transmitter

84 Articles

Supercon 2024: How To Track Down Radio Transmissions

June 3, 2025 by 10 Comments

You turn the dial on your radio, and hear a powerful source of interference crackle in over the baseline noise. You’re interested as to where it might be coming from. You’re receiving it well, and the signal strength is strong, but is that because it’s close or just particularly powerful? What could it be? How would you even go about tracking it down?

When it comes to hunting down radio transmissions, Justin McAllister and Nick Foster have a great deal of experience in this regard. They came down to the 2024 Hackaday Superconference to show us how it’s done.

Continue reading “Supercon 2024: How To Track Down Radio Transmissions” →

NES Zapper Becomes Telephone

May 25, 2025 by 9 Comments

Although there was a time in the 80s (and early 90s for fans of the SuperScope) where light guns were immensely popular, with games like DuckHunt cultural touchstones, their time in the video game world has largely come to an end. We might occasionally pick up a Zapper for the NES and play this classic out of nostalgia, but plenty of people are looking for other things that these unique video game controllers can do instead. [Nick] has turned one of his old NES peripherals into a wireless phone.

The way the original Zapper worked was by looking for a certain pattern of pixels that displayed for a fraction of a second whenever the trigger was pulled. Bypassing the anti-cheat mechanism that looks only for qualities of light coming from CRT screens of the day effectively turns the light gun into an analog light sensor which is used for receiving the audio from the phone’s base station via a laser. Of course there were no microphones present within the original hardware so one is added, wiring its output to another laser that communicates to the base station. With the light gun pointed directly at this base station, audio is communicated back and forth by varying the strengths of these small lasers and listening to them on the other end with photodiodes.

[Nick] does point out that this isn’t a great phone, largely because it needs to be pointed exactly at the right spot to work at all, although we do agree that it’s an interesting project that demonstrates what the original hardware could do with a few of its limitations removed. There are a few other ways of bringing these devices into the modern world, with one of our favorites being this laser pointer with additional hardware from a Wiimote that could also function as a mouse.

Continue reading “NES Zapper Becomes Telephone” →

Brush Up On Your Trade Craft With This Tiny FM Bug

April 11, 2025 by 19 Comments

Would-be spooks and spies, take note: this one-transistor FM transmitter is a circuit you might want to keep in mind for your bugging needs. True, field agents aren’t likely to need to build their own equipment, but how cool a spy would you be if you could?

Luckily, you won’t need too many parts to recreate [Ciprian (YO6DXE)]’s project, most of which could be found in a decently stocked junk bin, or even harvested from e-waste. On the downside, the circuit is pretty fussy, with even minor component value changes causing a major change in center frequency. [Ciprian] had to do a lot of fiddling to get the frequency in the FM band, particularly with the inductor in the LC tank circuit. Even dropping battery voltage shifted the frequency significantly, which required a zener diode to address.

[Ciprian] ran a few tests and managed to get solid copy out to 80 meters range, which is pretty impressive for such a limited circuit. The harmonics, which extend up into the ham bands and possibly beyond, are a bit of a problem; while those could be addressed with a low-pass filter, in practical terms, the power of this little fellow is probably low enough to keep you from getting into serious trouble. Still, it’s best not to push your luck.

While you’re trying your hand at one-transistor circuits, you might want to try [Ciprian]’s one-transistor CW transceiver next.

Continue reading “Brush Up On Your Trade Craft With This Tiny FM Bug” →

Lockdown Remote Control Project Is Free And Open

April 4, 2025 by 8 Comments

If you flew or drove anything remote controlled until the last few years, chances are very good that you’d be using some faceless corporation’s equipment and radio protocols. But recently, open-source options have taken over the market, at least among the enthusiast core who are into squeezing every last bit of performance out of their gear. So why not take it one step further and roll your own complete system?

Apparently, that’s what [Malcolm Messiter] was thinking when, during the COVID lockdowns, he started his own RC project that he’s calling LockDownRadioControl. The result covers the entire stack, from the protocol to the transmitter and receiver hardware, even to the software that runs it all. The 3D-printed remote sports a Teensy 4.1 and off-the-shelf radio modules on the inside, and premium FrSky hardware on the outside. He’s even got an extensive folder of sound effects that the controller can play to alert you. It’s very complete. Heck, the transmitter even has a game of Pong implemented so that you can keep yourself amused when it’s too rainy to go flying.

