Bringing Modern Control To An Old Radio

The modern ham radio shack can take many forms. Some are shrines the “boat anchor” radios of old, named for their considerable weight. Others are simply a small, unassuming software-defined radio (SDR) hooked up to a laptop. Nowadays, many shacks fall somewhere in the middle. It’s not uncommon to find a sleek Icom IC-7300 sitting atop an ancient Hallicrafters SX-115 (which sounds suspiciously like the author’s setup). When a ham wants to work a digital mode such as FT-8, they will undoubtedly reach for a newer radio complete with USB (Universal Serial Bus in this case, not Upper Sideband) rig control — but what if the newest piece of equipment they have is a thirty-year-old Kenwood?

If that sounds like you, then fear not because [Steve Bossert] has you covered. He took his trusty Kenwood TS-50, a classic radio from 1993 whose most advanced feature is fuzzy logic, and upgraded it with USB (again, the serial bus) control.

When Kenwood designed the TS-50, they had computer control in mind. There’s a hidden port on the bottom of the unit which reveals a connector that mates with Kenwood’s proprietary (and expensive) set of serial control cables. Thankfully, the engineers over at Kenwood decided to use UART for PC communication, so slapping a USB port in the radio’s case isn’t as daunting as it may sound. [Steve] picked up a CP2104 USB-TTL UART Serial Adapter and wired it up to the radio’s control port. After a bit of drilling, screwing, and gluing, the radio had an upgraded (and non-proprietary!) interface compatible with the ever-popular hamlib. While this doesn’t cover all radio control functions, it gets you tuning, which is pretty important. For a fully modern radio experience, [Steve] suggests using the 8-pin mic connector along with an interface such as Rigblaster or Signalink. This adds PTT and audio signal routing.

If you want to try this for yourself, be sure to check out [Steve]’s extremely well-documented writeup. You could even take this a step further and control your TS-50 from your smartphone with this HTML5 interface we saw a few months back.

Webcam Heart Rate Monitor Brings Photoplethysmography To Your PC

It seems like within the last ten years, every other gadget to be released has some sort of heart rate monitoring capability. Most modern smartwatches can report your BPMs, and we’ve even seen some headphones with the same ability hitting the market. Most of these devices use an optical measurement method in which skin is illuminated (usually by an LED) and a sensor records changes in skin color and light absorption. This method is called Photoplethysmography (PPG), and has even been implemented (in a simple form) in smartphone apps in which the data is generated by video of your finger covering the phone camera.

The basic theory of operation here has its roots in an experiment you probably undertook as a child. Did you ever hold a flashlight up to your hand to see the light, filtered red by your blood, shine through? That’s exactly what’s happening here. One key detail that is hard to perceive when a flashlight is illuminating your entire hand, however, is that deoxygenated blood is darker in color than oxygenated blood. By observing the frequency of the light-dark color change, we can back out the heart rate.

This is exactly how [Andy Kong] approached two methods of measuring heart rate from a webcam.

Method 1: The Cover-Up

The first detection scheme [Andy] tried is what he refers to as the “phone flashlight trick”. Essentially, you cover the webcam lens entirely with your finger. Ambient light shines through your skin and produces a video stream that looks like a dark red rectangle. Though it may be imperceptible to us, the color changes ever-so-slightly as your heart beats. An FFT of the raw data gives us a heart rate that’s surprisingly accurate. [Andy] even has a live demo up that you can try for yourself (just remember to clean the smudges off your webcam afterwards).

Method 2: Remote Sensing

Now things are getting a bit more advanced. What if you don’t want to clean your webcam after each time you measure your heart rate? Well thankfully there’s a remote sensing option as well.

For this method, [Andy] is actually using OpenCV to measure the cyclical swelling and shrinking of blood vessels in your skin by measuring the color change in your face. It’s absolutely mind-blowing that this works, considering the resolution of a standard webcam. He found the most success by focusing on fleshy patches of skin right below the eyes, though he says others recommend taking a look at the forehead.

Every now and then we see something that works even though it really seems like it shouldn’t. How is a webcam sensitive enough to measure these minute changes in facial color? Why isn’t the signal uselessly noisy? This project is in good company with other neat heart rate measurement tricks we’ve seen. It’s amazing that this works at all, and even more incredible that it works so well.

Ringing In The Holidays With Self-Playing Chimes

The holiday season is here, and along with it comes Christmas music. Love them or hate them, Yuletide tunes are a simple fact of life each December. This year, [Derek Anderson] put a modern spin on a few classic melodies and listened to them via his set of self-playing chimes.

Inspired by [Derek]’s childhood Ye Merry Minstrel Caroling Christmas Bells (video), these chimes really bring the old-school Christmas decoration into the 21st century. Each chime is struck by a dedicated electromagnetically-actuated mallet, which is in turn controlled by an ESP32 running MicroPython.

Winding the electromagnets

The chimes play MIDI files, so you could, of course, play music unrelated to Christmas if you wanted to. And they even feature an OLED screen that displays what song is being played. For added flair, the entire thing is beautifully framed in black walnut, not to mention the custom-wound solenoids.

This project incorporated mechanical and electrical design, woodworking, 3D printing, programming, and song arrangement. It’s a wonder that [Derek] was able to create the entire product in the 40-80 hour time frame he estimated. (Though it looks like he had a bit of help.)

