Year: 2016

Hackaday Links: May 15, 2016

May 15, 2016 by 9 Comments

The Hackaday Overlords (or Hackaday family) are running a series of AMAs on SupplyFX. What is SupplyFX? It’s a social network for EEs. Who’s in the first AMA? [Brady Forrest], the guy who runs Highway1, a Bay Area hardware accelerator. They’re the accelerator responsible for the lustworthy Keyboardio, and the startup that is purely mechanical and has shipped zero lines of code, CoolChip. If you want to talk about hardware startups, [Brady] is your man. The AMA is tomorrow, May 16th, at 13:00 Pacific.

Makerbot is dead, or at least they will be soon. Whatever. Nothing of value was lost. Lulzbot, on the other hand, is going gangbusters. They saw eight hundred percent growth over the last two years. and $15M in revenue in 2015. They did this all with open source hardware and software, and using 3D printing in a manufacturing context. They’re the jewel of the Open Hardware movement, and a shining example of what Free Software can do.

The current generation of software defined radios started with the ubiquitous TV tuner dongles, and quickly graduated to the HackRF. You can only get so much bandwidth out of a USB 2.0 socket, and the newest and bestest SDR is the LimeSDR. They’re about halfway through their crowdfunding campaign (and halfway funded), and have finally changed out the USB A connector to a USB micro B connector. Good choice.

The ESP8266 is quickly becoming the go-to device for when you want a cheap way to put a sensor on the Internet. The only problem is programming it. No problem – here’s a bunch of Lua scripts that do 90% of everything. Need to read a PIR sensor? Light up a few LEDs? Put the data from a temperature and humidity on the Internet? There you have it.

The Vintage Computer Festival West is back on this year. We’ve gone to VCF East in New Jersey for a few years now, and had a few occasional outings to the southeast and midwest Vintage Computer Festivals over the years. This is the first time the west coast has had a Vintage Computer Festival in several years. It’s in Mountain View, on August 6th and 7th. Yes, that’s the same weekend as DEF CON.

E3D, makers of fine hot ends and 3D printer paraphernalia, have released a new kind of filament. It’s called Edge, it’s based on PET, and it prints as easily as PLA, with better mechanical properties than ABS. A few sample prints made from Edge were at this year’s Midwest RepRap Festival, and the Edge’s bridging ability is crazy. You need a heated bed for Edge and it’s sensitive to moisture, but it has some very interesting properties that can be cleverly exploited.

In other filament news, Colorfabb released a filament to print clear parts. Yes, that’s very weird. Clear parts require 100% infill, meaning it will use a lot of filament. It’s still very advanced wizardry, and I’m very interested in seeing the first print of a sanded and polished convex lens.

Holy Crap it’s the 3D printing edition of the links post. [Prusa] just released the latest version of the i3. It’s now bigger: 250x210x200mm build volume. The heated bed – [Prusa] was one of the first to experiment with PCB heated beds – is now vastly improved when looking at it through a FLIR. The Mk. 42 heated bed doesn’t have a hot center or cool corners. PEI sheet removes the need for blue painters tape, glass, aqua net, or glue sticks. The printer has self-test capabilities. The mechanics of the printer, especially the Z axis, are improved. [Prusa] will be selling this as a kit for ~19000 Czech Crowns or $699 USD, but he’s RepRap to the core. Buy a spool and start printing your next printer.

 

Classic Amplifier Reborn With Modern Transistors

May 15, 2016 by 26 Comments

Someone brought a dead Marantz amplifier to [Lansing]’s attention, a rather nice model from the 1980s with one channel entirely dead and the other very quiet. His account of its repair is straightforward, but provides some insights should you find yourself with a similar item on your bench.

