classic hacks

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Quick And Dirty MIDI Interface With USBASP

November 4, 2018 by 11 Comments

[Robson Couto] recently found himself in need of MIDI interface for a project he was working on, but didn’t want to buy one just to use it once; we’ve all been there. Being the creative fellow that he is, he decided to come up with something that not only used the parts he had on-hand but could be completed in one afternoon. Truly a hacker after our own hearts.

Searching around online, he found documentation for using an ATtiny microcontroller as a MIDI interface using V-USB. He figured it shouldn’t be too difficult to adapt that project to run on one of the many USBASP programmers he had laying around, and got to work updating the code.

Originally written for the ATtiny2313, [Robson] first had to change around the pin configuration so it would work on the ATmega8 in the USBASP, and also updated the USB-V implementation to the latest version. With the code updated, he programmed one of the USBASP adapters with a second one by connecting them together and putting a jumper on the J2 header.

He had the software sorted, but there was still a bit of hardware work to do. To provide isolation for the MIDI device, he put together a small circuit utilizing a 6N137 optoisolator and a couple of passive components on a piece of perf board. It’s not pretty, but it does fit right into the programming connector on the USBASP. He could have fired up his PCB CNC but thought it was a bit overkill for such a simple board.

[Robson] notes that he hasn’t implemented MIDI output with his adapter, but that the code and the chip are perfectly capable of it if you need it for your project. Finding the schematic to hook up to the programmer’s TX pin is left as an exercise for the reader.

If you don’t have a USBASP in the parts bin, we’ve seen a very similar trick done with an Arduino clone in the past.

Eight Player GameCube Adapter Is Ready For Smash

November 2, 2018 by 4 Comments

With the release of Smash Ultimate fast approaching for the Nintendo Switch, [Patrick Hess] wanted to get ahead of the game and make sure his squad had the equipment they’d need. Namely, support for the GameCube controllers that serious Smash Bros players demand. But it wasn’t enough to have one or two of them hooked up, or even four. Not even six GameCube controllers could satiate his desire. No, he needed to have support for eight simultaneous GameCube controllers, and he wanted to look good doing it too.

Enter his meticulously designed eight player GameCube to USB adapter. Made out of dual official Nintendo GameCube to USB adapters (intended for the Wii U) merged together in a 3D printed case, the final result looks like something that could earn the coveted Nintendo Seal of Approval. Or at least, something that might pop up on the import sites in the next month or two for a few bucks.

[Patrick] started the project by recreating the official adapter PCBs and their housings in 3D using a pair of calipers. After a couple of test prints to make sure he had all the dimensions right, he could then move on to designing his final enclosure knowing he had accurate data to model around.

In addition to the two adapter boards, there’s also a four port USB hub inside the device’s case. Each adapter has two USB leads, here shortened to fit inside the case, which connect up to the hub. The integrated hub allows connecting all eight GameCube controllers through only a single USB connection. All controllers worked as expected during intense testing on the Wii U’s version of Smash Bros, though at this point [Patrick] can only assume it will work when the Switch version is released.

If there’s a downside to this project, it’s that the design for the 3D printed case is so intricate that [Patrick] was only able to print it on a machine that supported water-soluble PVA supports. A somewhat tall order for the average hacker; it would be interesting to see if somebody could make a second pass on the enclosure that is geared more towards printability than aesthetics.

While the design of the GameCube controller remains somewhat controversial after all these years, there’s no denying it retains an impressive following. Whether turning them into USB devices, shrinking them to preposterously small dimensions, or just finding increasingly creative ways to use them on Nintendo’s latest console, hackers are definitely in love with the gonzo little controller that’s now pushing 20 years old.

7 Segment Clockwork Display Made From Cardboard

October 31, 2018 by 25 Comments

We’ve seen a variety of oddball 7-segment displays in the past, but this one uses a new material: both for the display and the mechanical mechanism that drives it; cardboard. Yup, the whole thing is made from cardboard, wood and a few rubber bands. [The Q] shows how he put together in this nice video, starting from first principles that show how the segments are made: simple pieces of cardboard painted on one side with fluorescent paint. A piece of wood pushes the element out to blank it, and each element is connected to a cam wheel that pushes the wood in or out.

