Hackaday Podcast 154: A Good Enough CNC, Stepper Motors Unrolled, Smart Two-Wire LEDs, A Volcano Heard Around The World

February 4, 2022 by Tom Nardi 1 Comment

Join Hackaday Editor-in-Chief Elliot Williams and Staff Writer Dan Maloney for this week’s podcast as we talk about Elliot’s “defection” to another podcast, the pros and cons of CNC builds, and making Nixie clocks better with more clicking. We’ll explore how citizen scientists are keeping a finger on the pulse of planet Earth, watch a 2D stepper go through its paces, and figure out how a minimalist addressable LED strip works. From solving a Rubik’s cube to answering the age-old question, “Does a watched pot boil?” — spoiler alert: if it’s well designed, yes — this episode has something for everyone.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct Download (Less than 60 MB)

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Will A Kettle Filled With Alcohol Boil Dry?

February 1, 2022 by Lewin Day 31 Comments

The average home kettle is set up to switch off automatically when water reaches its boiling point. But would a kettle filled with alcohol, which has a significantly lower boiling point, actually turn off? [Steve Mould] set out to find out.

The prediction was that a kettle full of 40% strength vodka would boil dry, as the vodka would evaporate before it actually got to a hot enough temperature to cause the kettle’s cutout mechanism to kick in. The experiment was done outside to minimise the dangers from the ethanol vapor. As it turns out, the vapor from the boiling vodka is about 80% ethanol and just 20% water, so eventually the mixture left in the kettle is mostly water and it boils hot enough to trigger the cutout mechanism.

However, the experiment doesn’t end there. Trying again with 99% ethanol, when the fluid started boiling, the kettle switched off even more quickly. So what’s going on?

The kettle in question uses a bimetallic strip, which trips the switch off in the base of the kettle when it gets too hot. There’s also a tube inside the kettle that carries vapor from the internal cavity and lets it pass over the bimetallic strip. When the liquid inside the kettle boils, it forces hot vapor through the tube, out of the kettle and over the bimetallic strip.

This strip triggers at a temperature significantly lower than the boiling point of water; indeed, as long as the liquid in the kettle is fairly hot and is boiling enough to force vapor out the tube, the kettle will switch off. [Steve] points out that it’s a good mechanism, as this mechanism allows the kettle to respond to boiling itself, rather than the arbitrary 100 C point which water technically only boils at when one is at sea level.

It’s an interesting look at a safety system baked into something many of us use every day without even thinking. It’s not the first time we’ve seen [Steve] dive deep into the world of tea-making apparatus, either. Video after the break.

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Detail of an LED display made using ping-pong balls

Modular Design Enables Huge Ping-Pong Ball LED Displays

January 4, 2022 by Robin Kearey 22 Comments

Ping-pong balls have many uses: apart from playing table tennis, they have been used for countless art projects, science experiments, and even to raise ships from the bottom of the ocean. As it turns out, they also come in handy as diffusers for LED pixels, allowing the construction of large-size displays without requiring large individual LEDs.

[david] designed an LED ping-pong ball display using 3D printed components, which allows for the construction of arbitrarily-large LED displays thanks to a strictly modular design. The basic unit is a small piece that holds a single LED module and has a cup-like structure for attaching a standard table tennis ball. Twenty-five of these basic units combine together into a panel that also contains wiring ducts. Finally, any number of these panels can be combined into a display, thanks to clips that give the structure rigidity in the out-of-plane direction.

A 3D-printed frame for making an LED display — A single panel holds 25 LEDs and comes with cable ducts. On the right is a clip for connecting multiple frames together.

Of course, simply mounting LED modules is not enough to create a display: the LEDs also need to be connected to power and data lines. [david] didn’t relish the thought of having to cut and strip 1,800 pieces of wire, and therefore devised a clever way of automating this process: he put a bunch of wires onto a piece of card stock and used a laser cutter to burn off the insulation at regular intervals. Then it was simply a matter of soldering these wires onto the LEDs and snipping off pieces along the data bus.

The finished panel is driven by a combination of a Teensy 3.2 to generate the data signals and a Raspberry Pi to process the images. You can see the rather impressive result in the video embedded below; if this inspires you to build your own, you’ll be happy to hear that the STL files and all code are available on [david]’s project page.

Massive LED displays are always fun to watch, and although this is not the first one to use ping-pong balls as diffusers, its modularity and open-source design makes this one perhaps the easiest to replicate. Assuming you have a good supplier of ping-pong balls, of course.

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Salvaging Working LEDs From “Dead” Light Bulbs

September 14, 2021 by Tom Nardi 22 Comments

Sure the box said they would last for years or even decades, but anyone who’s picked up some bargain LED bulbs knows the reality is a bit more complicated. Sometimes a few LEDs in the array pop, reducing the overall light output. More commonly, the power supply starts to fail and the bulb begins to flicker or hum. In either event, you end up pulling the bulb and replacing it.

But [Bifferos] thinks we can do a bit better than that. Rather than just chalking it up to poor QA and tossing the bulb, why not do a little exploratory surgery to identify salvageable LEDs in an otherwise “dead” bulb? After pulling apart a couple of burned out bulbs (name brand and otherwise), he was able to pull out an impressive number of handy LED panels that could be easily repurposed. Naturally, with a little more coaxing, the individual SMD LEDs could be liberated and pushed into service as well.

