Practical Enclosure Design, Optimized for 3D Printing

[3D Hubs] have shared a handy guide on designing practical and 3D printing-friendly enclosures. The guide walks through the design of a two shell, two button remote control enclosure. It allows for a PCB mounted inside, exposes a USB port, and is optimized for 3D printing without painting itself into a corner in the process. [3D Hubs] uses Fusion 360 (free to hobbyists and startups) in their examples, but the design principles are easily implemented with any tool.

One of the tips is to design parts with wall thicknesses that are a multiple of the printer’s nozzle diameter. For example, a 2.4 mm wall thickness may sound a bit arbitrary at first, but it divides easily by the typical FDM nozzle diameter of 0.4 mm which makes slicing results more consistent and reliable. Most of us have at some point encountered a model where the slicer can’t quite decide how to handle a thin feature, delivering either a void between perimeters or an awkward attempt at infill, and this practice helps reduce that. Another tip is to minimize the number of sharp edges in the design, because rounded corners print more efficiently and with smoother motions from the print head.

The road to enclosures has many paths, including enclosures made from FR4 (aka PCB material) all the way down to scrap wood with toner transfer labeling, and certainly desktop 3D printing has been a boon to anyone who’s had to joylessly drill and saw away at a featureless plastic box.

Tightwad Hacks Label Printer, Beats Manufacturer at Own Game

Sometimes we hack for the thrill of making something new, and sometimes we hack to push back the dark veil of ignorance to shed fresh light on a problem. And sometimes, like when turning a used label printer into a point-of-sale receipt printer, we hack because we’re cheapskates.

We say that with the utmost respect and affection — there’s nothing to be ashamed of when your motive is strictly pecuniary. In [Dan Herlihy]’s case, hacking a cheap Brother label printer to use thermal paper meant saving $300 on a dedicated receipt printer. But it also meant beating Brother at their “Razor and Blades” business model that keeps you buying their expensive proprietary labels. A pattern of holes in the plastic label roll tells the printer what size labels are loaded, so [Dan] defeated that by breaking off a piece of the plastic and gluing it on the sensor. To convince the printer that plain thermal paper is label stock, he printed up a small strip of paper with the same pattern of black registration stripes that appear on the back of the labels. Pretty clever stuff, and it lets him print high-resolution receipts for his electronics shop on the seriously cheap.

[Dan]’s hack is simple, but may suffer from wear on the paper encoder strip. Perhaps this Brother hack using the gears as encoders will provide some inspiration for long-term fix.

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Bring Home a Classic Synth with the DIY Fairlight CMI

[Davearneson] built a modern version of a classic synthesizer with his DIY Fairlight CMI. If there were a hall of fame for electronic instruments, the Fairlight CMI would be on it. An early sampling synth with a built-in sequencer, the Fairlight was a game changer. Everyone from A-ha to Hans Zimmer has used one. The striking thing about the Fairlight was the user interface. It used a light pen to select entries from text menus and to interact with the audio waveform.

The original Fairlight units sold for £18,000 and up, and this was in 1979. Surviving units are well outside the price range of the average musician. There is an alternative though – [Peter Vogel] has released an iOS app which emulates the Fairlight.

[Davearneson] had an old iPad 2 lying around. Too slow to run many of the latest apps, but just fast enough to run the Fairlight app. An iPad doesn’t exactly look like a classic instrument though. So he broke out the tools and created a case that looked the part.

The front of the case is made of framing mat board. The rest of the shell is wood. [Davearneson] used Plasti-Dip spray to replicate the texture of 1970’s plastics. The audio interface is a Griffon unit, which provides audio and MIDI connections. [Davearneson] extended the connections from the Griffon to the rear of the case, making for a clean interface.

The iPad doesn’t exactly support a light pen, so a rubber tipped stylus on a coil cord takes it place. The result is a device that looks and works like a Fairlight – but doesn’t need a steady diet of 8″ floppy discs to operate.

Interested in classic digital synthesizers that are a bit more budget friendly? Check out Al Williams’ article on the SID chip, or this 3D printed synth based upon the 4046 PLL chip.

Run From the Sound of Footsteps in Blind Game of Tag

The human auditory system is a complex and wonderful thing. One of its most useful features is the ability to estimate the range and direction of sound sources – think of the way people instinctively turn when hearing a sudden loud noise. A team of students have leveraged this innate ability to produce a game of tag based around nothing but sound.

