A Tube Theremin, Just Like Grandpa Leon Used To Make

Next year we’re arguably coming up on the centennial of electronic music, depending on whether you count the invention or the patent for the theremin its creation. Either way, this observation is early, so start arguing about it now. If you want to celebrate the century of the theremin, how about you do it just like grandpa Leon and build one out of tubes? That’s what this crowdfunding campaign is all about. It’s a theremin, and it’s made out of tubes.

Theremins are a dime a dozen around these parts, and yes, if you walk into a Guitar Center you can walk out the door with one. They’re pretty common. But being almost a hundred years old, the first theremin wasn’t made made with only silicon, this one had some dioxide thrown in. The first theremin was a tube device, which we all know has a warmer sound when connected to oxygen free cables in an oxygen free room. In any event, messing around with tubes is fun, so here’s a tube theremin.

The circuit for this theremin is constructed around two EF95 tubes and two ECF80 tubes with a heater voltage of 12 V, with 40 V used as the the rest of the circuitry. Unlike virtually every other crowdfunding campaign we’ve ever seen, there are pages of documentation, written down in text, with actual words, and no ominous clapping ukulele glockenspiel hipster music. It’s in German (Google Translatrix with the save) but we’ll take what we can get. It’s really great to see the development of this theremin, and now we’re wondering where we too can get a breadboard that’s just a piece of copper being used as a ground plane.

A New Digital Mode For Radio Amateurs

There used to be a time when amateur radio was a fairly static pursuit. There was a lot of fascination to be had with building radios, but what you did with them remained constant year on year. Morse code was sent by hand with a key, voice was on FM or SSB with a few old-timers using AM, and you’d hear the warbling tones of RTTY traffic generated by mechanical teletypes.

By contrast the radio amateur of today lives in a fast-paced world of ever-evolving digital modes, in which much of the excitement comes in pushing the boundaries of what is possible when a radio is connected to a computer. A new contender in one part of the hobby has come our way from [Guillaume, F4HDK], in the form of his NPR, or New Packet Radio mode.

NPR is intended to bring high bandwidth IP networking to radio amateurs in the 70 cm band, and it does this rather cleverly with a modem that contains a single-chip FSK transceiver intended for use in licence-free ISM band applications. There is an Ethernet module and an Mbed microcontroller board on a custom PCB, which when assembled produces a few hundred milliwatts of RF that can be fed to an off-the-shelf DMR power amplifier.

Each network is configured around a master node intended to use an omnidirectional antenna, to which individual nodes connect. Time-division multiplexing is enforced by the master so there should be no collisions, and this coupled with the relatively wide radio bandwidth of the ISM transceiver gives the system a high usable data bandwidth.

Whether or not the mode is taken up and becomes a success depends upon the will of individual radio amateurs. But it does hold the interesting feature of relying upon relatively inexpensive parts, so the barrier to entry is lower than it might be otherwise. If you are wondering where you might have seen [F4HDK] before, we’ve previously brought you his FPGA computer.

Hackaday Links: March 31, 2019

You can now make flexible circuit boards of unlimited length. Trackwise was contracted out for making a wiring harness for the wing of a UAV and managed to ship a 26 meter long flexible printed circuit board. This is an interesting application of the technology — UAVs are very weight sensitive and wiring harnesses are heavy. Wings are straight, but they flex, and you need wires going from tip to tip. Flex circuits do all of this well, but first you need a technology that allows you to manufacture circuits that are as long as a wing. This is apparently something called ‘reel-to-reel’ technology, or some variant of continuous production. Either way, it’s cool, and we’re wondering what else this kind of circuit enables.

You may have noticed a few odd-shaped buildings going up in the last few years. These are buildings designed for indoor skydiving. Two went up around DC in the last year or so. What if you didn’t need a building? What if you could make an outdoor, vertical wind tunnel? Here you go, it’s the Aerodium Peryton.

KiCon, the first and largest gathering of hardware developers using KiCad, is happening April 26th in Chicago.

If KiCad isn’t your thing, PyCon is in Cleveland May 1-9. It couldn’t come at a better time: after losing LeBron, the Cleveland economy has plummeted 90%. Cleveland needs an industry now, and tech conferences are where it’s at. Go Browns.

For one reason or another, a few tech blogs wrote about a product on Tindie last week. It’s the SnapOnAir Raspberry Pi Zero PCB. This turns a Raspberry Pi Zero into a tiny, battery-powered handheld computer with a keyboard and display. This is just a PCB, and you’ll need to bring your own switches, display, and other various modules, but it is a compact device and if you need a small, handheld Linux¬†thing, this is a pretty good solution.

Oh noes April Fools is tomorrow, which means the Internet will be terrible. Tip ‘o the hat to Redbox, though: they were the only one that sent out a press release to their waste of electrons by last Friday.

