3D Printed Speaker Uses DSP For Ultimate Performance

July 25, 2020 by Lewin Day 17 Comments

Speaker design used to be as much about woodwork as it was about advanced acoustic mathematics. In recent decades, technologies such as digital signal processing and 3D printing have changed the game significantly. Leaning heavily on these techniques, [ssashton] developed a design called Mr. Speaker.

The speaker contains a 3″ woofer for good bass response, and twin tweeters to deliver stereo audio. Using WinISD to help do the requisite calculations on porting and volume, [ssashton] designed a swooping 3D printed enclosure with a striking design. Sound comes into the unit through an off-the-shelf Bluetooth module, before being passed to an ADAU1401 digital signal processing unit. From there, it’s passed to a mono amp to drive the woofer and a stereo one for the tweeters.

To get the flattest frequency response possible and maintain linear phase, it’s all about DSP in this case. RePhase software was used to design a DSP filter to achieve these goals, helping the speaker to produce the desired output. The ADAU1401 DSP was then programmed using Sigma Studio, which also allows the designer to do things such as split outputs for seperate woofer and tweeter drives.

[ssashton] does a great job of explaining both DSP principles and old-school speaker design tricks, from phase plugs to reflections. The use of 3D printed parts to rapidly iterate the design is impressive, too. We’d love to see the final enclsoure get an acetone smoothing treatment to really take it over the edge.

If you’re into serious speaker design and want more, be sure to check out this advanced transmission line design. For those of you with your own builds with some nifty tricks, drop us a note on the tipline.

Simple Plasma Cutter Collision Detection System

July 25, 2020 by Lewin Day 7 Comments

Machine tools often have powerful drive motors, allowing them to work quickly and accurately to get the job done fast. However, this can cause major damage if the tool head collides with an unexpected object. To protect against such occurances, [Xnaron] developed a simple system to shut down his plasma cutter in the event of a crash.

The system consists of a 3D printed collar that fits around the plasma cutting torch. The collar has two mating parts, which are held together with three magnets and three ball bearings to act as a key, maintaining the correct orientation. Three limit switches are then fitted, held closed by the two mating halves. When the torch collides with an object, this causes the magnetic coupling to seperate, triggering one or more of the limit switches, and shutting down the machine safely.

Video of an unplanned collision shows the device working well. It’s a neat solution that could probably be adapted to other types of machine tool that don’t experience high lateral forces. Of course, if you don’t yet have a plasma cutter, you can always make your own. Video after the break.

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ESP8266 Makes A Wireless Card Reader

July 25, 2020 by Al Williams 19 Comments

You can find commercial USB sticks that can also connect via WiFi. But [Neutrino] made his own using an ESP8266 married to a card reader. It all starts with the old trick of soldering a header to an SD card adapter. The USB port is still there, but it is only for power. A 3.3 V regulator and an ESP12E board round out the hardware.

Of course, the trick is the software. Starting from a few examples, he wound up providing an FTP server that you can connect to and send or receive files using that protocol.

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Stop Bad Laws Before They Start

July 25, 2020 by Elliot Williams 88 Comments

With everything else going on this summer, you might be forgiven for not keeping abreast of new proposed regulatory frameworks, but if you’re interested in software-defined radio (SDR) or even reflashing your WiFi router, you should. Right now, there’s a proposal to essentially prevent you from flashing your own firmware/software to any product with a radio in it before the European Commission. This obviously matters to Europeans, but because manufacturers often build hardware to the strictest global requirements, it may impact everyone. What counts as radio equipment? Everything from WiFi routers to wearables, SDR dongles to shortwave radios.

The idea is to prevent rogue reconfigurable radios from talking over each other, and prevent consumers from bricking their routers and radios. Before SDR was the norm, and firmware was king, it was easy for regulators to test some hardware and make sure that it’s compliant, but now that anyone can re-flash firmware, how can they be sure that a radio is conformant? Prevent the user from running their own firmware, naturally. It’s pretty hard for Hackaday to get behind that approach.

The impact assessment sounds more like advertising copy for the proposed ruling than an honest assessment, but you should give it a read because it lets you know where the commission is coming from. Reassuring is that they mention open-source software development explicitly as a good to be preserved, but their “likely social impacts” include “increased security and safety” and they conclude that there are no negative environmental impacts. What do you do when the manufacturer no longer wants to support the device? I have plenty of gear that’s no longer supported by firmware updates that is both more secure and simply not in the landfill because of open-source firmware.

