It’s A TV-Scope-Guitar Amplifier!

October 26, 2019 by Jenny List 8 Comments

Guitar amplifiers are a frequent project, and despite being little more than a simple audio amplifier on paper, they conceal a surprising quantity of variables in search of a particular sound. We’ve seen a lot of them, but never one quite like [Nate Croson]’s CRT TV guitar amplifier. The LM386 doesn’t just drive the speaker, he’s also using it to turn the TV into a crude oscilloscope to form a visualisation of the sound.

The video showing this feat is below the break, and it puts us in a quandary due to being short on technical information. He’s driving the horizontal coils with the TV’s 50 Hz sawtooth field timebase, and the vertical ones with the audio from the LM386. We aren’t sure whether he’s rotated the yoke or whether the connections have been swapped, but the result is certainly impressive.

So given that there’s not quite as much technical detail as we’d like, why has this project captured our interest? Because it serves as a reminder that a CRT TV is a bit more than a useless anachronism, it’s a complex analogue device with significant and unique hacking potential. The older ones in particular provide endless possibilities for modification and circuit bending, and make for a fascinating analogue playground at a very agreeable price. It’s worth pointing out however that some of the voltages involved can make them a hazardous prospect for the unwary hacker. If you’re interested though, take a look at our dive into an older model.

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Pelican Case Becomes Thumping Bluetooth Speaker

October 25, 2019 by Lewin Day 5 Comments

Pelican cases are great if you need a rugged enclosure to protect some sensitive gear. They’re also highly moddable, and can make a great base for a Bluetooth speaker build.

Like many modern builds, this is very much a case of wiring together a series of off-the-shelf modules into a larger whole. A Tinyshine Bluetooth audio board is hooked up to a Dayton Audio Class D amplifier. Class D amplifiers are a great choice for any portable audio application for their compact size and good power efficiency. Power is supplied by a hand-built 3-cell 18650 pack, while a standard buck converter and battery protection board are subbed in to make sure the batteries stay happy.

Not wanting to skimp on audio quality, a pair of Dayton Audio full-range drivers are installed, negating the need for a crossover install, or multiple drivers per channel. There’s a third passive driver on the back side as well, though we’re not 100% clear on its purpose. If you’re clued in, let us know in the comments.

It’s a project that serves as a great blueprint for anyone wanting to build their own high-fidelity Bluetooth speaker. The relevant modules are all readily available – it’s just a case of hooking them up to a nice amp and a decent set of speakers. The design is all up to you – whether you go for a pipe, a bag, or something altogether entirely. Happy hacking!

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Build This Handy Leak Detector For $1.02

October 23, 2019 by Tom Nardi 23 Comments

You’ve probably noticed that modern life has become rather complicated, and the projects we cover here on Hackaday have not been immune to the march of progress. We certainly aren’t complaining, but we’ll admit to the occasional wistful daydream of returning to the days when the front page of Hackaday looked more MacGyver than Microsoft.

Which is precisely why this hacked together water alarm from [dB] is so appealing. Dubbed the “SqueakyLeaks”, this gadget started its life as a simple wireless intruder alarm from the Dollar Tree. When the magnet got far enough from the battery-powered base, a 90 dB warble would kick in and let you know somebody had opened a window or a door they shouldn’t have.

But with a little rewiring and two Canadian pennies serving as contacts, the alarm has been converted to a water detector that can be placed around potential leaky appliances like the water heater or in areas where you want to be alerted to water accumulation such as sumps. They’re basically “set and forget”, as [dB] says the three LR44 batteries used in the alarms should last about two years. Though with a BOM of $1.02 CAD, it’s probably cheaper to just make multiples and throw them out when the batteries die. Continue reading “Build This Handy Leak Detector For $1.02” →

Next Level Spirit Level Is On The Level

October 18, 2019 by Kristina Panos 10 Comments

Miss your shot and scratch on the eight ball? It’s natural to blame the table for not being level so you can save face, but in all likelihood, you’re probably right. [Huygens Optics]’s father never misses a billiards shot on his home table, until one day he did. [Huygens Optics] rushed to his aid and built an extremely precise spirit level for the table so it will never happen again.

First and foremost, he had to decide how sensitive the spirit level should be. Obviously, the table should be as level as possible, though other factors like the condition of the felt will come into play as well. In doing some calculations, he found that every degree of leveling error in the table translates to several millimeters of ball unevenness and deviation, so he wanted the level to have .01 degrees of accuracy. How he manages this feat of grinding and polishing in a hobbyist workshop is all captured in the fascinating video after the break.

