Printing Yoda Heads: Re-Makers Riffing!

February 27, 2021 by 50 Comments

We had a comment recently from a nasty little troll (gasp! on the Internet!). The claim was that most makers are really just “copiers” because they’re not doing original work, whatever that would mean, but instead just re-making projects that other people have already done. People who print other peoples’ 3D models, or use other peoples’ hardware or software modules are necessarily not being creative. Debunking a cheap troll isn’t enough because, on deeper reflection, I’m guilty of the same generic sentiment; that feeling that copying other people’s work isn’t as worthy as making your own. And I think that’s wrong!

In the 3D printing world in particular, I’m guilty of dismissively classifying projects as “Yoda Heads”. About ten years ago, [chylld] uploaded a clean, high-res model of Yoda to Thingiverse, and everyone printed it out. Heck, my wife still has hers on her desk; and alone this is proof that straight-up copying has worth, because it made a sweet little gift. After a while, Yoda gave way to Baby Groots, and strangely enough we’re back to Yoda again, but it’s Baby Yoda now. Continue reading “Printing Yoda Heads: Re-Makers Riffing!” →

A Very Modern Tube Headphone Amplifier

February 27, 2021 by 34 Comments

Once a discarded relic, over the years the humble vacuum tube has been rehabilitated in the arena of specialist audio. There are plenty of tube amplifiers now being manufactured, with a popular choice being headphone amplifiers that use a tube as a gain stage followed by an op-amp as a buffer with a low impedance output. This forms the basis of [Ratti3]’s amplifier, but with the added interest of a battery supply and a Bluetooth connection.

The tube circuit is a very conventional anode follower using an EF95 pentode. This provides plenty of gain and of course that “valve sound” beloved of audio enthusiasts, but suffers from an output impedance too high to drive a set of headphones. An NE5532 steps in for the op-amp buffer role, making for a very simple circuit. Power comes from a set of four 18650 Lithium-Ion cells with associated charger and balance boards, while a little switching boost converter provides the 100 volt HT for the tubes.

We’ve visited this type of amplifier before with a similar but much more rough-around-the-edges Chinese version. That had some astonishingly cheap Chinese tubes, but if we’re seeking better components it’s interesting to know just who makes tubes these days.

Sounding The Humble LED

February 27, 2021 by 22 Comments

Here at Hackaday we’re no strangers to the colorful glow of LEDs. But what if there was more to appreciate beneath the surface? Back in 2011 [Windell] over at Evil Mad Scientist dug into a certain variety of LED and discovered they had a song to sing.

Over the last couple decades, you’ve likely encountered the flickering “candle flame” variety of LED. Often found embedded in small plastic candle simulacra they are shaped like typical through hole “gumdrop” style LEDs, but pack some extra magic which causes them to flicker erratically. Coupled with a warm white color temperature the effect isn’t entirely dissimilar to the flickering of a candle flame.

To the Hackaday reader (and [Windell]) the cause of the flickering may be fairly clear, there is an IC embedded in the lens of the LED. See photo at top for an example of how this might look, helpfully magnified by the lens of the LED itself. Looking through the lens the captive die is visible, as well as the bond wires connecting it to the legs and light emitting diode itself. [Windell]’s observation is that together this assembly makes for a somewhat strange electrical component; from the perspective of the circuit it appears to randomly vary the current flowing through the LED.

He includes two interesting demos. One is that by attaching the flickering LED to a BJT he can turn it into a current amplifier and successfully drive a much more powerful 1W LED with the same effect. The other is that  with the power of the amplifier the same flickering LED can drive a buzzer as well. The effect is surprisingly pleasant, though we’d hesitate to call it musical.

For a more recent example of a similar phenomenon with a very different sound, check out out [Emily Velasco]’s playback of a similarly constructed RGB color changing LED, embedded below. We’ve seen optical tools used to decode LED flickers into data streams, but not for audio playback! We have also covered some LED flicker reverse engineering that spills more of the mystery sealed up in these specialized diodes.

Continue reading “Sounding The Humble LED” →

Bottle Filler Perfectly Tops Your Cup

February 26, 2021 by 23 Comments

You know those bottle fillers at schools and airports? What if you had one of those at home?

