radio

571 Articles

DIY SI5351 Radio Tunes In SW, MW, And More

July 2, 2026 by 11 Comments

There are plenty of radios you can buy that pick up MW and SW bands if that’s what you’re into. Or, you can follow [mircemk]’s example, and whip one up yourself instead.

The build employs an ESP32 as the brains of the operation. It’s hooked up to a rotary encoder and a small colour TFT screen, which displays an old-school style tuning dial for choosing the desired frequency. This setup is paired with an Si5351—a capable clock generator chip that can deliver just about any frequency from <8KHz up to 150+ MHz on command. There’s naturally a bunch of supporting analog hardware for the radio end of things, plus a NE612 mixer IC and a PAM8403 class D audio amplifier board, hooked up to a small 0.25W speaker for audio output. [mircemk] has set up the rig to act as a simple radio set, or, with the flick of a switch, it can be configured for SDR use with an attached computer.

It’s a handsome build, and one that likely proves a pleasant way to browse the MW and SW bands on a rainy afternoon. We’ve looked at other hardware in this category before, too. Video after the break.

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Mechanical Stability For Your Coils

June 11, 2026 by 8 Comments

If you work with radio, the chances are that before too long you’ll be winding an inductor. At radio frequencies these won’t be big chunky transformer style chokes, but often air-cored affairs supported by their own rigidity. As grizzled old radio amateurs will tell you though, relying on such a coil for stability is a fool’s errand. It will shift inductance from the slightest movement, thermal expansion, or even sound. Luckily [SolderSmoke] is here to remind us of the trusty fix, in the form of Q-dope, or a polystyrene solution that dries to form a rigid low-dielectric coating.

Where this is being written it wasn’t on the market so it was more usual to use nail lacquer, but reading the piece it seems American hams swore by the stuff. That’s in the past tense because it seems it’s no longer on the market. Even there though help is at hand, because dissolving packaging polystyrene in solvent yields an acceptable substitute. There’s even an 11-year-old how-to video linked from the SolderSmoke post, should you fancy making some of your own. We suggest you proceed with caution though, polymers dissolved in solvents sounds a lot like home-made napalm, and probably puts out fumes you don’t want to breathe.

Meanwhile should you fancy experiments of your own with inductors, we’ve got you covered.

Analog Video From An 8-Bit Microcontroller

March 21, 2026 by 24 Comments

Although the CRT has largely disappeared from our everyday lives, there was a decades-long timeframe when this was effectively the only display available. It’s an analog display for an analog world, and now that almost everything electronic is digital, these amazing pieces of technology are largely relegated to retro gaming and a few other niche uses. [Maurycy] has a unique CRT that’s small enough to fit in a handheld television, but since there aren’t analog TV stations anymore, he decided to build his own with nothing but an 8-bit microcontroller and a few other small parts.

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Restoring The Soul Of A 1940s Radio

February 4, 2026 by 13 Comments

Although we do often see projects that take antiques and replace some or all of their components with modern equipment, we can also sympathize with the view that (when possible and practical) certain antique electronics should be restored rather than gutted. [David] has this inclination for his 1948 GE radio, but there are a few issues with it that prevented a complete, period-correct restoration.

The main (pun intended) issue at the start of this project was safety. The original radio had a chassis that was just as likely as not to become energized, with the only protection being the plastic housing. [David] set up an isolation transformer with a modern polarized power cable to help solve this issue, and then got to work replacing ancient capacitors. With a few other minor issues squared away this is all it took to get the radio working to receive AM radio, and he also was able to make a small modification to allow the radio to accept audio via a 3.5mm jack as well.

However, [David] also has the view that a period-correct AM transmission should accompany this radio as well and set about with the second bit of this project. It’s an adaptation of a project called FieldStation42 originally meant to replicate the experience of cable TV, but [Shane], the project’s creator, helped [David] get it set up for audio as well. A notable feature of this system is that when the user tunes away from one station, it isn’t simply paused, but instead allowed to continue playing as if real time is passing in the simulated radio world.

