Retrotechtacular: Apex Radio — The Forgotten HiFi

July 31, 2018 by Al Williams 5 Comments

Broadcasting has changed a lot in the last few decades. We have satellite radio, internet streaming, HD radio all crowding out the traditional AM and FM bands. FM became popular because the wider channels and the modulation scheme allowed for less static and better sound reproduction. If you’ve never tried to listen to an AM radio station at night near a thunderstorm, you can’t appreciate how important that is. But did you know there was another U.S. broadcast band before FM that tried to solve the AM radio problem? You don’t hear about it much, but Apex or skyscraper radio appeared between 1937 and 1941 and then vanished with the onslaught of FM radio.

If you’ve heard of Apex radio — or if you are old enough to remember it — then you are probably done with this post. For everyone else, consider what radio looked like in 1936. The AM band had 96 channels between 550 and 1500 kHz. Because those frequencies propagate long distances at night, the FCC had a complex job of ensuring stations didn’t interfere with each other. Tricks like carefully choosing the location of stations, reducing power at night, or even shutting a station down after dark, were all used to control interference.

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Are Patent Claims Coming For Your WS2812?

July 31, 2018 by Jenny List 115 Comments

There are some components which are used within our sphere so often as to become ubiquitous, referred to by their part number without the need for a hasty dig through a data sheet to remind oneself just what we are talking about. You can rattle a few of them off, the 555, the 741, the ESP8266, and so on.

In the world of LEDs, the part that most immediately springs to mind is the Worldsemi WS2812 addressable LED. This part consists of three LEDs in red, green, and blue, all in the same package with a serial interface allowing a chain of individually addressable multicolour lights to be created. We’ve seen them in all sorts of places, and if you don’t recognise the part number then perhaps you will by one of the names they’re sold under: Neopixel.

Yesterday we received an email from our piratical friends at Pimoroni, the British supplier of all forms of electronic goodies. Among their range they have a reasonable number of products containing WS2812s, and it was these products that had formed the subject of an unexpected cease-and-desist letter. APA Electronic are the manufacturer of the APA102 addressable LED (which you may know as the Dotstar), and their cease-and-desist asking for the products to be withdrawn from sale rests on their holding a patent for an addressable multicolour LED. We’d be very interested to hear whether any other suppliers of WS2812-based parts have received similar communications.

US patent number 8094102B2 is indeed a patent for a “Single full-color LED with driving mechanism”, which does look a lot like a WS2812. But as always, such things are not as cut-and-dried as they might first appear. The LED in the patent for example relies upon a clock line for its operation, while the Worldsemi part doesn’t. I am not a lawyer so I’d hesitate to call this a baseless and speculative move, but I suspect that there will be plenty over which the two semiconductor companies can duke it out in the courtroom.

It’s fair to say that a large part of the ethos of our movement shares something with that of the world of open-source, so news of legal manoeuvres such as this are never likely to go down well. We’re small fry in this context and our commercial influence on APA102 or WS2812 sales will be minimal, but inevitably APA’s standing in our eyes will be diminished. Companies such as Pimoroni are not the target but a piece of collateral damage in a battle between manufacturers.

Whether the patent has been violated or not can only be decided by the courts. It is not uncommon for patent holders to go after companies selling the “infringing” products in hopes that rather than risk a costly court battle, they simply adhere to the demands, in this case buying parts from APA and not from Worldsemi.

So, if you rely on addressable LEDs, watch out! There may be trouble ahead.

Header image: Tristan Robitaille [CC BY-SA 4.0].

The Precise Science Of Whacking A Wine Glass

July 31, 2018 by Ben James 12 Comments

It’s common knowledge that tapping a wine glass produces a pitch which can be altered by adjusting the level of the tipple of choice inside. By filling twelve glasses with different amounts of liquid and tuning them to the twelve notes of the scale, it’s possible to make a one-octave instrument – though the speed and polyphony are bottle-necked by the human operator. If you think it sounds like a ripe project for automation, you’re correct: [Bitluni’s lab] has done what needed to be done, and created a MIDI instrument which plays the glasses using mallets.

Electronically it’s a simple build – some 12 V solenoids driven by MOSFETs, with an Arduino in charge. For the mechanical build, a 3D printer proved very useful, as each mallet could be made identical, ensuring a consistent tone across all glasses. Rubber covers printed in flexible filament were fitted to reduce the overtones and produce a clearer sound. [Bitluni] also utilised different types of glasses for the low and high pitches, which also helped to improve the clarity of the tone.

MIDI is of course the perfect protocol for this application; simple, lightweight and incredibly widely used, it’s the hacker’s delight for projects like this. The instrument can perform pre-programmed sequences, or be played live with a MIDI controller. Both of these are shown in the video after the break – stick around for a unique rendition of Flight Of The Bumblebee. For a more compact wine glass based music creation solution, we recommend this nifty project, which alters pitch using a water balloon raised and lowered into the glass by a servo. Continue reading “The Precise Science Of Whacking A Wine Glass” →

Kepler Planet Hunter Nears End Of Epic Journey

July 31, 2018 by Tom Nardi 50 Comments

The Kepler spacecraft is in the final moments of its life. NASA isn’t quite sure when they’ll say their last goodbye to the space telescope which has confirmed the existence of thousands of exoplanets since its launch in 2009, but most estimates give it a few months at best. The prognosis is simple: she’s out of gas. Without propellant for its thrusters, Kepler can’t orient itself, and that means it can’t point its antenna to Earth to communicate.

Now far as spacecraft failures go, propellant depletion isn’t exactly unexpected. After all, it can’t pull into the nearest service station to top off the tanks. What makes the fact that Kepler will finally have to cease operations for such a mundane reason interesting is that the roughly $600 million dollar space telescope has already “died” once before. Back in 2013, NASA announced Kepler was irreparably damaged following a series of critical system failures that had started the previous year.