Opening up the box, he was presented with 35 years of accumulated dust. It’s the annoying side of cracking open classic kit, we all have our dusty horror stories. His first task was routine: to replace all the unit’s capacitors. The mains voltage in France has gone up by 10 volts from 220V to 230V as part of EU harmonization in the years since the amp was built, so he used capacitors with an appropriately higher rating to compensate. We might have waited until the rest of the amp was proven fixed before splashing the cash on caps, but maybe we’re more thrifty.

The quiet channel fix turned out to be from a muting circuit designed to keep the amp quiet during the turn-on phase and suppress that annoying “thump”. A dead transistor replaced, and all was well. The dead channel though had a whole slew of dead transistors in it, which turned the problem from one of repair to one of transistor equivalence. Quite a few of the 1980s parts were no longer available, so modern replacements had to be found.

It is tempting to think of particularly all small-signal transistors as functionally equivalent. You will get away with this in logic and switching circuits in which the device is either On or Off and never in between, but in an audio amplifier like the Marantz things are not so simple. A lot of effort will have been made by the designers to calculate resistances for the current passing through them to deliver the right DC bias points without sending the circuit into wild oscillation. An important part of that calculation comes from the current gain of the transistors involved. [Lansing] had to carefully select his transistors for equivalence, though it some cases he had to do a bit of creative lead-bending to fit a different pin-out.

So, all dead transistors replaced with appropriate equivalents, and the amp was reborn. Success, and very much worth the effort!

We’ve covered a lot of amplifiers here in the past. Some were dead, like this little amp with blown capacitors or this smokin’ subwoofer. Others are more esoteric, like this ion wind 1KV tube creation.

AV Remote Control Teams Arduino With – Visual Basic?

May 15, 2016 by 33 Comments

A large installed base of powered speakers from a defunct manufacturer and a dwindling supply of working remote controls. Sounds like nightmare fuel for an AV professional – unless you take matters into your own hands and replace the IR remotes with an Arduino and custom software.

From the sound of it, [Steve]’s crew was working on AV gear for a corporate conference room – powered speakers and an LCD projector. It was the speakers that were giving them trouble, or rather the easily broken or lost remotes. Before the last one gave up the ghost, [Steve] captured the IR codes for each button using an Arduino and the IRRemote library. With codes in hand, it was pretty straightforward to get the Nano to send them with an IR LED. But what makes this project unique is that the custom GUI that controls the Arduino was written in the language that everyone loves to hate, Visual Basic. It’s a dirty little secret that lots of corporate shops still depend on VB, and it’s good to see a little love for the much-maligned language for a change. Plus it got the job done.

Want to dive deeper into IR? Maybe this primer on cloning IR remotes with an Arduino will help. And for another project where VB shines, check out this voice controlled RGB LED lamp.

Super Strong 3D Component Carbon Fiber Parts

May 15, 2016 by 20 Comments

[prubeš] shows that parts printed with carbon fiber filament are as strong, or at least as stiff, as you’d expect. He then shows that his method for producing carbon fiber parts with a mixture of traditional lay-up and 3D printing is even stronger and lighter.

[prubeš] appears to be into the OpenR/C project and quadcopters. These things require light and strong parts for maximum performance. He managed to get strength with carbon fiber fill filament, but the parts weren’t light enough. Then he saw [RichMac]’s work on Thingiverse. [RichMac] designed parts with pre-planned grooves in which he ran regular carbon fiber tow with epoxy. This produced some incredibly strong parts. There’s a section in his example video, viewable after the break, where he tests a T joint. Even though the plastic starts to fail underneath the carbon fiber, the joint is still strong enough that the aluminum tube inside of it fails first.

[prubeš] innovation on [RichMac]’s method is to remove as much of the plastic from the method as possible. He designs only the connection points of the part, and then designs a 3D printable frame to hold them in place. After he has those in hand, he winds the tow around the parts in a sometimes predetermined path. The epoxy cures onto the 3D print creating a strong mounting location and the woven carbon fiber provides the strength.

His final parts are stronger than 100% infill carbon fill prints, but weighs 8g instead of 12g.  For a quadcopter this kind of saving can add up fast.

