Hackaday Podcast Episode 391: Tuned In To ESP32 SDR, New Old Pagers, And Bugs On Mars

October 16, 2026 by Tom Nardi 3 Comments

Hackaday Editors Elliot Williams and Tom Nardi start this episode off with a discussion about Philadelphia’s budding hacker conference and the imminent retirement of the EZ80. After considering the parallels between the wide world of aviation headsets and our personal projects, talk moves on to the exciting developments in the world of software-defined radio on the ESP32, a Meshtastic pager from a bygone era, and how all the wild flying machines entered into DARPA’s Lift Challenge ended up losing to a simple helicopter.

You’ll also hear about turning plastic bottles into printer filament, pushing e-ink screens to their limits, and browsing the web on the PSP in 2026. To wrap things up they’ll marvel at all the modern abstraction sitting between software and the memory it’s running on, and revisit some RF concepts that might be particularly useful now that everyone is playing with a new SDR device.

Check out the links if you want to follow along, and as always, tell us what you think about this episode in the comments!

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The Casio F-91W As A Contactless Payment Device.

August 24, 2026 by Jenny List 9 Comments

The Casio F-91W digital watch is perhaps one of the most successful pieces of consumer electronics ever made, having quietly supplied the essential function of an inexpensive and accurate LCD digital timepiece for many decades. As a result it has a huge following, and we’ve seen plenty of projects based upon it. [Matteo P] has one that we think you’ll like, he’s turned his Casio into a contactless payment device. We missed it when it came out, but sometimes a good project needs sharing.

If you’re a long-time Hackaday reader you may remember our investigation of 13.56 MHz NFC cards in which we showed you a disassembled card in which he antenna was a tuned circuit covering most of the card, with a small coupling coil for the chip. It’s this kind of card he uses, and ends up with an SLA printed front face for the watch that places the chip above the display and puts a pick-up coil around the outside. The most interesting part of the write-up though isn’t in the build, instead it’s the deep-dive into designing the RF parts and ensuring a good coupling at something close to resonance. Read it, if you fancy trying NFC-enabling any other random items.

Meanwhile, if this NFC bug has caught you, don’t forget our rather silly one transistor 125kHz NFC reader challenge.

Thanks to Hackaday alum [John Elliot V] for the tip!

Bringing A Yagi Antenna To 915MHz LoRa

December 31, 2025 by Tyler August 36 Comments

If you’re a regular reader of Hackaday, you may have noticed a certain fondness for Meshtastic devices, and the LoRa protocol more generally. LoRa is a great, low-power radio communications standards, but sometimes the antennas you get with the modules can leave you wanting more. That’s why [Chris Prioli] at the Gloucester County Amateur Radio Club in the great state of New Jersey have got a Yagi antenna for North America’s 915 MHz LoRa band.

Right out the gate, their article links to one of ours, where [tastes_the_code] builds a Yagi antenna for the European 868 MHz LoRa. Like [tastes_the_code], the radio club found [Chris]’s antenna gives much better reception than what came with the LoRa module. Looking out their window, instead of two Metastatic nodes with a stock antenna, one club member is now connecting to two hundred.

A simulation of the radiation pattern. Looks like a Yagi, alright.

Now, the Yagi is directional, so you only get that boost pointed down the axis of the antenna, but at least in simulation they estimate a 7.7 dB front-to-back gain vs under 3 dB for an omnidirectional antenna. Not bad, for a simple 3D print and some stiff wire!

If you don’t want to re-invent the wheel again, check out the GCARC’s GitHub for files if you’re in North America. If you’re in Europe, check out [taste_the_code]’s build from last year. Of course whatever band you’re operating in, Yagi isn’t your only roll-your-own option for a LoRa antenna.

Thanks to [Jon Pearce WB2MNF] for the tip!

915 MHz Forecast: Rolling Your Own Offline Weather Station

December 19, 2025 by Matt Varian 12 Comments

There are a lot of options for local weather stations; most of them, however, are sensors tied to a base station, often requiring an internet connection to access all features. [Vinnie] over at vinthewrench has published his exploration into an off-grid weather station revolving around a Raspberry Pi and an RTL-SDR for communications.

The weather station has several aspects to it. The main sensor package [Vinnie] settled on was the Ecowitt WS90, capable of measuring wind speed, wind direction, temperature, humidity, light, UVI, and rain amount. The WS90 communicates at 915 MHz, which can be read using the rtl_433 project. The WS90 is also available for purchase as a standalone sensor, allowing [Vinnie] to implement his own base station.

