Arduino RC Transmitter For Homebrew Projects

The field of radio control has benefited much from the onward march of technology. Where a basic 2-channel setup would once have cost hundreds of dollars, it’s now possible to get a high-end 2.4GHz 9-channel rig for well under $100, shipped to your door. However, the vast majority of these systems are closed-source and built for purpose. Sometimes, there are benefits to doing things your own way, and that’s precisely what this project does.

At its heart, it’s a simple combination. An Arduino Pro Mini talks to a NRF24L01 which handles the wireless communication. At that point, it’s up to you – throw in as few or as many controls as you like. For this build, [HowToMechatronics] has gone with a twin-stick setup, with a pair of potentiometers and twin toggle switches to round out the options.

The build comes in handy, as it’s possible to program in whatever features you may need for a given project. [HowToMechatronics] has used it to control a hexapod robot, among other projects. It’s a build that shows that with cheap and readily available parts, it’s possible to whip up a custom solution to suit your needs.

If this topic interests you.it’s worth saying that even those closed source radio control products can sometimes be hacked.

[Thanks to Baldpower for the tip!]

No Moving Parts: Phased Array Antennas Move While Standing Still

If you watch old science fiction or military movies — or if you were alive back in the 1960s — you probably know the cliche for a radar antenna is a spinning dish. Although the very first radar antennas were made from wire, as radar sets moved higher in frequency, antennas got smaller and rotating them meant you could “look” in different directions. When most people got their TV with an antenna, rotating those were pretty common, too. But these days you don’t see many moving antennas. Why? Because antennas these days move electrically rather than physically using multiple antennas in a phased array. These electronically scanned phased array antennas are the subject of Hunter Scott’s talk at 2018’s Supercon. Didn’t make it? No problem,  you can watch the video below.

While this seems like new technology, it actually dates back to 1905. Karl Braun fed the output of a transmitter to three monopoles set up as a triangle. One antenna had a 90 degree phase shift. The two in-phase antennas caused a stronger signal in one direction, while the out-of-phase antenna canceled most of the signal and the resulting aggregate was a unidirectional beam. By changing the antenna fed with the delay, the beam could rotate in three 120 degree steps.

Today phased arrays are in all sorts of radio equipment from broadcast radio transmitters to WiFi routers and 5G phones. The technique even has uses in optics and acoustics.

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Morse Code Keyboard 1939 Style!

If you want to learn Morse code and you don’t have a teacher, you’d probably just head over to a website or download a phone app. Before that, you probably bought a cassette tape or a phonograph record. But how did you learn Morse if you didn’t have any of that and didn’t know anyone who could send you practice? Sure, you could listen to the radio, but in 1939 that might be difficult, especially to find people sending slow enough for you to copy.

Wireless World for August 3rd, 1939, has the answer in an article by [A. R. Knipe] on page 109. While you probably wouldn’t use it today, it is a great example of how ingenious you can be when you don’t have an Arduino and all the other accoutrements we take for granted today.

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All About Ham Satellites

How hard is it to build a ground station to communicate with people via a satellite? Probably not as hard as you think. [Modern Ham] has a new video that shows just how easy it can be. It turns out that a cheap Chinese radio is all you need on the radio side. You do, however, benefit from having a bit of an antenna.

It isn’t unusual for people interested in technology to also be interested in space. So it isn’t surprising that many ham radio operators have tied space into the hobby. Some do radio astronomy, others bounce signals off the moon or meteors. Still others have launched satellites, though perhaps that’s not totally accurate since as far as we know all ham radio satellites have hitched rides on commercial rockets rather than being launched by hams themselves. Still, designing and operating a ham radio station in space is no small feat, but it has been done many times with each generation of satellite becoming more and more sophisticated.

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Google Assistant, Now Available On Ham Radio

Depending on who you talk to, Google Assistant is either a tool capable of quickly and clearly answering audio queries in natural langauge, or a noisier and less useful version of Wolfram Alpha. [William Franzin] decided it would be particularly cool to make the service available over ham radio – and that’s exactly what he did.

[William] got the idea for this project after first playing with the Internet Radio Linking Project, a system which uses VoIP technologies to link radio networks over the internet. Already having an IRLP node, it seemed only natural to make it into a gateway to the wider internet through integration with Google Assistant. Early work involved activating the assistant via DTMF tones, but [William] didn’t stop there – through the use of Picovoice, it became possible to use the system with the custom wakeword “Bumblebee”.

[William]’s project could prove particularly useful for when he’s out of cell coverage, but needs a little information like a weather report or a piece of trivia to settle an argument round the campfire. Additionally, it’s even possible to control the IRLP node through voice commands, too.

If you’re just getting started with ham radio, check out this build to get you started for under $100. Video after the break.

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Superheterodyne Radios Explained

The general public thinks there is one thing called a radio. Sure, they know there are radios that pick up different channels, but other than that, one radio is pretty much like the other. But if you are involved in electronics, you probably know there are lots of ways a radio can work internally. A crystal set is very different from an FM stereo, and that’s different still from a communications receiver. We’d say there are several common architectures for receivers and one of the most common is the superheterodyne. But what does that mean exactly? [Technology Connection] has a casual explanation video that discusses how a superhet works and why it is important. You can see the video, below.

Engineering has always been about building on abstractions. This is especially true now when you can get an IC or module that does most of what you want it to do. But even without those, you would hardly start an electronics project by mining copper wire, refining it, and drawing your own wire. You probably don’t make many of your own resistors and capacitors, neither do you start your design at the fundamental electronic equations. But there’s one abstraction we often forget about: architecture. If you are designing a receiver, you probably don’t try to solve the problem of radio reception; instead you pick an architecture that is proven and design to that.

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Radio Gets Ridiculous

There were plenty of great talks at this year’s Supercon, but we really liked the title of Dominic Spill’s talk: Ridiculous Radios. Let’s face it, it is one thing to make a radio or a computer or a drone the way you are supposed to. It is another thing altogether to make one out of things you shouldn’t be using. That’s [Dominic’s] approach. In a quick 30 minutes, he shows you two receivers and two transmitters. What makes them ridiculous? Consider one of the receivers. It is a software defined radio (SDR). How many bits should an SDR have? How about one bit? Ridiculous? Then you are getting the idea.

Dominic is pretty adept at taking a normal microcontroller and bending it to do strange RF things and the results are really entertaining. The breadboard SDR, for example, is a microcontroller with three components: an antenna, a diode, and a resistor. That’s it. If you missed the talk at Supercon, you can see the newly published video below, along with more highlights from Dominic’s talk.

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