Misc Hacks

4173 Articles

Magnets And Printed Parts Make Quick-Disconnect Terminals

November 15, 2018 by 19 Comments

The Apple MagSafe power connector is long gone from their product line, but that doesn’t mean that magnetic connectors aren’t without their charms. It just takes the right application, and finding one might be easier with these homebrew magnetic connectors.

We’ll admit that the application that [Wesley Lee] found for his magnetic connectors is perhaps a little odd. He’s building something called Linobyte, a hybrid art and electronics project that pays homage to computing history with very high-style, interactive core memory modules. The connectors are for the sense wire that is weaved through the eight toroids on each module, to program it with a single byte. Each connector has a 3D-printed boot that holds a small, gold-plated neodymium magnet with the sense wire soldered to it. A socket holds another magnet to the underside of a PCB. The magnet in the boot sticks to the PCB and makes contact with pads, completing the circuit. We know what you’re thinking: heating a magnet past the Curie point is a great way to ruin it. [Wesley] admits that happens, but it just makes the connection a little weaker, which works for his application. The short video below shows how he puts them together.

We can think of a couple of ways these connectors would be useful, and we really like the look of the whole project. It’ll be interesting to see where it goes, but in the meantime, brushing up on how magnets work could be fun. Continue reading “Magnets And Printed Parts Make Quick-Disconnect Terminals” →

What’s The Difference? Ask An Op Amp

November 13, 2018 by 12 Comments

If you’ve ever wondered why an op amp has the little plus and minus symbols on it, its because at the heart of it, the device is a differential amplifier. The problem is that — ideally, at least — it has infinite gain so it works like a comparator and that’s not what you usually want. So we put resistors around the thing to constrain it and get useful amplification out of it. [Stephen Mendes] does the analysis for you about how the standard configuration for a differential amplifier works. He assumes you know the stock formulae for the inverting and non-inverting amplifier configurations and uses superposition.

[Stephen] mentions that’s the easiest way to do it and then goes on to do it sort of how we would do it as a check. We think that’s the easier method, but maybe its a matter of preference. Either way, you get the right answer.

Continue reading “What’s The Difference? Ask An Op Amp” →

A Fleet Of Pressure Washers Powers This Interactive Public Fountain

November 11, 2018 by 15 Comments

Public art installations can be cool. Adding in audience interactivity bumps up the coolness factor a bit. Throw civic pride, dancing jets of water, music, and lights into the project, and you get this very cool pressure washer powered musical fountain.

The exhibit that [Niklas Roy] came up with is called Wasserorgel, or “water organ”, an apt name for the creation. Built as part of a celebration of industry in Germany, the display was built in the small town of Winnenden, home to Kärcher, a cleaning equipment company best known for their line of pressure washers in the distinctive yellow cases. Eight of the company’s electric pressure washers were featured in the Wasserorgel, which shot streams of water and played notes in response to passersby tickling the sturdy and waterproof 3D-printed keyboard. The show was managed by an Arduino with a MIDI shield, which controlled the pressure washers via solid state relays and even accepted input from an anemometer to shut down the show if it got too windy, lest the nearby [Frau Dimitrakudi] be dampened.

The video below shows how engaging the Wasserorgel was during its weeks-long run in the town market square; there’s also one in German with build details. And while we can’t recall seeing pressure washers in public art before, we do remember one being used as the basis of a DIY water-jet cutter.

Continue reading “A Fleet Of Pressure Washers Powers This Interactive Public Fountain” →

Rewound And Rewired BLDC Makes A Half-Decent Generator

November 8, 2018 by 18 Comments

What’s the best way to turn a high-powered brushless DC motor optimized for hobby use into a decent low-RPM generator? Do you take a purely mechanical approach and slap a gearbox on the shaft? Or do you tackle the problem electrically?

The latter approach is what [GreatScott!] settled on with his BLDC rewinding and rewiring project. Having previously explored which motors have the best potential as generators, he knew the essential problem: in rough terms, hobby BLDCs are optimized for turning volts into RPMs, and not the other way around. He started with a teardown of a small motor, to understand the mechanical challenges involved, then moved onto a larger motor. The bigger motor was stubborn, but with some elbow grease, a lot of scratches, and some destroyed bearings, the motor was relieved of both its rotor and stator. The windings were stripped off and replaced with heavier magnet wire with more turns per pole than the original. The effect of this was to drive the Kv down and allow better performance at low RPMs. Things looked even better when the windings were rewired from delta to wye configuration.