Similarly, “the increased capacity of the EU to autonomously secure its products is also likely to help the citizens to better protect their information-related rights” is from a bizarro world where you can trust Xiaomi’s home-automation firmware to not phone home, but can’t trust an open-source replacement.

Public comment is still open, and isn’t limited to European citizens. As mentioned above, it might affect you even if you’re not in the EU, so feel free to make your voice heard. You have until September, and you’ll be in some great company if you register your complaints. Indeed, reading through the public comments is quite heartening: Universities, researchers, and hackers alike have brought up reasons to steer clear of the proposed approach. We hope that the commission hears us.

Jet Airliner Nacelle Becomes A Unique Camper

July 25, 2020 by Jenny List 47 Comments

It’s possible that some of you will have thought about making a custom camper for yourselves. Some of you may even have gone as far as to build a teardrop caravan. It’s very unlikely though that you’ll have gone as far as [Steve Jones] though, who took an outer engine nacelle from a retired ex-RAF VC-10 airliner and converted it into a camper that is truly one of a kind.

On the face of it a jet engine nacelle should be an easy shell for such a project, but such a simplified view perhaps doesn’t account for the many vents, pipes, and hatches required by the engine in flight. Turning it into a waterproof housing for a camper was a significant job, which he has managed to do while leaving one set of engine access doors available as a large opening for a room with a view.

The nacelle is mounted on a narrowed former caravan chassis, and with an eye-catching window created from its former air intake and a very well executed interior fit-out it makes for a camper that many of us would relish trying for ourselves. You can see a video of it below the break, and we wish we could be lucky enough to encounter it in a campsite one summer.

We’ve shown you our share of campers over the years, but perhaps this 3D printed one has most appeal.

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This Tube Preamp Has A Nixie Volume Display

July 25, 2020 by Jenny List 15 Comments

The pursuit of audiophile hi-fi is one upon which many superlatives and perhaps a little too much money are lavished. But it’s also a field in which the self-builder can produce their own equipment that is as good or often better than that which can be bought, so it provides plenty of interesting projects along the way. [Justin Scott]’s tube preamplifier is a great example, with its novel use of a pair of Nixie tubes to indicate the volume to which it has been set.

The audio side of the preamp comes courtesy of a four-tube kit from tubes 4 hi-fi, in which we notice another tube as power supply rectifier. The case is a beautifully made wooden affair with a professional front panel, but it’s the Nixies which make it a bit special. A high quality motorised potentiometer is used as a volume control, one of its multiple outputs is used as a simple potential divider to provide a voltage. This is read by an Arduino, which in turn drives the Nixies via a BCD-to-decimal decoder. The attention to detail in the whole project is at a very high level, and though he’s not shred any of its audio measurements with us, we’d expect it to sound as good as it looks.

If tube amplifiers interest you, we’ve delved into their design in the past, and it’s worth directing you to Justin’s matching amplifier, as well.

Homebrew 16-Bit Computer Is A Wire-Wrapped Work Of Art

July 24, 2020 by Dan Maloney 9 Comments

Breadboard 8-bit computer builds seem all the rage these days, and with good reason: building your own CPU from the board up using discrete logic chips is a great way to really learn how microprocessors work. Not to mention that it’s an incredible flex. But once you’ve conquered the eight-bit, what do you do? Easy: build a 16-bit computer from 74HC logic chips.

Attentive readers will likely remember this computer’s builder, [Paulo Constantino], from his previous work on 8-bit breadboard computers. As gloriously entropic as that tangled mass of wires was, it must have been a nightmare for [Paulo] to maintain. And so when the time came to upgrade, he wisely chose a more integrated construction method. The construction method is wire-wrapping, with multiple cards plugged into backplane and connected by ribbon cables. The whole card cage is far neater than the previous build, and seems to lend itself to rapid modifications. The top card in the cage acts as a control panel for now; eventually, [Paulo] planes to put a real front panel on the cage to support all the switches and blinkenlights such builds demand. Stretch goals include supporting audio and video and getting the machine online so anyone can log in.

The video below is an overview of the current state of the machine; earlier videos in the playlist cover the design and build in more detail. We hope to see schematics soon, and we’d love to know where to get some of those wire-wrap PCBs for projects of our own.

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