Of course, as we alluded to in the beginning, there is a healthy commercial infrastructure and community around other open-source RC projects, namely ExpressLRS and OpenTX, and you can buy gear that runs those software straight out of the box, but it never hurts to have alternatives. And nothing is easier to customize and start hacking on than something you built yourself, so maybe [Malcolm]’s full-stack RC solution is right for you? Either way, it’s certainly impressive for a lockdown project, and evidence of time well spent.

Thanks [Malcolm] for sending that one in!

FM Transmitter Remotely Controlled Via ESP32

October 18, 2024 by 14 Comments

Imagine you’ve got an FM transmitter located some place. Wouldn’t it be mighty convenient if you could control that transmitter remotely? That way, you wouldn’t have to physically attend to it every time you had to change some minor parameters! To that end, [Ricardo Lima Caratti] built a rig to do just that.

The build is based around the QN8066—a digital FM transceiver built into a single chip. It’s capable of transmitting and receiving anywhere from 60 MHz to 108 MHz, covering pretty much all global FM stereo radio bands. [Ricardo] paired this chip with an ESP32 for command and control. The ESP32 hosts an HTTP server, allowing the administration of the FM transmitter via a web browser. Parameters like the frequency, audio transmission mode, and Radio Data Service (RDS) information can be controlled in this manner.

It’s a pretty neat little build, and [Ricardo] demonstrates it on video with the radio transmitting some field day content. We’ve seen some other nifty FM transmitters over the years, too. Video after the break.

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Be Your Own DJ With QN8066 And An Arduino Library

August 10, 2024 by 5 Comments

The QN8066 is a fun little FM transmitter chip. It covers the full FM broadcast band and has built-in DSP. You would find this sort of part in car cell phone adapters before every vehicle included Bluetooth or an AUX port.  [Ricardo] has created an Arduino library to bring the QN8066 to the masses.

The chip is rather easy to use – control is handled with a common I2C interface. All the complex parts – Phase Locked Loop (PLL), RF front end, power management, and audio processing are all hidden inside. [Ricardo’s] library makes it even easier to use. One of the awesome features of the 8066 is the fact that it handles Radio Data System (RDS). RDS is the subcarrier datastream that allows FM stations to inject information like song title and artist into the signal. The data is then displayed on your radio screen.

You can find the source to [Ricardo’s] library on GitHub. Using it is as simple as picking it up from the Arduino IDE.

If you are looking for an RDS-enabled radio to test out your QN8066 design, you wouldn’t do too bad with this Gameboy cartridge receiver.

Click through the break for a video from [Ricardo] explaining his QN8066 design. Continue reading “Be Your Own DJ With QN8066 And An Arduino Library” →

A Super-Simple Standalone WSPR Beacon

June 14, 2024 by 26 Comments

We’ve said it before and we’ll say it again: being able to build your own radios is the best thing about being an amateur radio operator. Especially low-power transmitters; there’s just something about having the know-how to put something on the air that’ll reach across the planet on a power budget measured in milliwatts.

This standalone WSPR beacon is a perfect example. If you haven’t been following along, WSPR stands for “weak-signal propagation reporter,” and it’s a digital mode geared for exploring propagation that uses special DSP algorithms to decode signals that are far, far down into the weeds; signal-to-noise ratios of -28 dBm are possible with WSPR.

Because of the digital nature of WSPR encoding and the low-power nature of the mode, [IgrikXD] chose to build a standalone WSPR beacon around an ATMega328. The indispensable Si5351 programmable clock generator forms the RF oscillator, the output of which is amplified by a single JFET transistor. Because timing is everything in the WSPR protocol, the beacon also sports a GPS receiver, ensuring that signals are sent only and exactly on the even-numbered minutes. This is a nice touch and one that our similar but simpler WSPR beacon lacked.

This beacon had us beat on performance, too. [IgrikXD] managed to hit Texas and Colorado from the edge of the North Sea on several bands, which isn’t too shabby at all with a fraction of a watt.

Thanks to [STR-Alorman] for the tip.

[via r/amateurradio]