Day: January 9, 2023

Wipe On, Wipe Off: Make Your Own Rain Repellent

January 9, 2023 by 55 Comments

Once upon a time, we drove an old six-volt VW Beetle. One sad day, the wiper motor went out, and as this happened before the Internet heyday, there were no readily-available parts around that we were aware of. After briefly considering rubbing a potato on the windshield as prescribed by the old wives’ tale, we were quite grateful for the invention of Rain-X — a water-repelling chemical treatment for car windshields.

Boy would we have loved to know how to make it ourselves from readily-available chemicals. As you’ll see in the video below, it doesn’t take much more than dimethicone, sulfuric acid, and a cocktail of alcohols. [Terry] starts with dimethicone, which he activates with a healthy dose of concentrated sulfuric acid, done under the safety of an exhaust hood. After about 20 minutes on the stir mix-a-lot plate, [Terry] added ethanol and isopropyl alcohols. Finally, it was off to the garage with the mixture in a spray bottle.

After meticulously cleaning the windshield, [Terry] applied the solution in small areas and rubbed it in with a towel to create a thin bond between it and the glass. This creates a perfectly normal haze, which can be removed after a bit with a clean towel.

If you just love listening to your windshield wipers, at least make them move to a beat.

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IoT Archaeology Leads To API Resurrection

January 9, 2023 by 21 Comments

What happens when someone’s personal project is turned into a startup which becomes something of a publicity darling, then collapses with very little product shipped and takes all its customers’ money with it?

That’s the subject of a blog post from [Kevin Chung], who investigated the legacy of NYCTrainSign, a company whose product was an LED NYC subway sign and which has become a meme byword for a startup scam. Along the way he found himself reverse engineering its API, and eventually even purchasing the expired domain name to resurrect the API for any NYCTrainSigns that may still be out there.

Securing a second-hand NYCTrainSign, he dismantled it to see what made it tick. Inside the handmade wooden case was an array of LED panels, driven by a Raspberry Pi 3 and an Adafruit LED panel HAT. This gave pause for thought, as the component choice gives rise to a very high BoM cost which was unsustainable given their habit of steep discounts.

The software proves straightforward enough to reverse engineer, and since the original domain was for sale he bought it and set up a replacement API. Do you have one of the few signs that made it to customers? Now you can run it again.

The rest of the piece tells a tale that will be familiar to startup veterans: one of far too much marketing, too many bosses, and too little engineering to create a viable product. The founders remain tight-lipped about what happened and where the money went, but since there are few more efficient money pits than a badly-run startup, it’s more likely that ill-advised spending is to blame than someone running off with suitcases of cash.

If you’d like a public transit sign without the dodgy start-up, we’ve got you covered.

Clever Mechanism Makes A Linear Control From A Rotary Hall Sensor

January 9, 2023 by 81 Comments

Every once in a while we stumble across something so simple yet so clever that we just have to call it out. This custom linear Hall effect sensor is a perfect example of this.

By way of backstory, [Nixieguy], aka [The Electronic Mercenary], offers up a relatable tale — in the market for suitable hardware to make the game Star Citizen more enjoyable, and finding the current commercial joystick offerings somewhat wanting, he decided to roll his own controllers. This resulted in the need for a linear sensor 100 mm in length, the specs for which — absolute sensing, no brushes or encoders, easily sourced parts — precluded most of the available commercial options, like linear pots. What to do?

The solution [Nixieguy] settled on was to use a Hall effect sensor and a diametrally magnetized neodymium ring magnet. The magnet is rotated through 180 degrees by a twisted aluminum bar, which is supported in a frame by bearings. A low-friction slider with a slot captures the bar; moving the slider along the length of the control rotates the bar, which rotates the magnet, which allows the Hall sensor to measure the angle of the magnetic field. Genius!

The parts for the prototype sensor are all made from 0.8-mm aluminum sheet stock and bent to shape. The video below shows the action better than words can describe it, and judging by the oscilloscope trace, the output of the sensor is pretty smooth. There’s clearly a long way to go to tighten things up, but the basic mechanism looks like a clear win to us.

Hats off to [Nixieguy] for this one, which we’ll surely be following for more developments. In the meantime, if you need to brush up on the Hall effect, [Al Williams] did a nice piece on that a while back.

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You Can Now Fix Your Deere

January 9, 2023 by 29 Comments

Over the last few years we have brought you many stories about John Deere tractors, and how their repair has been locked down such that only manufacturer-authorised technicians can work on them. They’ve become a poster child in the battle for the right to repair, a symbol of the worst practices. Finally now we can bring you some good news of sorts, as the agricultural giant has signed a memorandum of understanding with the American Farm Bureau Federation to ensure that their products will henceforth be repairable by people without Deere approval.

We can’t imagine that Deere will have taken this step willingly, and while we’d like to imagine that consumer protests in favour of right-to-repair have hit their mark, we’re guessing that it’s more of an economic pressure at work alongside the threat of legislation outside their native America. If farmers getting caught out waiting for a Deere van to arrive while their crop withers in the field wasn’t enough, when the price of a second-hand tractor without the DRM outstrips that of a newer one with it, eventually the sales of new tractors will also suffer.