Continue reading “Super Strong 3D Component Carbon Fiber Parts” →

Propane Tanks Transformed Into Extreme Sandblaster

May 15, 2016 by 17 Comments

The [Make It Extreme] team has been racking up the builds lately, and a lot of them are heavy with metalworking. When you’re doing that kind of work, and you put as much care into finishing your builds like they do, it’s a good idea to have access to a sandblaster. So naturally, they built a really nice one.

We’ve featured a couple of [Michalis Mavros] and team’s build recently; you’ll no doubt recall this viciously effective looking spot welder and a sketchy angle grinder cum belt sander. The sandblaster build, centered as it is around scrap propane tanks, has some lethal potential, but luckily the team displaced any remaining gas from the tanks with water before doing any cutting. The design allows for a lot of sand in the tanks, with plans to provide a recycling system for the grit, which is a nice touch. And it works great – they even used it to clean it up before final finishing in the trademark [Make It Extreme] green and black paint job.

What we really like about the video, though, is that it’s a high-speed lesson on metalworking techniques. There’s a ton to learn here about all the little tricks needed to bring a large-scale metalworking project to fruition. It also demonstrates that we really, truly need a plasma cutter and a metalworking lathe.

Continue reading “Propane Tanks Transformed Into Extreme Sandblaster” →

Taming A Variac With A Thermistor

May 15, 2016 by 18 Comments

The folks at TOG, Dublin Hackerspace, have a large variac. A variac is a useful device for testing some fault conditions with AC mains powered equipment, it allows an operator to dial in any AC output voltage between zero, and in the case of TOG’s variac, 250V.

Their problem was with such a magnificent device capable of handling nearly 3KW, it presented an inductive load with a huge inrush current at power-on that would always take out the circuit breakers. Breakers come with different surge current handling capabilities, evidently their building is fitted with the domestic rather than the industrial variants.

Their solution was a simple one, they fitted an NTC surge limiter in series with the variac input. This is a thermistor whose resistance falls with temperature. Thus on start-up it presented an extra 12 ohm load which was enough to keep the breaker happy, but soon dropped to a resistance which left the variac with enough juice.

This is a simple fix to a problem that has faced more than one hackerspace whose imperfect lodgings are wired to domestic-grade spec. In a way it ties in neatly with our recent feature on mains safety; making the transformer no longer a pain to use means that it is more likely to be used when it is needed.

Via: TOG, Dublin Hackerspace.

Hackaday Prize Entry: DIY Ceramic PCBs

May 14, 2016 by 10 Comments

We’ve seen hundreds of ways to create your own PCBs at home. If you have a laser printer, you can put traces on a piece of copper clad board. If you have some hydrogen peroxide and acid, you can etch those traces. Don’t have either? Build a tiny mill and cut through the copper with a Dremel. Making your own PCBs at home is easy, provided your boards are made out of FR4 and copper sheets.

Printed circuit boards can be so much cooler than a piece of FR4, though. Ceramic PCBs are the height of board fabrication technology, producing a very hard board with near perfect electrical properties, high thermal conductivity, and a dielectric strength similar to mineral transformer oil. Ceramic PCBs are for electronics going to space or inside nuclear reactors.

For his entry into this year’s Hackaday Prize, [Chuck] is building these space grade PCBs. Not only is he tackling the hardest challenge PCB fabrication has to offer, he’s building a machine to automate the process.

The basic process of building ceramic PCBs is to create a sheet of alumina, glass powder, and binder. This sheet is first drilled out, then silver ink is printed on top. Layers of these sheets are stacked on top of each other, and the whole stack is rammed together in a press and fired in a furnace.

Instead of making his own unfired ceramic sheets, he’s just buying it off the shelf. It costs about a dollar per square inch. This material is held down on a laser cutter/inkjet combo machine with a vacuum table. It’s just a beginning, but [Chuck] has everything he needs to start his experiments in creating truly space grade PCBs.

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