Amplifier Controlled Motorized Display

It’s easy to get jaded by gadgets like the Chromecast or Sonos, which let the user control AV equipment remotely from a mobile device or computer. You can pick something to play from your phone and send it off to your speakers via the magic of Wi-Fi. But it’s still nice to have a display to look at for music visualizations and that sort of thing, at least occasionally.

To address this only occasional desire to have a display on your media setup, you could follow in the footsteps of [Steven Elliott] and create a DIY motorized display which only pops up when needed. Inspired by seeing videos of TVs rising out of cabinets and other such trickery, he decided to create his own version using an old computer monitor he had lying around.

The monitor is lifted with a beefy linear actuator, which has been placed inside of a square metal fence post to keep from rotating. It already had a power supply and control board with relays for extending and retracting, so [Steven] just needed to find a convenient way of firing them off.

The answer came from a somewhat unconventional source: his amplifier. [Steven] explains that many amplifiers feature a “Trigger Output”, which uses a standard stereo 3.5mm connector and sends a 12V pulse to connected device. This is generally used to turn on downstream devices when the amplifier switches to the respective input. It’s too short and not nearly powerful enough to close the actuators relays, but it’s easy enough to detect.

[Steven] uses a LeoStick microcontroller to wait for the pulse from the amplifier, and then use that to raise or lower the display depending on the selected input. There’s also a SPST momentary switch which can be used to trigger the actuator manually. Beyond the fact the linear actuator is a bit loud, he says the setup works very well and prevents him from having to start up his projector if he just wants to take a quick glance at what’s playing or program his DVR.

We don’t see many motorized display lifts like this anymore, not since wall mounted LCDs became popular anyway. But it’s still a cool effect, and today made quite a bit easier thanks to the fact that TVs and monitors no longer weigh as much as a small car.

[Thanks to Baldpower for the tip.]

Voice Controlled Stereo Balance With ESP8266

A stereo setup assumes that the listener is physically located between the speakers, that’s how it can deliver sound equally from both sides. It’s also why the receiver has a “Balance” adjustment, so the listener can virtually move the center point of the audio by changing the relative volume of the speakers. You should set your speaker balance so that your normal sitting location is centered, but of course you might not always be in that same position every time you listen to music or watch something.

[Vije Miller] writes in with his unique solution to the problem of the roving listener. He’s come up with a system that can adjust the volume of his speakers without having to touch the receiver’s setup, in fact, he doesn’t have to touch anything. By leveraging configurable voice control software running on his computer, his little ESP8266-based devices do all the work.

Each speaker has its own device which consists of a NodeMCU ESP8266 and X9C104 digital potentiometer inside of a 3D printed case. The audio terminal block on the gadget allows him to connect it inline between the speaker and the receiver, giving [Vije] the ability to adjust the volume through software. The source code, which he’s posted on the project page, uses a very simple REST-style API to change speaker volume based on HTTP requests which hit the ESP8266’s IP address.

The second part of the project is a computer running VoiceAttack, which lets [Vije] assign different actions based on what the software hears. When he says the appropriate command, the software goes through and fires off HTTP requests to the nodes in the system. Everything is currently setup for two speakers, but it shouldn’t be too difficult to expand to more speakers (or even rooms) with some adjustment to the software.

It’s not the first voice controlled speaker we’ve ever seen, but it does solve a very specific problem in a unique way. We’d be interested in seeing the next logical step, which would see this technology integrated into the speaker itself.

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Cross-Correlation Makes Quick Work Of Ads

Once relegated to the proverbial Linux loving Firefox user, ad blocking has moved into public view among increased awareness of privacy and the mechanisms of advertising on the internet. At the annual family gathering, when That Relative asks how to setup their new laptop, we struggle through a dissertation on the value of ad blockers and convince them to install one. But what about mediums besides the internet? Decades ago Tivo gave us one button to jump through recorded TV. How about the radio? If available, satellite radio may be free of The Hated Advertisement. But terrestrial radio and online streams? [tomek] wasn’t satisfied with an otherwise sublime experience listening streaming Polish Radio Three and decided to build a desktop tool to detect and elide ads from the live audio stream.

[tomek] was aware of this hip knowledge domain called Digital Signal Processing but hadn’t done any of it themselves. Like many algorithmic problems the first step was to figure out the fastest way to bolt together a prototype to prove a given technique worked. We were as surprised as [tomek] by how simple this turned out to be. Fundamentally it required a single function – cross-correlation – to measure the similarity of two data samples (audio files in this case). And it turns out that Octave provides it in the box. After snipping the start-of-ad jingle out of a sample file and comparing it to a radio program [tomek] got the graph at the left. The conspicuous spike is the location of the jingle in the audio file.

At this point all that was left was packaging it all into a one click tool to listen to the radio without loading an entire analysis package. Conveniently Octave is open source software, so [tomek] was able to dig through its sources until they found the bones of the critical xcorr() function. [tomek] adapted their code to pour the audio into a circular buffer in order to use an existing Java FFT library, and the magic was done. Piping the stream out of ffmpeg and into the ad detector yielded events when the given ad jingle samples were detected.

[tomek] packaged that tool into a standalone executable, but the gem here is the followup post. After removing ads in the online stream they adapted a RaspberryPi to listen to an FM receiver and remote control their Yamaha tuner over the network. So when the tuner is playing Radio Three the Pi notices and ducks the audio appropriately to avoid those pesky ads. Video of this after the break.

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An Upcycled Speaker Box with Hidden Features

At first glance, this fire engine red speaker box built by [NoshBar] looks straightforward enough. Just an MDF case and couple of drivers recovered from a trashed stereo. But the array of controls and connectors on the front, and a peek on the inside, shows there’s more to this particular project than meets the eye.

