Add A Little Quindar To Your Comms For That Apollo-Era Sound

April 30, 2023 by 9 Comments

If there’s one thing that ties together all the media coming out of the Apollo era, it’s probably the iconic Quindar tones. These quarter-second beeps served as control tones for the globe-spanning communications network needed to talk to the Apollo astronauts, and any attempt to recreate the Apollo-era sound would be glaringly wrong without them. And that’s why [CuriousMarc] whipped up this Quindar tone system.

The video below starts with a detailed treatment of what Quindar tones are and why they were used, a topic we’ve covered ourselves in the past. To recap, Quindar tones are a form of in-band signaling, with a 2,525-Hz pure sine wave intro tone that signaled the transmitters connected to Mission Control in Houston over leased telephone lines to key up. The 2,475-Hz outro tone turned off the transmitters and connected the line to the receivers.

To recreate the sound quality of the original circuitry, and to keep in the retro vibe, [Marc]’s Quindar homage avoided digital circuitry as much as possible, opting instead to generate the two tones with an XR-2206 function generator chip. The chip can rapidly switch back and forth between two frequencies, making it perfect for FSK applications or, in this case, reproducing the two slightly different tones. [Marc] added a dual mono-stable multi-vibrator to pulse the tone, giving the 250-ms pulse, and an audio gate, which uses a MOSFET to switch the tone into an audio stream. All this got soldered up to a piece of perf board and stuffed in the base of a cheap intercom microphone, which while not period accurate still has a cool retro look — and now, a retro sound, too.

Hats off to [CuriousMarc] and his merry band for probing the mysteries of Apollo-era comms and keeping the accomplishments of all those engineers alive. The methods they used are still relevant after all these years, and there seems to be no end to what we can learn from them.

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When Your Smart Light Switches Stop Working, Build Your Own

April 30, 2023 by 14 Comments

If you want smart light switches in your house, you can buy from any one of hundreds of manufacturers. [Brian Boyle] had kitted out his home with TP Link devices, but after a few years of use, he found they all suddenly failed within a few months of each other. Decrying the state of things, he set about building his own instead.

[Brian]’s switches use the ESP32 for its handy in-built WiFi hardware. His aim was to produce smart switches that would fit neatly into standard “Decor” style switch boxes. The design uses two PCBs. One is charged with handling the mains power side of things. It carries an SPDT relay for switching AC power, and a DC power supply to run the ESP32 itself. The controller board holds the microcontroller, a Neopixel as a status indicator, and a pair of buttons — one for switching the lights on and off, the other for resetting to default settings. The physical housing is 3D printed, and looks great with the glowing status indicator in the middle of the switch.

[Brian]’s switches are triggerable via MQTT, a web interface, and the physical button onboard the device itself. Having built the devices on his own, he’ll be well-placed to troubleshoot any usability or reliability issues that crop up in the future. That’s a lot more than we can say about most smart devices on the market!

USB Borescope Lets Doctors Hone Intubation Skills On The Cheap

April 30, 2023 by 8 Comments

One of the most critical skills in emergency medicine is airway management. Without a patent airway, a patient has about four minutes to live, so doctors and paramedics put a huge amount of effort into honing their intubation skills. They have to be able to insert an endotracheal tube quickly and efficiently, without damaging sensitive structures like the vocal cords. It’s a tricky skill to master without a ton of practice.

The perfect tool to practice these skills is a video laryngoscope, but these are wildly expensive and reserved for clinical use. Luckily, with a little ingenuity and a cheap USB borescope, [Dr. Adam Blumenberg] and [Dr. Erin Falk] were able to come up with this low-cost video-assisted laryngoscopy setup to reach as many students as possible. The idea is to use a single-use laryngoscope blade, which replicates the usual tool used to visualize the patient’s vocal cords. The blade is made from clear plastic, which makes it perfect for the application. The borescope is passed through an opening in the blade and affixed to it with adhesives. A little Dremel work might be necessary to get the optical axes of the blade and the camera to line up; failing that, there’s always the option to disassemble the camera to get a better angle.

The chief advantage of this setup, aside from being cheap, is that it’s something that it’s not intended to be used on patients. Along with an airway manikin, the tricked-out borescope can sit in a conference room waiting for students to have a go. Using a large screen allows the whole group to watch the delicate procedure and learn from the mistakes of others. It may not be as detailed a simulation environment as some, but “blade time” is really what counts here.

RP2040 Gets Intellikeys Keyboard Up And Running

April 29, 2023 by 7 Comments

The Spectronic Intellikeys was an innovative keyboard-like accessibility device that used special plastic overlays that change its functionality. While a USB version of the accessible keyboard exists, it doesn’t work like a normal HID device, so it’s not plug and play as you might expect. It’s also no longer in production or supported by the manufacturer. Where industry falls down, the community steps in, right? To that end, Adafruit has built a tool for interfacing with these useful accessibility devices.