We know what you’re going to say: “My fridge has one of those!” Well ours doesn’t, and even though [Chris Courses’] fridge did, his bottle of choice didn’t fit in the vertically-challenged water and ice hutch, nor did it fill autonomously. The solution was to build a dubiously placed, but nonetheless awesome custom bottle filler in his kitchen.

The plumbing for the project couldn’t be more straight-forward: a 5-year undersink water filter, electronically actuated valve, some tubing, and a T to splice into the existing water line going to the fridge. Where the rubber hits the road is making this look nice. [Chris] spends a lot of time printing face plates, pouring resin as a diffuser, and post processing. After failing on one formulation of resin, the second achieves a nice look, and the unit is heavily sanded, filled, painted, prayed over, and given the green light for installation.

For the electronics [Chris] went for a Raspberry Pi to monitor four buttons and dispense a precise allotment tailored to each of his favorite drinking vessels. While the dispenser is at work, three rows of LEDs play an animated pattern. Where we begin to scratch our heads is the demo below which shows there is no drain or drip tray below the dispenser — seems like an accident waiting to happen.

Our remaining questions are about automating the top-off process. At first blush you might wonder why a sensor wasn’t included to shut off the filler automatically. But how would that work? The dispenser needs to establish the height of the bottle and that’s a non-trivial task, perhaps best accomplished with computer vision or a CCD line sensor. How would you do it? Continue reading “Bottle Filler Perfectly Tops Your Cup” →

The Famous Basic Computer Games Book Gets A 2021 Update

February 26, 2021 by 53 Comments

If you are a certain age, your first programming language was almost certainly BASIC. You probably at least saw the famous book by Ahl, titled BASIC Computer Games or 101 BASIC Computer Games. The book, published in 1973 by [David Ahl] was a staple in its day and the first computer book to sell over one million copies. Of course, if you want to run Super Star Trek or Hamurabi, you better fire up an old retrocomputer or a simulator because BASIC in 1973 doesn’t look like what we have today. Or, you can head to GitHub where [coding-horror] is inviting people to help update the programs using modern languages.

One of our favorites, Bagels, is there with directories for C#, Java, Javascript, Python, Ruby, and VB.net. It doesn’t appear that all of the games are in all the languages, though. There’s also a .Net solution file that apparently has a few entries in it. We were also happy to see Super Star Trek represented, along with a link to an article about a C++ language port. The original games were tweaked to run on VintageBasic.

Continue reading “The Famous Basic Computer Games Book Gets A 2021 Update” →

3D Printed Printing Press Turns You Into Gutenberg

February 26, 2021 by 14 Comments

A few machines have truly changed the world, such as the wheel, steam engines, or the printing press. Maybe 3D printers will be on that list one day too. But for today, you can use your 3D printer to produce a working printing press by following plans from [Ian Mackay]. The machine, Hi-Bred, allows you to place printed blocks in a chase — that’s the technical term — run a brayer laden with ink over the type blocks and hand press a piece of paper with the platen.

The idea is more or less like a giant rubber stamp. As [Ian] points out, one way to think about it is that white pixels are 0mm high and black pixels are 3mm high. He suggests looking at old woodcuts for inspiration.

Continue reading “3D Printed Printing Press Turns You Into Gutenberg” →

Spectrogram Drawing For Fun And Coding

February 26, 2021 by 17 Comments

It probably can’t have taken long after the first spectrum waterfall display was created, before somebody had a go at creating a waveform that would create an image in the waterfall. We don’t know who that pioneer was, but it’s over 20 years since Aphex Twin famously used the technique in their music, so it’s nothing new. If you fancy a go for yourself, [Gokberk Yaltirakli] has the project for you, creating waterfall images with an SDR from image files, using a bit of Python code.

The value here isn’t necessarily in creating the waterfall of Bitcoin logos that can be seen in the video he’s put on the page, instead it’s in the simple explanation of creating I and Q values for an SDR. The code is a bit slow so writes its values to a file which is output by a HackRF, but it could just as easily be used by any other capable output device such as GNU Radio and a soundcard if you too want an Aphex Twin moment. The hardware for displaying a spectrum waterfall doesn’t even have to be very complex.

Thanks [Leo] for the tip.