Separate PCBs with banks of LEDs are ideal for reuse.

As you might expect, there are far too many different LED bulbs out there to create a comprehensive teardown guide, but [Bifferos] does provide some tricks to help get the bulb open without hurting yourself or destroying the thing in the process. Once inside, the design of the bulb will dictate what happens next. Bulbs with multiple arrays of LEDs on their own PCBs can be easily broken down, but if there’s just the single board, you may want to pull the LEDs off individually. To that end, the write-up demonstrates efficient methods of stripping the LEDs using either hot air or a pair of soldering irons.

We’ve talked previously about the rather underwhelming performance of modern LED bulbs compared to the manufacturer’s lofty claims. We’d rather see these bulbs designed well enough that they actually live up to their full potential, but the ability to salvage useful components from the failed luminaries at least softens the blow of having to toss them early. Though that’s not the only reason you should disassemble your LED bulbs before you put them in the trash.

Interactive LED Shoes That Anyone Can Build!

September 5, 2021 by Lewin Day 3 Comments

Normally when we see blinky projects these days, it’s using addressable LED strips with WS2812Bs, or similar alternatives. However, old-school blobby round LEDs are still on the market, and can still be put to great use. These DIY LED shoes from [TechnoChic] are an excellent example of just that.

The shoes use big 10mm LEDs that have color-changing smarts baked in. Simply power them up and they’ll fade between a series of colors. They’re run from a coin cell sewn on to the side of each shoe, with the LEDs jammed into the rear of the sole. A conductive product called Maker Tape is then used to create a circuit for the LEDs and the coin cell, along with a pressure switch inside each shoe. When the wearer puts weight on their heel, the switch conducts, lighting up the LEDs as the wearer takes each step.

This isn’t the first time we’ve seen a pair of shoes bedazzled with LEDs, but it’s arguably the easiest version of the concept to grace these pages. This is a quick way to create interactive flashing LED gadgets, and a great way for beginner makers to jazz up their projects.

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Small sensor built into audio jack, held in tweezers

Measuring LED Flicker, With Phototransistor And Audio App

September 1, 2021 by Donald Papp 26 Comments

No one likes a flickering light source, but lighting is often dependent on the quality of a building’s main AC power. Light intensity has a close relation to the supply voltage, but bulb type plays a role as well. Incandescent and fluorescent bulbs do not instantly cease emitting the instant power is removed, allowing their output to “coast” somewhat to mask power supply inconsistencies, but LED bulbs can be a different story. LED light output has very little inertia to it, and the quality of both the main AC supply and the bulb’s AC rectifier and filtering will play a big role in the stability of an LED bulb’s output.

Mobile phone spectrum analyzer pointed at light source — The DIY photosensor takes the place of the microphone input.

[Tweepy] wanted to measure and quantify this effect, and found a way to do so with an NPN phototransistor, a resistor, and a 3.5 mm audio plug. The phototransistor and resistor take the place of a microphone plugged into the audio jack of an Android mobile phone, which is running an audio oscilloscope and spectrum analyzer app. The app is meant to work with an audio signal, but it works just as well with [Tweepy]’s DIY photosensor.

Results are simple to interpret; the smoother and fewer the peaks, the better. [Tweepy] did some testing with different lighting solutions and found that the best performer was, perhaps unsurprisingly, a lighting panel intended for photography. The worst performer was an ultra-cheap LED bulb. Not bad for a simple DIY sensor and an existing mobile phone app intended for audio.

Want a closer look at what goes into different LED bulbs and how they tick? We have you covered. Not all LED bulbs are the same, either. Some are stripped to the bone and others are stuffed with unexpected goodness.

This Week In Security: John Deere, ProxyLogin Detailed, And Pneumatic Tubes

August 13, 2021 by Jonathan Bennett 14 Comments

We’ve covered the right-to-repair saga, and one of the companies that have become rather notorious is John Deere. The other side to the poorly managed interconnected mess is security issues. There’s a certain irony to how this story started: Somebody noticed that John Deere equipment didn’t have any CVEs at all. A normal person might think that this must mean their products are super secure, but a security researcher knows that something more interesting is afoot. Our old friends [Sick Codes], [John Jackson], and a host of others saw this as a sure sign that there were plenty of vulnerabilities to be found, and it seems they were correct.

Vulnerabilities included a handful of cross-site scripting attacks, an authentication bypass via request smuggling, misconfigured security, SQL injections, RCEs and more. Put together, these vulnerabilities allowed for full control of the John Deere system, including the ability to manipulate all the equipment connected to the system.

During the Defcon presentation, linked below, [Sick Codes] recalled the moment when they realized they were working on an important problem. Rather than complain about not getting paid for the vulnerabilities found, a contributor simply noted that he valued having food to eat. A coordinated attack on JD equipment could cause big problems for a bunch of farms across a country.

They ended up contacting CISA, due to a lack of serious response from the vendors. CISA took the threat seriously, and the problems starting getting fixed. This isn’t a problem limited to one company. Case had similar issues that have also been fixed, and it was implied that other vendors have similar problems that are still in the process of being addressed. Continue reading “This Week In Security: John Deere, ProxyLogin Detailed, And Pneumatic Tubes” →