The level is made from two disks cut from leftover 15mm borosilicate glass. Between the disks is a 4mm cavity for the liquid (ethyl alcohol) and the air bubble to move around. To avoid introducing error with uneven adhesive application, [Huygens Optics] tried to join the disks using optical contact bonding, wherein two surfaces stick together through the magic of intermolecular forces, like the one that keeps geckos attached to vertical things. That worked quite well until he added the liquid, which broke the bond. Instead, he used a thin, UV-curable epoxy.

Getting into optics doesn’t have to cost a lot. Instead of buying or grinding lenses for experimentation, you can laser-cut lens profiles out of acrylic.

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This Dibbling Plate Will Grow Your Love For Sowing

October 7, 2019 by Kristina Panos 13 Comments

One of the best things about 3D printers and laser cutters is their ability to produce specialized tools that steal time back from tedious processes. Seed sowing is a great example of this. Even if you only want to sow one tray with two dozen or so seeds, you still have to fill the tray with soil, level it off, compress it evenly, and poke all the holes. When seed sowing is the kernel of your bread and butter, doing all of that manually will eat up a lot of time.

There are machines out there to do dibbling on a large scale, but [Michael Ratcliffe] has been dabbling in dibbling plates for the smaller-scale farm. He’s created an all-in-one tool that does everything but dump the soil in the tray. Once you’ve done that, you can use edge to level off the excess soil, compress it with the back side, and then flip to the bed-of-nails side to make all the holes at once. It comes apart easily, so anyone can replace broken or dulled dibblers.

[Michael] is selling these fairly cheaply, but you can find all the files and build instructions out there in the Thingiverse. We planted the demo video after the break.

More into micro-greens? 3D printing can feed that fixation, too.

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A Bootable Greeting For The Xenomorph In Your Life

October 7, 2019 by Tom Nardi 4 Comments

When he needed a gift for his Alien superfan friend, [Stephen Brennan] decided the best way to put his unique set of skills to use would be to create a bootable Linux operating system that captures the sights and sounds of the Nostromo’s retro-futuristic computer systems. We could all use a friend like that.

Even if would never occur to you gift somebody a bootable flash drive, there’s a wealth of information in this blog post about Linux customization which could be useful for all sorts of projects. From creating a bootsplash image to automatically starting up a minimalistic windowing environment so a single graphical application takes center stage.

Whether you’re looking to tweak your desktop machine or build a Raspberry Pi kiosk, the commands and tips that [Stephen] shows off are sure to be interesting for anyone who’s not quite satisfied with how their Linux distribution of choice looks “out of the box”.

But there’s more to this project than a custom wallpaper and some retro fonts. [Stephen] actually took the time to create a facsimile of the “Personal Terminal” computer interface shown in the recent Alien: Isolation game in C using ncurses. The resulting program, aptly named “alien-console”, is released under the BSD license and is flexible enough that you could either use it as a base to build your own cyberpunk UI, or just load it up with custom text files and use it on your cyberdeck as-is.

Finally, to really sell the Alien feel, [Stephen] went through and ripped various audio clips from the film and wove them into the OS so it would make the movie-appropriate boops and beeps. He even included a track of the Nostromo’s ambient engine noise for proper immersion. But perhaps our favorite trick is the use of the sleep command to artificially slow down the terminal and give everything a bit more “weight”. After all, flying a pretend starship should feel like serious business.

No Need To Watch Your Tea, This Robot Does It For You

October 3, 2019 by Sharon Lin 15 Comments

For anyone who’s ever had to make their own tea, steeping it for the right amount of time can be a pain. That’s precisely the problem that the automatic tea brewing robot solves with its painless approach to brewing tea, built by Slovenian electrical engineering student [Kristjan Berce].

You can use the robot by setting a timer on the knob, at which point the robot raises it arm for the tea bag then dips in the water every 30 seconds until the time has passed. At the end of the timer, the bag is raised clear of the cup to end the brewing. It’s a remarkably simple design that almost evokes chindogu (the Japanese art of useless inventions) if not for the fact that the robot actually serves a useful purpose.

The components for 3D printing the robot are available online, consisting of a case, a container for the Arduino-powered electronics, the lever for holding the tea, and the gear that raises the lever up and down. The device also uses an integrated Li-Ion battery with an accessible charging port and integrated BMS. A 35BYJ46 stepper motor and ULN2003 driver are used to move the 3D printed mechanism. The device uses a potentiometer for setting the steeping time between 1 and 9 minutes, and there’s even a buzzer for indicating once the tea is done brewing.

The Gerber and Arduino code files are open-source for any hackers looking to make their own tea brewers; just take care they operate with “deadly punctuality”.

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