The game runs on two FPGAs, which handle the processing and communication required. The chaser is given a screen upon which they can see their own location and that of their prey. The target has no vision at all, and must rely on the sounds in their stereo headphones to detect the location of the chaser and evade them as long as possible.

The project documentation goes into great detail about the specifics of the implementation. The game relies on the use of the Head Related Transfer Function – a function related to how the ear picks up sounds relative to their position. This allows the FPGA to simulate the chaser’s footsteps, and feed the audio to the target who perceives the chaser’s position purely by sound.

It’s a great example of a gameplay mechanic that we’d love to see developed further. The concept of trying to find one’s way around by hearing alone is one which we think holds a lot of promise.

With plenty of processing power under the hood, FPGAs are a great choice for complex audio projects. A great project to try might be decoding MP3s.


Google Home Meets ESP8266

[Luc Volders] is building his own smart house with the help of Google Home and an ESP-8266. Inspired by the house computers from the TV show, Eureka [Luc] created an IoT ecosystem using a mix of off the shelf devices and open source software.

There are about a thousand ways to create a DIY smart home these days. All of them involve setting up a command receiver (like Amazon’s Echo or Google Home), some sort of cloud connection, and an end device controller. This can get complex for the beginner. [Luc’s] article is great because he walks is through each step tutorial style. He even keeps things simple by programming the ESP8266 using BASIC with ESP-BASIC.

[Luc] uses If This Then That (IFTT) as his cloud service. IFTT is the glue between Google’s cloud service and the ESP8266 connected to his home WiFi network. Speaking of which, [Luc] shows how to set up port forwarding on the router so all accesses to port 8085 go to the ESP8266. Not exactly strong security – but it’s better than opening the entire home network.

You don’t need a real Google home device for this hack. You can build your own with a Raspberry Pi. Once that is set up you can do everything from turning on lights to watering your lawn.

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Arise, Chicken, Arise!

A couple of months ago, [Mike] started saving bones from all the fried chicken he had been eating. If that’s the opening line, you know it’s going to be good.

This Cyborg Chicken project grew out of [Mike]’s love for battlebots, and an immense dearth of battleborgs. The difference, though small, is distinct: a robot is simply a machine that carries out instructions either automatically or via remote control. A cyborg, on the other hand, contains both organic and biomechatronic body parts. Since [Mike] was saving chicken bones, he stumbled upon the idea of creating a cyborg out of trash, a few servos, an MSP430, and some other parts sitting around in his junk drawer.

A continuation of an earlier remote controlled food project, the capabilities of these chicken battleborgs are about what you would expect: they roll around on wheels and flail their drumsticks wildly. [Mike] has already built at least two of these devices, and the result is accurately described as Rock ’em Sock ’em Borgs. Check out the video below for the action.

On the hardware side of things, [Mike] picked up an MSP430, and whipped up a bit of code in Java. Three billion enterprise computing systems and, now, two cyborg chickens run Java. The motors and drivers come from Pololu, and control is provided over IR with a pair of Atari joysticks.

You can check out the videos of these cyborg chickens below. If you have to ask why, the answer is always, ‘because’.

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Hackaday Prize Entry: Rangefinder + Camera = SmartZoom

The interesting thing about submissions for The Hackaday Prize is seeing unusual projects and concepts that might not otherwise pop up. [ken conrad] has a curious but thoughtfully designed idea for Raspberry Pi-based SmartZoom Imaging that uses a Pi Zero and camera plus some laser emitters to create a device with a very specific capability: a camera that constantly and dynamically resizes the image make the subject appear consistently framed and sized, regardless of its distance from the lens. The idea brings together two separate functions: rangefinding and automated zooming and re-sampling of the camera image.

The Raspberry Pi uses the camera board plus some forward-pointing laser dots as a rangefinder; as long as at least two laser dots are visible on the subject, the distance between the device and the subject can be calculated. The Pi then uses the knowledge of how near or far the subject is to present a final image whose zoom level has been adjusted to match (and offset) the range of the subject from the camera, in effect canceling out the way an object appears larger or smaller based on distance.

We’ve seen visible laser dots as the basis of rangefinding before, but never tied into a zoom function. Doubtlessly, [ken conrad] will update his project with some example applications, but in the meantime we’re left wondering: is there a concrete, practical use case for this unusual device? We have no idea, but we’d certainly have fun trying to find one.