Although there are a few modern conveniences here for safety and for period-correct immersion, we think this project really hits the nail on the head for preserving everything possible while not rolling the dice with 40s-era safety standards. There’s also a GitHub page with some more info that [David] hopes to add to in the near future. This restoration of a radio only one year newer has a similar feel, and there are also guides for a more broad category of radio restorations as well.

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The Cutting Truth About Variable Capacitors

January 1, 2026 by 10 Comments

If you’ve seen a big air-variable capacitor, you may have noticed that some of the plates may have slots cut into them. Why? [Mr Carlson] has the answer in the video below. The short answer: you can bend the tabs formed by the slots to increase or decrease the capacitance by tiny amounts for the purpose of tuning.

For example, if you have a radio receiver with a dial, you can adjust the capacitor to make certain spots on the dial have an exact frequency. Obviously, you can only adjust in bands depending on how many slots are in the capacitor. Sometimes the adjustments aren’t setting the oscillator’s frequency. For example, the Delco radio he shows uses the capacitor to peak the tuning at the specified frequency.

You usually only find the slots on the end plates and, as you can see in the video, not all capacitors have the slots. Of course, bending the plates with or without slots will make things change. Just don’t bend enough to short to an adjacent plate or the fixed plates when the capacitor meshes.

Of course, not all variable capacitors have this same design. We’ve seen a lot of strange set ups.

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Old FM Radio Upcycled Into Classy Bluetooth Speaker

December 23, 2025 by 28 Comments

[Distracted by Design] loves gear from the 1980s, though some of it isn’t as useful as it used to be. He happened across a cheap old FM radio with a great look, but wanted to repurpose it into something more modern. Thus, he set about turning this cheap piece of old electronics into a stylish Bluetooth speaker.

All of the original electronics were stripped out, while the original speaker was kept since it neatly fit the case. Electronically, the build relies on a Bluetooth module harvested from an existing speaker. 3D-printed bracketry was used to fasten it neatly into place inside the radio housing, with the buttons neatly presented where the original radio had its tone and volume controls. Power is via an internal lithium-ion battery, charged over USB-C thanks to an off-the-shelf charging module.

Where the build really shines, though, is the detailing. The original cheap plastic handle was replaced with a CNC-machined wooden piece, bolted on with machined aluminium side plates. Similarly, the original clear plastic tuning window was replaced with another tasteful piece of wood that dropped perfectly into place. At the back, the charge port is nicely integrated. Where the radio formerly had a removable door for the power cable storage, it now has a machined aluminium plate hosting the USB-C charge port. Little 3D-printed button actuators were also used to integrate the Bluetooth module’s controls into the case.

It’s a very stylish build, overall. Perhaps the one area it’s a let down is in the sound quality. The ancient speaker simply doesn’t sound great compared to modern Bluetooth speakers and their finely-tuned, bassy audio. However, this isn’t necessarily a bad thing—sometimes it’s nice to have an audio source with a limited frequency response. It can be nice for use in an area where you may want to be able to easily speak over the music.

If you want to build a Bluetooth speaker of your own, you might like to whip up an open-source design from scratch. Video after the break.

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Lessons Learned After Trying MeshCore For Off-grid Text Messaging

December 6, 2025 by 78 Comments

[Michael Lynch] recently decided to delve into the world of off-grid, decentralized communications with MeshCore, because being able to communicate wirelessly with others in a way that does not depend on traditional communication infrastructure is pretty compelling. After getting his hands on a variety of hardware and trying things out, he wrote up his thoughts from the perspective of a hardware-curious software developer.

He ends up testing a variety of things: MeshCore firmware installed on a Heltec V3 board (used via an app over Bluetooth), a similar standalone device with antenna and battery built in (SenseCAP T-1000e, left in the header image), and a Lilygo T-Deck+ (right in the header image above). These all use MeshCore, which is built on and reportedly compatible with Meshtastic, a framework we have featured in the past.

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