But thanks to what was perhaps some of the best last-ditch effort hacking NASA has done since they brought the crew of Apollo 13 home safely, a novel way of getting the spacecraft back under control was implemented. While it was never quite the same, Kepler was able to continue on with modified mission parameters and to date has delivered so much raw data that scientists will be analyzing it for years to come. Not bad for a dead bird.

Before Kepler goes dark for good, let’s take a look at how NASA managed to resurrect this planet hunting space telescope and greatly expand our knowledge of the planets in our galaxy.

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Add-On Board Brings Xbox 360 Controllers To N64

July 31, 2018 by Tom Nardi 22 Comments

Many of the games released on the Nintendo 64 have aged remarkably well, in fact a number of them are still considered must-play experiences to this day. But the years have not been so kind to the system’s signature controller. While the N64 arguably defined the console first person shooter (FPS) genre with games like “Goldeneye” and “Perfect Dark”, a modern gamer trying to play these classics with the preposterous combination of analog and digital inputs offered by the N64 controller is unlikely to get very far.

Of course, you could play N64 games in an emulator and use whatever controller you wish. But where’s the challenge in taking the easy way out? [Ryzee119] would much rather take the insanely complex route, and has recently completed work on an add-on board that let’s you use Xbox 360 wireless controllers on Nintendo’s 1996 console. He’s currently prepping schematics and firmware for public release, with the hope that support for additional USB controllers can be added by the community.

Nintendo historians may recall that the N64’s controllers had an expansion port on the bottom where you would connect such accessories as the “Rumble Pak” and “Controller Pak”. The former being an optional force feedback device, and the latter a rather oddly named memory card for early N64 games which didn’t feature cartridge saves. Only “90’s Kids” will recall the struggle of using the “Rumble Pak” when a game required the “Controller Pak” to save progress.

Thankfully [Ryzee119] has solved that problem by adding battery backed storage to his adapter along with some clever code which emulates the “Controller Pak”. Similarly, the “Rumble Pak” is emulated by the Xbox 360 controller’s built-in force feedback and a bit of software trickery. Specific button combinations allow for enabling and disabling the various virtual accessories on the fly.

But the best part of this modification might be how unobtrusive the whole thing is. Not only does it allow you to still use the original controllers and accessories if you wish, but it only requires soldering a handful of wires to the console’s motherboard. Thanks to the surprising amount of dead space inside the system’s case, it’s not even a challenge to fit the board inside. You do need to use the official USB Xbox 360 controller receiver, but even here [Ryzee119] opted to put a USB port on the board so you could just plug the thing in rather than having to cut the connector off and trying to solder it to the board yourself.

It probably won’t come as a surprise that this isn’t the first time [Ryzee119] has fiddled with the internals of a classic Nintendo system. We’ve previously covered his fantastic custom PCB to fit a Raspberry Pi Zero into a GameBoy Advance.

[Thanks to Gartral for the tip.]

Building The Terminator’s Arm

July 31, 2018 by Lewin Day 11 Comments

The Cyberdyne Systems Series 800 Terminator is a highly capable robot that happens to look an awful lot like Arnold Schwarzenegger. It boasts an advanced metallic endoskeleton, which has been the inspiration for many DIY prop builds over the years. [KenToonz] has decided to take on just such a project and invites viewers along for the ride. (YouTube, embedded below.)

The project is a particularly interesting one, as it involves the recreation of a robotic imitation of a human hand and arm. Thankfully, due to the hard work of dedicated individuals, blueprints of the original movie item are available online. These aren’t fully functional, per se, but give the aspiring builder a strong basis to get the look and feel right, while leaving room for modifications for those who wish to build something that moves and operates in the expected way. [KenToonz] intends to do exactly that, and contemplates the installation of various springs and other mechanisms to enable the joints to extend and retract properly.

[KenToonz] starts from the fingers, working back towards the forearm before beginning to add the various interstitial pieces that make it all work together as an assembly. The machining involved covers everything from small metal pieces of the digits to producing custom springs for the moving parts. We can’t wait to see the finished product once it’s all finished!

We’ve seen some great prop builds before, too – like this tricorder worthy of Mr Spock.

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Vintage Silvertone Cabinet Gets Bluetooth Treatment

July 30, 2018 by Steven Dufresne 7 Comments

This Bluetooth speaker is full of delightful surprises. The outer shell is an antique radio cabinet, but its practically empty interior is a combination of Dead Bug circuitry and modern BT receiver.

[PJ Allen] found the BT receiver on Groupon and decided to whip up amplifier and threshold detector circuits using only parts he already had in order to make this vintage-looking Bluetooth speaker. The cabinet is from a Silvertone Model 1955 circa 1936. Don’t worry, no antiques were harmed in the making of this hack, the cabinet was empty when he bought it.

The amplifiers, one per speaker, began life as a circuit from TI’s LM4871 datasheet. Some of the departures came about because he didn’t have the exact component values, even paralleling capacitors to get in the right range. The finished board is a delightful mix of “Dead Bug” and quasi-Manhattan style construction, “quasi” because he carved up the ground plane instead of laying pads on top of it.

Look at the front of the cabinet and you’ll see a rectangular display. Watch the video below and you’ll see that it throbs in time to the music. To do that he came up with a threshold detector circuit which started out based on a circuit from a Sharp/Optonica cassette tape deck, but to which he made improvements.

Not all cabinets come empty though. Check out this post by our own [Gregory L. Charvat] about restoring these wonderful old radios.

Continue reading “Vintage Silvertone Cabinet Gets Bluetooth Treatment” →