 

Build Your Own Metal Roller

Metal fabrication is a useful skill to have. There’s plenty you can achieve in your workshop at home, given the right tools. There’s lathes for turning, mills for milling, and bandsaws and dropsaws for chopping it all to pieces. But what do you do if you need to make hoops and bends and round sections? You build a metal roller, of course – and that’s precisely what [James Bruton] did.

The main body of the tool is built out of box section, chosen largely as it’s what [James] had lying around. Bearings are of the familiar pillow block variety, with 20 mm bright steel serving as the rollers due to its better tolerance than mild steel stock. Set screws hold the shafts in place to avoid everything sliding around the place. A 10-ton bottle jack then provides the force to gently bend the workpiece as it passes through the rollers.

Initial tests were positive, with the roller producing smooth curves in 4 mm thick steel bar. There were some issues with runout, which were easily fixed with some attention to the parallelism of the shafts. It’s a tidy build, and can serve as a basis for further upgrades in future if necessary.

We’ve seen DIY roll benders before, too. Video after the break.

Continue reading “Build Your Own Metal Roller”

A Weather Station Fit For A PDP-11

The Digital Equipment Corp. PDP-11/70 is a masterpiece of Cold War-era industrial design. This microcomputer was the size of one or two modern server racks depending on configuration, and the front panel, loaded up with blinkenlights, was clad in a beautiful rose and magenta color scheme. The switches — the ones you used to toggle bits in memory — were actually custom designed covers made to match the shape of the completely unnecessary bezel. The aesthetic of the 11/70 is the intersection of baroque and modernism on the design Venn diagram.

[Oscar Vermeulen] built a miniature version of the PDP-11/70 that houses a Raspberry Pi, and [rricharz] has been hard at work bringing an original copy of BSD to this system. The first great project to come out of this effort? It’s a weather station, and it’s exactly as cool as you think it is.

A bit of ground work went into this build, including getting a historical Unix system up and running, in this case 2.11 BSD. Armed with a Pi and the PiDP-11/70 front panel, [rricharz] had a complete BSD system up and running, and with cool-retro-term, the interface looked the part. Doing something useful was another question entirely, but the Pi in the PiDP had some GPIOs free, so this ancient machine got an I2C temperature and pressure sensor.

The completed build is basically just a breadboard, a tiny diagnostic OLED, and a python script that grabs the data and sends it over to the sim. This is pressure and temperature data shoved into an emulation of a Tektronix 4010 terminal. It’s marginally useful work done by an ancient BSD system wrapped in an emulation on a Raspberry Pi. It doesn’t get better than that.

Squeezebox Comes To The ESP

Streaming music may now come from somewhere in the cloud to an app on your phone and be sent to the client built in to almost every entertainment device you own, but there was a time when the bleeding edge lay in dedicated streaming device that connected to your existing set-up. One of the players in this market was Logitech with their Squeezebox line of products, and while the original hardware may have been discontinued it remains very much alive among its dedicated userbase due to the free nature of the Logitech Media Server software and implementations of the slimproto streaming protocol in players. Now you can create a network player on about as cheap hardware as it is possible to find, because [Bgiraut] has produced a client for the ESP32 and ESP8266.

The software can be found on GitHub, and comes with the warning that it’s an early proof-of-concept rather than a polished release. It has two options for playback that both require a little bit of extra hardware, an I2S DAC for uncompressed streams or a VS1053 codec module for compressed ones, but neither of those need be expensive.

You can find Logitech Media Server from its download page, and give this device a try. Meanwhile we’ve covered many Squeezebox implementations, including ones on the Raspberry Pi, and the PogoPlug.

Thanks [joyofdivisions] for the tip.

ROS Gets Quick Sensor Debugging In The Terminal

Sensors are critical in robotics. A robot relies on its sensor package to perform its programmed duties. If sensors are damaged or non-functional, the robot can perform unpredictably, or even fail entirely. [Dheera Venkatraman] has been working to make debugging sensor issues easier with the rosshow package for Robot Operating System.

Normally, if you want to be certain a camera feed is working on a robot, normally you’d have to connect a monitor and other peripherals, check manually, then put everything away again when you’re finished. [Dheera] considered this was altogether too much of a pain for basic sensor checks.

Instead, rosshow uses the power of SSH to speed things along. Log in to the robot, fire off a few command line instructions, and rosshow will start displaying sensor data in the terminal on your remote machine. It’s achieved through the use of Unicode Braille art in the terminal.¬† Sure, you won’t get a full-resolution feed from your high-definition camera, and the display from the laser scanner isn’t exactly perfect. But it’s enough to provide an instant verification that sensors are connected and working, and will speed up those routine is-it-connected checks by an order of magnitude.

Robot Operating System is a particularly useful platform if you’re thinking about the software platform for your next build. If you do put something together, be sure to let us know.