The key is the way the Intellikeys was intended to work with a computer. It was designed to download its firmware from the host machine, using special drivers that are only compatible with certain versions of Windows. That means you can’t use it with iPads or Chromebooks, for example.

To get around this, Adafruit used an RP2040 Feather configured as a USB host to talk to the Intellikeys. It queries the device, determines which overlay it currently has installed, and provides it the necessary firmware. On the other end, the Feather enumerates as a regular USB HID device. That allows it to work with a wide variety of tablets, computers, and even smartphones.

If you’ve got an Intellikeys USB device and miss using it, this could be just the thing you need. Meanwhile, you can check out some of the other interesting keyboard designs we’ve featured over the years.

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Don’t Let The Baluns Float Over Your Head

April 29, 2023 by 5 Comments

Most ham radio operators will build an antenna of some sort when they first start listening or transmitting, whether it’s a simple dipole, a beam antenna like a Yagi, or even just a random wire vertical antenna. All of these will need to be connected feedline of some sort, and in the likely event you reach for some 50-ohm coax cable you’ll also need a balun to reduce noise or unwanted radiation. Don’t be afraid of extra expenses when getting into this hobby, though, as [W6NBC] demonstrates how to construct an “ugly balun” out of the coax wire itself (PDF).

The main purpose of a balun, a contraction of “balanced-unbalanced” is to convert an unbalanced transmission line to a balanced one. However, as [W6NBC] explains, this explanation obscures much of what baluns are actually doing. In reality, they take a three-wire system (the coax) and convert it to a two-wire system (the antenna), which keeps all of the electrical noise and current on the shield wire of the coax from interfering with the desirable RF on the interior of the coax.

This might seem somewhat confusing on the surface, as coax wires only have a center conductor and a shield wire, but thanks to the skin effect which drives currents to the outside of the conductor, the shield wire effectively becomes two conductors when taking into account its inner and outer surfaces. At these high frequencies the balun is acting as a choke which keeps these two high-frequency conductors separate from one another, and keeps all the noise on the outside of the shield wire and out of the transmitter or receiver.

Granted, the world of high-frequency radio circuits can get quite complex and counter-intuitive and, as we’ve shown before, can behave quite unexpectedly when compared to DC or even mains-frequency AC. But a proper understanding of baluns and other types of transformers and the ways they interact with RF can be a powerful tool to have. We’eve even seen other hams use specialty transformers like these to make antennas out of random lengths and shapes of wire.

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Hackaday Prize 2023: Tiny RC Aircraft Built Using Foam And ESP12

April 29, 2023 by 13 Comments

Once upon a time, a radio controlled plane was a hefty and complex thing. They required small nitro engines, support equipment, and relatively heavy RC electronics. Times have changed since then, as this lightweight RC build from [Ravi Butani] demonstrates.

The body of the plane is lightweight foam, and can be assembled in two ways. There’s a relatively conventional layout, using a main wing, tailplane, and rudder, or a pusher model with the main wing at the rear and a canard up front. The open hardware electronics package, which [Ravi] calls VIMANA, consists of an ESP12 module with a pair of MOSFETs to act as two independent motor drivers — allowing the plane to be flown and steered with differential thrust.

For more advanced flight control, it can also command a pair of servos to control ailerons, a rudder, canards, or elevons, depending on configuration. There’s also potential to install an IMU to set the plane up with flight stabilization routines.

Thanks to the low-cost of the VIMANA board, [Ravi] hopes it can be used in STEM education programs. He notes that it’s not limited just to aircraft, and could be used for other motorized projects such as boats and cars. We’ve featured an early version of his work before, but the project has come a long way since then.

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The World’s First Agricultural Right To Repair Law

April 29, 2023 by 29 Comments

Long time readers will know that occasionally we mix up our usual subject matter with a dash of farm equipment. Usually the yellow and green variants that come from John Deere, as the agricultural manufacturer has become the poster child for all that is wrong in the fight for the right to repair. An old Deere is worth more than a nearly new one in many places, because for several years now their models have had all their parts locked down by DRM technologies such that only their own fitters can replace them. Now after a long legal fight involving many parties, the repair and parts company iFixit sound justifiably pleased as they announce the world’s first agricultural right to repair law being passed in the US state of Colorado. (Nitter)

This may sound like a small victory, and it will no doubt be followed by further rearguard actions from the industry as similar laws are tabled in other states. But in fact as we read it, with this law in place the game is de facto up for the tractor makers. Once they are required to release any access codes for the Coloradans those same codes will by extension be available to any other farmers, and though we’re guessing they won’t do this, they would be best advised to give up on the whole DRM idea and concentrate instead on making better tractors to fix their by-now-damaged brands.

It’s exciting news for everybody as it proves that right-to-repair legislation is possible, however since this applies only to agricultural machinery the battle is by no means over. Only when all machines and devices have the same protection can we truly be said to have achieved the right to repair.

We’ve reported on this story for a long time, here’s a previous piece of legislation tried in another state.