We always love to see projects like this, ones in which several disciplines get rolled together to create a beautiful finished piece.

 

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Real Hackers Videoconference In Terminal

At some point or another, many of us have tried to see how much of our digital lives could be accessed from the comfort of a terminal. We’ve tried Alpine for email, W3M for web browsing, and even watched Star Wars via telnet. But, in the increasingly socially-distant world we find ourselves in today, we find ourselves asking: what about video calling?

Okay, we weren’t asking that. But thankfully [Andy Kong] was, and saw fit to implement it when he and a friend created AsciiZOOM, a “secure, text-based videoconferencing app, accessible from the safety of your terminal.”

As you may have guessed, [Andy]’s solution replaces the conventional video stream we’re all used to with realtime animated ASCII art. The system works by capturing a video stream from a webcam, “compressing” each pixel by converting it into an ASCII character, and stuffing the entire frame into a TCP packet. Each client is connected to a server (meeting room?) which coordinates the packets, sending them back and forth appropriately.

As impressive as it is impractical, the only area in which the project lacks is in audio. [Andy] suggests using Discord to solve that, but here’s hoping we see subtitles in version 2! Will AsciiZOOM be replacing our favorite videoconferencing suite any time soon? No. Are we glad it exists? You betcha.

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How To Get Into Lost Wax Casting (with A Dash Of 3D Printing)

I’ve always thought that there are three things you can do with metal: cut it, bend it, and join it. Sure, I knew you could melt it, but that was always something that happened in big foundries- you design something and ship it off to be cast in some large angular building churning out smoke. After all, melting most metals is hard. Silver melts at 1,763 °F. Copper at 1,983 °F. Not only do you need to create an environment that can hit those temperatures, but you need to build it from materials that can withstand them.

Turns out, melting metal is not so bad. Surprisingly, I’ve found that the hardest part of the process for an engineer like myself at least, is creating the pattern to be replicated in metal. That part is pure art, but thankfully I learned that we can use technology to cheat a bit.

When I decided to take up casting earlier this year, I knew pretty much nothing about it. Before we dive into the details here, let’s go through a quick rundown to save you the first day I spent researching the process. At it’s core, here are the steps involved in lost wax, or investment, casting:

  1. Make a pattern: a wax or plastic replica of the part you’d like to create in metal
  2. Make a mold: pour plaster around the pattern, then burn out the wax to leave a hollow cavity
  3. Pour the metal: melt some metal and pour it into the cavity

I had been kicking around the idea of trying this since last fall, but didn’t really know where to begin. There seemed to be a lot of equipment involved, and I’m no sculptor, so I knew that making patterns would be a challenge. I had heard that you could 3D-print wax patterns instead of carving them by hand, but the best machine for the job is an SLA printer which is prohibitively expensive, or so I thought. Continue reading “How To Get Into Lost Wax Casting (with A Dash Of 3D Printing)”

Teensy Controller For Powerful CNCs

It seems like every year, it gets a bit easier to build your own CNC. From the Enhanced Machine Controller (EMC) project of the early 1990s to Arduinos running Grbl in the late 2000s, the open source community has moved ahead in leaps and bounds. Grbl is at its core firmware that interprets G-code and commands stepper motors, usually to move a tool head in such a way as to make something. Tons of systems have been built around it, including early Makerbot printers.

Its also spawned a plethora of other projects (the Grbl GitHib repo has 2,400 forks!), including a 32-bit flavor called grblHAL. This version is at the heart of a fantastic CNC controller board developed by [Phill Barrett]. Ditching the Arduino for a more powerful Teensy 4.1, [Phil]’s controller supports full five-axis control, variable frequency drive spindles, dust extractor control, and flood and mist coolant control. It can run at blazing stepping rates of up to 160 kHz (standard Grbl on an Arduino hits 30 kHz) and can be assembled with either a USB or Ethernet interface.

There’s no shortage of interesting Grbl-based machines out there — including a revamped Atari plotter and a three-axis rotary CNC (shameless plug for the author’s own project) but it’s always exciting to see new hardware developed that will undoubtedly find its way into the next generation of a family of projects. We can’t wait to see what comes next!

Visualizing Magnetic Memory With Core 64

For the vast majority of us, computer memory is a somewhat abstract idea. Whether you’re declaring a variable in Python or setting a register in Verilog, the data goes — somewhere — and the rest really isn’t your problem. You may have deliberately chosen the exact address to write to, but its not like you can glance at a stick of RAM and see the data. And you almost certainly can’t rewrite it by hand. (If you can do either of those things, let us know.)

These limitations must have bothered [Andy Geppert], because he set out to bring computer memory into the tangible (or at least, visible) world with his interactive memory badge Core 64. [Andy] has gone through a few different iterations, but essentially Core 64 is an 8×8 grid of woven core memory, which stores each bit via magnetic polarization, with a field of LEDs behind it that allow you to visualize what’s stored. The real beauty of this setup is that it it can be used to display 64 pixel graphics. Better yet — a bit can be rewritten by introducing a magnetic field at the wire junction. In other words, throw a magnet on a stick into the mix and you have yourself a tiny drawing tablet!

This isn’t the first time we’ve seen cool experiments with core memory, and not even the first time we’ve seen [Andy] use it to make something awesome, but it really illuminates how the technology works. Being able to not only see memory being written but to manually write to it makes it all so much realer, somehow.

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