The take-home lesson is probably to use a generator where you need a generator and let motors be motors. But we appreciate [GreatScott!]’s lesson on the innards of BLDCs nonetheless, and his other work in the “DIY or buy?” vein. Whether you want to make your own inverter, turn a hard drive motor into an encoder, or roll your own lithium battery pack, he’s done a lot of the dirty work already.

Continue reading “Rewound And Rewired BLDC Makes A Half-Decent Generator” →

Pint-sized Jacob’s Ladder Packs 10,000 Volts In A Pickle Jar

November 5, 2018 by 12 Comments

File this one away for your mad scientist costume next Halloween: [bitluni]’s Pocket Jacob’s Ladder is the perfect high voltage accessory for those folks with five dollars in parts, a 3D printer, and very big pockets.

[bitluni]’s video shows you all the parts you’ll need and guides you through the very simple build process. For parts, you’ll require a cheap and readily-available high-voltage transformer, a battery holder, some silver wire for the conductors, and a few other minor bits like solder and a power switch.

Once the electronics are soldered together, they’re stuffed inside a 3d printed case that [bitluni] designed with FreeCAD. The FreeCAD and STL files are all available on Thingiverse. We’re not sure what type of jar [bitluni] used to enclose the electrodes. If your jar isn’t a match, you’ll have to get familiar with FreeCAD or start from scratch with your favorite CAD package.

Either way, we enjoy the slight nod toward electrical safety and the reuse of household objects for project enclosures.

If you’re interested in a Jacob’s Ladder with significantly higher voltage we’ve got you covered, or we’ve also written about another tiny portable Jacob’s Ladder.

The full video is embedded after the break.

Continue reading “Pint-sized Jacob’s Ladder Packs 10,000 Volts In A Pickle Jar” →

Stepper Motor Mods Improve CNC Flat Coil Winder

November 4, 2018 by 56 Comments

Finding just the right off-the-shelf part to complete a project is a satisfying experience – buy it, bolt it on, get on with business. Things don’t always work out so easily, though, which often requires the even more satisfying experience of modifying an existing part to do the job. Modifying a stepper motor by drilling a hole down its shaft probably qualifies for the satisfying mod of the year award.

That’s what [Russ] did to make needed improvements to his CNC flat-coil winder, which uses a modified delta-style 3D-printer to roll fine magnet wire out onto adhesive paper to form beautiful coils of various sizes and shapes. [Russ] has been tweaking his design since we featured it and coming up with better and better coils. While experimenting, the passive roller at the business end proved to be a liability. The problem was that the contact point lagged behind the center axis of the delta, leading to problems with the G-code. [Russ] figured that a new tool with the contact point at the dead center would help. The downside would be having to actively swivel the tool in concert with the X- and Y-axis movements. The video below shows his mods, which include disassembling the NEMA-17 stepper and drilling out the shaft to pass the coil wire. [Russ] also spent some time reversing the rotor in the frame and provided a small preload spring to keep the coil roller in contact with the paper.

A real-time coil winding session starts at the 21:18 mark, and we’ve got to admit it’s oddly soothing to watch. We’re not sure exactly what [Russ] intends to do with these coils, and by his own admission, neither is he. But it’s still pretty cool to see, and the stepper motor mods are a neat trick to keep in mind.

Continue reading “Stepper Motor Mods Improve CNC Flat Coil Winder” →

Save A Few Steps On Your Next Build With These Easy Linear Actuators

November 2, 2018 by 18 Comments

A lot of projects require linear motion, but not all of them require high-accuracy linear slides and expensive ball screws. When just a little shove for a door or the ability to pop something up out of an enclosure is all you need, finding just the right actuator can be a chore.

Unless someone has done the work for you, of course. That’s what [Ali] from PotentPrintables did with these 3D-printed linear actuators. It’s a simple rack-and-pinion design that’s suitable for light loads and comes in two sizes, supporting both the 9-g micro servos and the larger, more powerful version. Each design has a pinion that has to be glued to a servo horn, and a selection of rack lengths to suit your needs. The printed parts are nothing fancy, but seem to have material in the right places to bear the loads these actuators will encounter. [Ali] has included parts lists and build instructions in with the STL files, as well as sample Arduino code to get you started. The video below shows the actuators in action.

We’re heartened to learn that [Ali] was at least partly inspired to undertake this design by a previous Hackaday post. And we’re glad he decided to share his version; it might save us a few steps on our next build.

Continue reading “Save A Few Steps On Your Next Build With These Easy Linear Actuators” →