Turning On Your Amplifier With A Raspberry Pi

Life is good if you are a couch potato music enthusiast. Bluetooth audio allows the playing of all your music from your smartphone, and apps to control your hi-fi give you complete control over your listening experience.

Not quite so for [Daniel Landau] though. His Cambridge Audio amplifier isn’t quite the latest generation, and he didn’t possess a handy way to turn it on and off without resorting to its infrared remote control. It has a proprietary interface of some kind, but nothing wireless to which he could talk from his mobile device.

His solution is fairly straightforward, which in itself says something about the technology available to us in the hardware world these days. He took a Raspberry Pi with the Home Assistant home automation package and the LIRC infrared subsystem installed, and had it drive an infrared LED within range of the amplifier’s receiver. Coupled with the Home Assistant app, he was then able to turn the amplifier on and off as desired. It’s a fairly simple use of the software in question, but this is the type of project upon which so much more can later be built.

Not so many years ago this comparatively easy project would have required a significant amount more hardware and effort. A few weeks ago [John Baichtal] took a look at the evolution of home automation technology, through the lens of the language surrounding the term itself.

Via Hacker News.

Sorry US; Europeans Listen to Space with GRAVES

In Europe, the GRAVES radar station beams a signal on 143.050 MHz almost straight up to detect and track satellites and space junk. That means you will generally not hear any signal from the station. However, [DK8OK] shows how you can–if you are in Europe–listen for reflections from the powerful radar. The reflections can come from airplanes, meteors, or spacecraft. You can see a video from [way1888] showing the result of the recent Perseid meteor shower.

Using a software-defined radio receiver, [DK8OK] tunes slightly off frequency and waits for reflections to appear in the waterfall. In addition to observing the signal, it is possible to process the audio to create more details.

Why is there a giant vertical radar transmitter in the middle of France? The transmitter uses a phased array to send a signal over a 45-degree swath of the sky at a time. It makes six total steps every 19.2 seconds. A receiver several hundred miles away listens for reflections.

Even the moon reflects the signal when it is in the radar’s path. If you are interested in a moon bounce, you may be able to build a station to hear the reflections without being in Europe.

Of course, if you can transmit yourself, you might want to bounce your own signal off airplanes. If you want to do it old school, you could emulate [Zoltán Bay].

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Hackaday Links: August 27, 2017

Hulk Hands! Who remembers Hulk Hands? These were a toy originally released for the 2003 Hulk movie and were basically large foam clenched fists you could wear. Hulk Hands have been consistently been re-released for various Marvel films, but now there’s something better: it’s the stupidest tool ever. Two guys thought it would be fun and not dangerous at all to create cast iron Hulk Hands and use them as demolition and renovation equipment. This is being sold as a tool comparable to a sledgehammer or a wrecking bar.

New Pogs! We’re up to 0x0C. Is your collection complete?

[Peter] is building an airplane out of foam in his basement. He’s also doing it as a five or six-part series on his YouTube channel. Part two is now up. This update covers the tail surfaces, weighing and balancing the fuselage, and a general Q&A with YouTube comments.  Yes, [Peter] still has a GoFundMe up for a parachute, and it’s already about half funded. With any luck, he’ll have the $2600 for a parachute before he builds the rest of the plane. Another option is a ballistic parachute system — a parachute for the whole plane, like a Cirrus. That would be a bit more than $4000, so we’ll see how far the GoFundMe goes.

Hey, remember the Nvidia Jetson TX1? It’s a miniATX motherboard running a fast ARM core with a GPU housing 256 CUDA cores. It’s cool, and the new version — the TX2 — is designed for ‘machine learning at the edge’. They’re on sale now, for only $199.

Primitive Technology has another video out. This time, he’s improving his bow string blower into something that kinda, sorta resembles a modern forge. This time, the experiment was a success when it comes to pottery — he’s now able to fire clay at a much higher temperature, bringing him reasonably close to modern ceramics. At least, as close as you can get starting with the technology of a pointed stick. The experiment was marginally successful when it came to creating iron. He’s using iron-bearing bacteria (!) for his source of ore and was able to smelt millimeter-sized pellets of iron. This guy needs a source of copper or tin. Zinc is also surprisingly possible given his new found capabilities for ceramics.

Hackaday Prize Entry: The Weedinator Project, Now with Flame

We like that the Weedinator Project is thinking big for this year’s Hackaday Prize! This ambitious project by [TegwynTwmffat] is building on a previous effort, which was a tractor mounted weeding machine (shown above). It mercilessly shredded any weeds; the way it did this was by tilling everything that existed between orderly rows of growing leeks. The system worked, but it really wasn’t accurate enough. We suspect it had a nasty habit of mercilessly shredding the occasional leek. The new version takes a different approach.