For the base station, [Vinnie] uses a weatherproof enclosure that houses a 12V battery with charger to act as a local UPS. This powers the brains of the operation: a Raspberry Pi. Hooked to the Pi is an RTL-SDR with a 915 MHz antenna. The Pi receives an update from the WS90 roughly every 5 seconds, which it can decode using the rtl_433 library. The Pi then turns that packet into structured JSON.

The JSON is fed into a weather model backend that handles keeping track of trends in the sensor data, as well as the health of the sensor station. The backend has an API that allows for a dashboard weather site for [Vinnie], no internet required.

Thanks, [Vinnie], for sending in your off-grid weather station project. Check out his site to read more about his process, and head over to the GitHub page to check out the technical details of his implementation. This is a great addition to some of the other DIY weather stations we’ve featured here.

Revision D PCB of Mockingboard with GI AY-3-8913 PSGs.

Something Is Very Wrong With The AY-3-8913 Sound Generator

April 15, 2025 by Maya Posch 14 Comments

The General Instruments AY-3-8910 was a quite popular Programmable Sound Generator (PSG) that saw itself used in a wide variety of systems, including Apple II soundcards such as the Mockingboard and various arcade systems. In addition to the Yamaha variants (e.g. YM2149), two cut-down were created by GI: these being the AY-3-8912 and the AY-3-8913, which should have been differentiated only by the number of GPIO banks broken out in the IC package (one or zero, respectively). However, research by [fenarinarsa] and others have shown that the AY-3-8913 variant has some actual hardware issues as a PSG.

With only 24 pins, the AY-3-8913 is significantly easier to integrate than the 40-pin AY-3-8910, at the cost of the (rarely used) GPIO functionality, but as it turns out with a few gotchas in terms of timing and register access. Although the Mockingboard originally used the AY-3-8910, latter revisions would use two AY-3-8913 instead, including the MS revision that was the Mac version of the Mindscape Music Board for IBM PCs.

The first hint that something was off with the AY-3-8913 came when [fenarinarsa] was experimenting with effect composition on an Apple II and noticed very poor sound quality, as demonstrated in an example comparison video (also embedded below). The issue was very pronounced in bass envelopes, with an oscilloscope capture showing a very distorted output compared to a YM2149. As for why this was not noticed decades ago can likely be explained by that the current chiptune scene is pushing the hardware in very different ways than back then.

As for potential solutions, the [French Touch] project has created an adapter to allow an AY-3-8910 (or YM2149) to be used in place of an AY-3-8913.

Top image: Revision D PCB of Mockingboard with GI AY-3-8913 PSGs.

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Taking A $15 Casio F91W 5,000 Meters Underwater

February 1, 2025 by Maya Posch 42 Comments

When considering our favorite spy movies and kin that involve deep-sea diving, we’d generally expect to see some high-end watch that costs thousands of dollars and is specially engineered to withstand the immense pressures kilometers below the ocean’s surface. Yet what about a humble Casio F91W that can be bought for about $15 if it’s the genuine article and not one of the millions of fakes? Over at the Watches of Espionage site they figured that they’d dress up one of these famous watches to give it the best possible shot at surviving the crushing pressures at a depth of 5 km.

The actual modification to the F91W was pretty mild, involving nothing but a ‘hydro-mod’ whereby oil is used to replace the air inside the watch case. Since oil is incompressible, nothing bad should happen to the watch. Theoretically at least. The Watch-Under-Test (WUT) was strapped to a US Navy’s CURV 21 remotely operated vehicle and dunked into the ocean before starting its descend into the inky darkness of the deep sea.

Although only hitting a measly 4,950 m, the watch survived just fine, showing that even if you’re a secret US operative on a deep-dive espionage mission, all you really need is one of these Casio watches.

Hackaday Podcast Episode 291: Walking In Space, Lead In The Earth, And Atoms Under The DIY Microscope

October 4, 2024 by Al Williams 2 Comments

What have you missed on Hackaday this week? Elliot Williams and Al Williams compare notes on their favorites from the week, and you are invited. The guys may have said too much about the Supercon badge this year — listen in for a few hints about what it will be about.

For hacks, you’ll hear about scanning tunneling microscopes, power management for small Linux systems, and lots of inertial measurement units. The guys talked about a few impossible hacks for consumer electronics, from hacking a laptop, to custom cell phones.

Of course, there are plenty more long-form articles of the week, including a brief history of what can go wrong on a spacewalk and how to get the lead out (of the ground). Don’t forget to take a stab at the What’s That Sound competition and maybe score a sweet Hackaday Podcast T-shirt.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

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