So this is good news, and we’re guessing that other agricultural manufacturers doing the same DMCA practices will now follow suit. But it’s not a complete victory. The problem starts not with the DMCA restriction itself, but with the extension of the machine’s computer system into every part, including those many parts which simply don’t need it. It’s not a complete victory if anyone can now use the software to register a new hydraulic valve with the system; instead that hydraulic valve should not have to be authorised in the first place. It’s this creeping unnecessary complexity which is the true enemy of right-to-repair, and we shouldn’t forget that.

Header image: Dwight Sipler, CC BY 2.0.

3d printed tiny gym in a box with mirror and led strip lighting

Get Pumped For This Miniature Gym

January 9, 2023 by 5 Comments

[Duncan McIntyre] lives in the UK but participated in a secret Santa gift exchange for his Dutch friends’ Sinterklaas celebration. In traditional maker fashion, [Duncan] went overboard and created a miniature gym gift box, complete with flashing lights, music and a motorized lid.

[Duncan] used [TanyaAkinora]’s 3D printed tiny gym to outfit the box with tiny equipment, with a tiny mirror added to round out the tiny room. An ATmega328P was used as the main microcontroller to drive the MP3 player module and A4988 stepper motor controller. The stepper motor was attached to a drawer slide via a GT2 timing belt and pulley to actuate the lid. Power is provided through an 18V, 2A power supply with an LM7805 providing power to the ATmega328P and supporting logical elements. As an extra flourish, [Duncan] added some hardware audio signal peak detection, fed from the speaker output, which was then sampled by the ATmega328P to be able to flash the lights in time with the playing music. A micro switch detects when the front miniature door is opened to begin the sequence of lights, song and lid opening.

[Duncan] provides source on GitHub for those curious about the Arduino code and schematics. We’re fans of miniature pieces of ephemera and we’ve featured projects ranging from tiny 3D printed tiny escalators to tiny arcade cabinets.

Video after the break!

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All About USB-C: Power Delivery

January 9, 2023 by 64 Comments

USB-C eliminates proprietary barrel plug chargers that we’ve been using for laptops and myriads of other devices. It fights proprietary phone charger standards by explicitly making them non-compliant, bullying companies into making their devices work with widely available chargers. As a hobbyist, you no longer need to push 3 A through tiny MicroUSB connectors and underspecced cables to power a current-hungry Pi 4. Today, all you need is a USB-C socket with two resistors – or a somewhat special chip in case the resistors don’t quite get you where you want to be.

You get way more bang for your buck with USB-C. This applies to power too; after all, not all devices will subsist on 15 W – some will want more. If 15 W isn’t enough for your device, let’s see how we can get you beyond.

Reaching Higher

USB-C power supplies always support 5 V and some are limited to that, but support for higher voltages is where it’s at. The usual voltage steps of USB-C are 5 V, 9 V, 15 V and 20 V ; 12V support is optional and is more of a convention. These steps are referred to as SPR, and EPR adds 28 V, 36 V and 48 V steps into the mix – for up to 240 W; necessitating new cables, but being fully backwards and forwards compatible, and fully safe to use due to cable and device checks that USB-C lets you perform.

A charger has to support all steps below its highest step, which means that 20 V-capable chargers also have to support 5 V, 9 V, and 15 V as well – in practice, most of them indeed do, and only some might skip a step or two. You can also get voltages in-between, down to 3.3 V, even, using a PD standard called PPS (or the AVS standard for EPR-range chargers) – it’s not a requirement, but you’ll find that quite a few USB-C PSUs will oblige, and PPS support is usually written on the label. Continue reading “All About USB-C: Power Delivery” →

A blue Mercedes SLS AMG sports car body with bicycle wheels. The gull wing is open to reveal the spartan interior and the hood is open to reveal an empty engine compartment since this is actually a bike.

SLS AMG Velomobile

January 9, 2023 by 14 Comments

Many gearheads dream of owning a supercar, but their exorbitant prices make them unattainable for all but the most affluent. [Andrzej Burek] decided to make his dreams come true by building his own supercar with a human-powered twist. [YouTube]

At first glance, [Burek]’s SLS AMG looks like the real thing. Pop the hood, and you’ll find this “car” is missing it’s V8 which has been replaced by a beefy speaker pumping out engine sounds from any car you choose. Both driver and passenger can provide propulsion for the sociable tandem, and the power is routed through a differential to the rear wheels. [Burek] decided to install the differential to make installing power assist motors simpler in future revisions of this quadracycle.

[Burek] said it’s taken him four years from buying the first component to the bike’s status in the video after the break. Other than the front and rear bumpers, he built the body himself out of fiberglass to learn how to work with the material. He welded the frame himself as well, and, in a testament to good measurements, the two parts fit together when united despite being built in separate locations. You can checkout more pictures on his Instagram.

If you want some more bike hacks, check out this Open Source Bike Computer or this Exercise Bike Game Controller.

Continue reading “SLS AMG Velomobile” →