The new Weedinator will be an autonomous robotic rover using a combination of GPS and colored markers for navigation. With an interesting looking adjustable suspension system to help with fine positioning, the Weedinator will use various attachments to help with plant care. Individual weeds will be identified optically and sent to the big greenhouse in the sky via precise flame from a small butane torch. It’s an ambitious project, but [TegwynTwmffat] is building off experience gained from the previous incarnation and we’re excited to see where it goes.

3D Printing T-Shirt Designs

Usually, t-shirt designs are screen printed, but that’s so old school. You have to make the silkscreen and then rub paint all over – it’s clearly a technique meant for the past. Well, fear not, as [RCLifeOn] is here to bring us to the future with 3D Printed T-Shirt Designs.

[RCLifeOn] affixes t-shirts to his print build platform and boom: you’ve got 3D printed graphics. He started by using PLA which, while it looked great, wasn’t up to a tussle with a washing machine. However, he quickly moved on to NinjaFlex which fended much better in a wash cycle. While the NinjaFlex washed better, [RCLifeOn] did have some issues getting the NinjaFlex to adhere to the t-shirt. With a little persistence and some settings tweaking, he was able to come out ahead with a durable and aesthetically pleasing result.

Now, 3D printing isn’t going to replace screen printing, but it’s also not going to replace injection molding. What 3D printing lacks in speed and efficiency, it makes up in setup time & cost. In other words, if you need 50 t-shirts of the same design, screen printing is the way to go. But, if you need 50 shirts, each with a different design, you just might want to follow in [RCLifeOn’s] footsteps.

Anyways, we don’t have much on 3D printing t-shirts, but we do have other useful information on 3D printing slinkys and 3D printing project enclosures. And, if you’d rather do it the old-school way, we can show you how to silkscreen all the things.

3D Printer Tool Changer Gives You Access to Lots of Extruders

The benefits of having a 3D printer with multiple extruders are numerous: you can print soluble support material for easy removal, print a combination of flexible and rigid filament, or simply print in different colors. Unfortunately, traditional multi-extruder setups have some serious drawbacks, even aside from the cost.

Usually, the extruders are all mounted next to each other on a single carriage. This increases the mass, which can cause print quality issues like shadowing. It also reduces the printable area, as each extruder needs to be able to reach the entire area. All of this means that the design becomes more and more impractical with each extruder you add, and that’s why it’s uncommon to see more than two extruders on a printer.

Over on Hackaday.io, [rolmie] has come up with a very practical (and affordable) solution to this problem. He has designed a tool changer that gives the printer the ability to switch out hot ends on the fly. The system is very similar to the tool changers we see on CNC machining centers: tools (the hotends) are stored on a rack, and a tool change in the G-code sends the carriage over to the rack to drop off the old hotend and pick up a new one.

The benefit of the design is that both the mass and volume of the carriage are kept to a minimum, while allowing you to use many different hot ends. Each hotend’s settings can be configured individually, and you can even use different models of hotend altogether (maybe one model works better for PLA, while another is better for ABS). The design is still in the prototyping stage and needs some refinement, but it’s a very promising proof of concept that seems like it could be implemented fairly easily into most 3D printer models.

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Casting Metal Directly Into 3D Printed Molds

Casting metal and 3D printing go together like nuts and gum, and there are no shortage techniques that use the two together. Lost PLA casting is common, and sculptors are getting turned on to creating their works in plastic first before sending it off to the foundry. Now the folks at FormLabs have turned the whole ‘casting metal and 3D printer’ thing on its head: they’re printing sacrificial molds to cast pewter.

There are two techniques demonstrated in this tutorial, but the real winner here is printing a complete sacrificial mold for pewter miniatures. While this technique requires a little bit of work including washing, curing, and a bit of post-processing, you would have to do that anyway with anything coming out of a resin printer.

The material of choice for these molds is a high temp resin with a heat deflection temperature of 289 °C. Using a pewter alloy that melts at 260 °C, casting a metal miniature is as simple as pouring molten metal into a mold. Demolding might be a little finicky, but with a small screwdriver used as a chisel, it’s possible to get the cast newly parts out.

We’ve seen pewter casting with PLA, but the quality available from the Form resin printers is truly amazing and produces some great looking miniatures.