Built almost entirely from parts [NoshBar] found in the trash, construction started with some salvaged MDF IKEA shelves and their corresponding twist lock cam fittings. We don’t usually see those style cam fittings used to build DIY enclosures, but if it works for all those furniture manufacturers why not?

A pair of Sony stereo speakers he found gave up their internals, and a TPA3116 amplifier board off of eBay drives them. He’s wired up an audio pass-through mode for using headphones when the amplifier is powered off, and dual inputs so he can switch between PC and PS4.

But the audio components are only half of what’s inside that shiny red exterior. [NoshBar] packed in an ATX PSU and broke out the 3.3 V, 5 V, and 12 V lines to the front panel so he can use it as a bench power supply for his Arduino projects. It’s also home to a gigabit Ethernet switch and a Raspberry Pi acting as a file server.

We’re always amazed at what hackers are able to accomplish with parts they’ve literally pulled out of the trash, from a waterwheel to charge your phone to a functional CNC router. It seems there’s plenty of treasure in your local dumpster if you’re willing to get a little dirty.

Hacked LCD Shutter Glasses See The Light

It’s always a little sad to see a big consumer technology fail. But of course, the upside for us hacker types is that the resulting fire sale is often an excellent source for hardware that might otherwise be difficult to come by. The most recent arrival to the Island of Unwanted Consumer Tech is 3D TV. There was a brief period of time when the TV manufacturers had nearly convinced people that sitting in their living room wearing big dorky electronic glasses was a workable solution, but in the end we know how it really turned out.

Those same dorky glasses are now available for a fraction of their original price, and are ripe for hacking. [Kevin Koster] has been playing around with them, and he’s recently came up with a circuit that offers the wearer a unique view of the world. Any reflective surface will look as though it is radiating rainbows, which he admits doesn’t show up as well in still images, but looks cool enough that he thought it was worth putting the board into production in case anyone else wants in on the refraction action.

To explain how it works, we need to take a couple of steps back and look at the mechanics of the LCD panels used in these type of glasses. At the risk of oversimplification, one could say that LCDs are sort of like capacitors: when charged the crystals align themselves in such a way that the polarization of the light passing through is changed. Combined with an external polarization filter, this has the end result of turning the panel opaque. To put the crystals back in their original arrangement, and let the light pass through again, the LCD panel is shorted out in the same way you might discharge a capacitor.

What [Kevin] found was that if he slowly discharged the LCD panel rather than shorting it out completely, it would gradually fade out instead of immediately becoming transparent. His theory is that this partial polarization is what causes the rainbow effect, as the light that’s passing through to the wearers eyes is in a “twisted” state.

[Kevin] has provided all of the information necessary to build your own “Rainbow Adapter”, but you can also purchase a kit or assembled board from Tindie. If you’re looking for other projects to make use of those 3D glasses collecting dust, how about turning them into automatic sunglasses or having a go at curing your lazy eye.

A Unique Microphone Preamp

We live in a world in which nearly any kind of gadget or tool you can imagine is just a few clicks away. In many respects, this has helped fuel the maker culture over the last decade or so; now that people aren’t limited to the hardware that’s available locally, they’re able to create bigger and better things than ever before. But it can also have a detrimental effect. One has to question, for instance, why they should go through the trouble of building something themselves when they could buy it, often for less than the cost of the individual components.

The critic could argue that many of the projects that grace the pages of Hackaday could be supplanted with commercially available counterparts. We don’t deny it. But the difference between buying a turn-key product and building an alternative yourself is that you can make it exactly how you want it. That is precisely why [Sam Izdat] created this truly one of a kind microphone preamplifier. Could he have bought one online for cheaper? Probably. Could he have saved himself an immense amount of time and effort? Undoubtedly. Do we care? Not in the slightest.

The amplifier is based on the Texas Instruments INA217 chip, with an Arduino Nano and 128×64 OLED display providing the visualization. [Sam] was able to find a bare PCB for a typical INA217 implementation on eBay for a few bucks (see what we mean?), which helped get him started and allowed him to spend more time on the software side of things. His visualization code offers a number of interesting display modes, uses Fast Hartley Transforms, and very nearly maxes out the Arduino.

But perhaps no element of this build is as unique as the case. The rationale behind the design is that [Sam] wanted to compartmentalize each section of the device (power supply, amplifier, visualization) to avoid any interference. The cylindrical shapes were an issue of practicality: the compartments were constructed by using a hole saw to make wooden discs, which were then glued together and hollowed out. The case was stained and coated with polyurethane, but due to some slightly overzealous use of glue and fillers, the coloring isn’t uniform. This gives the final piece a somewhat weathered look, in sharp contrast to the decidedly high-tech looking display.

Overall, this build reminds us of the modular 3D printed amplifier we saw earlier in the year combined with these speaker-integrated Arduino VU meters.

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Playing Jedi Mind-Tricks On Your TV

Gesture-enabled controls mean you get to live out your fantasy of wielding force powers. It does, however, take a bit of hacking to make that possible. Directly from the team at [] comes a hand gesture controller for Jedi mind-trick manipulation of your devices!

The star of the show here is the APDS-9960 RGB and gesture sensor, with an Arduino Pro Mini 328 doing the thinking and an IR transmitter LED putting that to good use. The Arduino Sketch is a chimera of two code examples for IR LEDs and the gesture sensor — courtesy of the always estimable Ken Shirriff, and SparkFun respectively.

Of course, you can have the output trigger different devices, but since this particular build is meant to control a TV the team had to use a separate Arduino and IR receiver to discover the codes for the commands they wanted  to use. Once they were added to the Sketch, moving your hand above the sensor in X, Y or Z-axes executes the command. Voila! — Jedi powers.

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