came up with a 3D printed dual-syringe static mixing system which speeds up the process. He used it with silicone to get the difficult steps out of the way quickly for his hands-on soft robotics class, allowing the students to focus more on the matter at hand. But we figure most readers might use it for epoxy.

Mixing tube interior
Mixing tube interior

If you’ve bought those 2-part epoxy syringes available in stores before then you’ll know that they usually come with two syringes, each filled with one of the two parts to be mixed. Depressing the syringes causes each part to come out of its own tube. It’s then your job to mix them together and degas the result.

[Gianteye’s] system consists of 3D printed parts and two syringes.  Models for the 3D printing are available on his Thingiverse page and the syringes can be found online. Some of the 3D printed parts help you first fill and degas the syringes. You then attach a 3D printed mixing tube to the ends of the syringes. This tube serves two purposes. When the syringe’s plungers are depressed, both parts of the material are forced through the tube and extruded out. But on their way through, both parts pass through eight helices which form 180° turns and mix the parts together. Out comes the portioned, mixed and degassed material which can go straight into a mold or to wherever you need it.

The mixing tube was designed for one-time use but [Gianteye] discovered during an evaluation that it can be reused if you pull out any cured material and purge it. The evaluation involved silicone though. With hardened epoxy, you’ll probably have to use a new tube each time.

Check out the full details of his system in the video below, including both assembly and usage.

If you’re looking for a metallic look for something without wanting to cast metal than have a look at our own [Gerrit Coetzee’s] article about cold casting wherein he makes some very nice looking parts.

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Custom Buttons For Your Game Controller

Console gamers have relatively few options when it comes to hardware hacking, unless they wish to partake of some extreme modifications that threaten the very integrity of their machines. So without reaching for a Dremel, how can you insert a little individuality into the same standard components all your friends have?

It seems one answer is to customise your controller with some different buttons. There are commercial outfits that will supply your needs in this direction, but they aren’t always cheap, and plenty of older machines have no products available. This isn’t  a problem for [RockerGaming] though, who shows us how to cast your own set of custom buttons using a silicone mold taken from the originals.

The video is a step-by-step walkthrough of the molding process that could just as easily be applied to any other small plastic parts and is not unique to console buttons. The subjects come from a Sega Saturn controller, in the video a beige model, which raises a passing interest among European Hackaday scribes who remember the Saturn as a black console.

We see the preparation of the original buttons and mold. An acrylic golf ball trophy display case is pressed into service. (Who knew those were even a thing!) A dye is added to the two-part silicone to provide a visual mixing aid, and once the cast mold is separated from the buttons the final resin is poured into it. The cloned buttons are tidied up underneath with a Dremel, and the controller is reassembled.

A set of custom buttons will not improve your gaming, but underlying this is the fact that resin casting is a useful skill. It’s somewhere we’ve been before in depth, so it’s worth reading our guide from back in 2016.

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Using Lasagna to Make Cost-Saving Molds

Building a one-off prototype is usually pretty straightforward. Find some perfboard and start soldering, weld up some scrap metal, or break out the 3D printer. But if you’re going to do a production run of a product then things need to have a little more polish. In [Eric Strebel]’s case this means saving on weight and material by converting a solid molded part into something that is hollow, with the help of some lasagna.

What [Eric] walks us through in this video is how to build a weep mold. First, the solid part is cast in silicone. Using the cast, some “sheet clay” is applied to the inside which will eventually form the void for the new part’s walls. The clay needs to be flush with the top of the mold, though, and a trick to accomplish this task is to freeze the mold (next to the lasagna) which allows the clay to be scraped without deforming.

From there, the second half of the mold is poured in, using special channels that allow the resin to “weep” out of the mold (hence the name). This two-part process creates a much more efficient part with thin walls, rather than the expensive solid prototype part.

[Eric] is no stranger around these parts, either. He’s an industrial designer with many tips and tricks of the profession, including a method for building a machining tool out of a drill press and a vise as well as some tips for how to get the most out of a low-volume production run of a product you might be producing.

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Exploring Options for DIY Waterproofing

TL;DR — Don’t use silicone to pot electronics.

That’s the conclusion [GreatScott!] comes to after trying out several methods for waterproofing electronics. His efforts stem from a recent video in which he discovered that water and electricity sometimes actually do mix, as long as the water is distilled and the electronics in the drink are relatively simple. He found that the main problem was, unsurprisingly, electrolytic corrosion, so he set out to experiment with various waterproofing coatings. In a series of careful experiments he goes through the pros and cons of both conformal coatings and potting compounds. The conformal tests used simple clear nail polish on an ESC board; that worked pretty well, but it was a little hard to reach all the nooks and crannies. He also tried potting with a thick black silicone compound, but that ended up never really curing in the middle. A final attempt with legitimate two-part epoxy potting compound sealed up the ESC tight, although we doubt the resulting brick would perform well on a quadcopter.

If you want to explore potting a bit further, check out this introduction to the basics.

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Tricked-Out Tablet Becomes Workbench Tool

The workbench of the typical electronics hobbyist today would probably be largely recognizable by Heathkit builders back in the 60s and 70s. But where the techs and tinkerers of yesteryear would have had a real dead-tree SAMS Photofact schematic spread out on the bench, today you’ll get more use out of a flat-screen display for data sheets and schematics, and this handy shop Frankentablet might be just the thing to build.

Tablets like the older Nexus 9 that [enginoor] used as the basis for this build have a little bit of a form-factor problem because unlike a laptop, a tablet isn’t very good at standing up on its own. To fix that, they found a suitable silicone skin for the Nexus, and with some silicone adhesive began bedazzling the back of the tablet. A bendy tripod intended for phones was added, and with the tablet able to stand on its own they maximized the USB port with a right angle adapter and a hub. Now the tablet has a USB drive, a mouse, and a keyboard, ready for perusing data sheets online. And hackers of a certain age will appreciate the eyeball-enhancing potential of the attached USB microscope.

[enginoor]’s bench tablet is great, but we’ve seen full-fledged bench PCs before too. Take your pick — wall mounted and floating, or built right into the workbench.

Thanks to [ccvi] for the tip.