The really clever bit is that [The Q] mapped digits 0 – 9 onto a matrix for which of the 7 segments is “on” or “off”. He then used this information to create a stack of 7 cams on a central axle. As you rotate the axle, the cams turn, moving the wooding arms. The arms then cause the elements to flip as they count up through the digits. In essence, he engineered a physical decimal to 7 segment decoder, much like the electronic one inside the SN74LS47. The whole assembly is capped by a knob that indicates which digit is currently displayed. If mechanical displays like this are your thing, check out this one made from LEGO parts, or this awesome 3D printed creation.

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Child’s Pushcar Gets Serious Horsepower

October 26, 2018 by 10 Comments

A pushcar is a great toy for a young child. They’re great excercise, and kids love anything on wheels. However, the bigger kids might want something with a little more grunt. [Master Milo] has just the thing – an engine from a concrete saw and the fabrication skills to match. (YouTube, embedded below.)

The build starts with the disassembly of the concrete saw, with covers, the saw drive and handle all removed. This leaves a 70 cc petrol engine with a centrifugal clutch already fitted. A steel frame is then built around the engine to mount the rest of the drivetrain. An intermediate shaft is used at the rear to allow for an extra level of gear reduction, and steering up front is handled with parts cribbed from an old ATV. The plastic shell of the pushcar is then fitted over the top and a seat constructed out of scrap wood.

Mechanical parts are in ready supply, with bearings and shafts all sourced from INDI, a European equivalent to McMaster Carr. By purchasing gears, belts and other parts off the shelf, it’s easy to make something that fits first time with a minimum of modification required.

The testing video is worth a watch – with both top speed and handling tests. The platform’s handling does leave something to be desired, but that’s half the fun in a build like this.

We’re no strangers to these projects around these parts – a modded Power Wheels is a great electric take on the same concept. Continue reading “Child’s Pushcar Gets Serious Horsepower” →

DIY Tuning Capacitors From Washers And 3D-Printed Parts

October 25, 2018 by 34 Comments

The inside of classic radios holds wonders that the sterile chips and SMD components of today’s circuits can’t hold a candle to. Chunky resistors and capacitors, vacuum tubes with cathodes aglow, and seemingly free-form loops of wire forming inductors will all likely make an appearance. But the most fascinating bit of any old radio was connected to the tuning knob: the big variable capacitor with its interdigitating metal plates. Watching one at work, with its plates evenly and finely spaced, is still a joy to behold.

In an attempt to recapture a little of that magic, [Jeremy S. Cook] came up with this home-brew variable tuning capacitor. The frame is built mainly from 3D-printed parts, which supports a shaft made from a common bolt. Plates are fashioned from stainless steel fender washers cut in half; the fixed plates are press-fit into the frame while the rotary plates ride on the shaft. The spacing between the rotary plates is maintained by printed spacers, which also serve to lock the rotor into one solid unit. [Jeremy]’s prototype, for which he provides STL files, can be tuned between about 7 and 15 pF. Check out the build in the video below.

We love the look of this, and we can imagine custom tuning caps would come in handy for certain retro radio builds. The tuning range is a little narrow, but that could be fixed with more plates or closer spacing. That might be a tall order with thick steel washers, but we’ve seen really thin aluminum machined and closely spaced before, so this might be one approach to higher capacitance. Continue reading “DIY Tuning Capacitors From Washers And 3D-Printed Parts” →

Camera Obscura On Wheels Hits The Open Road

October 24, 2018 by 19 Comments

A camera obscura is a very simple device. Consisting of a dark chamber, with only a pinhole to let light in, it focuses an image on its inside surface. If you want to take a permanent copy, it’s as simple as installing a photosensitive film inside and managing the exposure time. Sounds like a normal camera, right? The difference is the scale —  a camera obscura is large enough that humans can stand inside and view the image. Usually, they are large stationary rooms. [Physics Girl] took the show on the road by building a camera obscura out of a rented box truck.

The optics of the camera obscura project an image upside-down.

The basic concept is a great one – hire a box truck, and cover the rear opening with cardboard. Cut a small hole in the cardboard, and you’ve created a camera obscura on wheels. The video does a great job of explaining the optical principles behind what’s happening, and there’s even experimentation around how to change the exposure level and focus through modification of the aperture.

The only downside to viewing a camera obscura on video is that you can’t appreciate the resolution and detail visible in real life. Trust us though, it’s better than any HDTV on the market today.

The rolling camera obscura makes for a great experiment which requires little more than some cardboard, tape, and a sunny day. It would be great fun to execute as an educational activity at a school or makerspace. Once you’ve tackled that, perhaps consider the digital version. Video after the break.

[Thanks to Baldpower for the tip!]

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