A Homebrew Radio, As All The Best Homebrew Radios Should Be

It started with an old TV sound chip, and some curiosity. The TDA1701 that [Philip Bragg] found in a box of junk is a complete FM IF strip and audio power amplifier from the golden age of analogue PAL televisions, and while it was designed for the 5.5 MHz or 6 MHz FM subcarrier of European broadcast TV, he found it worked rather well at the more usual 10.7 MHz of a radio receiver. There followed a long thread detailing the genesis bit-by-bit of a decent quality VHF radio receiver, built dead-bug-style on a piece of PCB material.

The TDA1701 was soon joined by a couple of stages of IF amplification with a ceramic filter, and then by several iterations of a JFET mixer. A varicap tuned MOSFET RF amplifier followed, and then a local oscillator. Finally it became a fully-functional FM radio, with probably far better performance than most commercial radios. He admits tuning is a little impractical though, with what appears to be a cermet preset potentiometer covering the entire band.

We suspect this project isn’t finished, and we hope he posts the schematic. But it doesn’t really matter if he doesn’t, because the value here isn’t in the design. Instead it lies in the joy of creating an ad-hoc radio just for the fun of it, and that’s something we completely understand.

We’ve covered a lot of radios in our time, and while it might be the first to feature a TV sound chip, it’s not the first built on bare PCB.

You’ve Got Rat!

If you home has never been subject to a rodent invasion then you are fortunate. Our world is full of rats and mice, and despite the best efforts of humanity to keep them at bay it is inevitable that a few will find their way through. For [Marius Taciuc] this became a problem, as his traps needed constant checking to avoid the prospect of a festering rat carcass. His solution? A humane trap equipped with an ESP8266, that notifies him when the rodent is incarcerated.

The tech behind it is about as simple as it’s possible to get, the trap’s door activates a switch, that powers on an ESP8266 module. The ESP’s code simply wakes it up, connects to a wireless network, and sends a query to IFTTT with a call to a service that sends him an email alert. There’s no need to monitor any GPIO lines or have any code running to keep an eye on the trap, it’s all purely a function of the power switch.

The trap itself is interesting, in that it’s a home-made one constructed from soldered copper wire. Sadly there are few details of its construction, but you can see more of it including a live rat inside it, in the video below the break. And if making a trap catches your interest, we can help you there.

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This Mini Soviet Micro Will Have Astounding Attention To Detail

As the retro craze has gone mainstream, we’ve grown used to seeing “mini” versions of classic hardware, preloaded with a selection of games and ready for a wallow in nostalgia. Unfortunately for fans of the less well known platforms, the only devices to get the mini treatment so far are popular ones such as the Nintendo consoles, or the Commodore 64. This is something [Svofski] is aiming to change for one classic micro, by producing a mini version of the Soviet Vector-06c. And unlike the Commodore with its fake keyboard, this one will work in its entirety and have a fully-functional keyboard.

It’s a build that’s not finished yet. But in this case that’s no bad thing, because such is the extreme attention to detail that you’ll want to stick around and watch it unfold. The electronics will come courtesy of an FPGA recreation of the hardware, while the Vector’s unique keyboard is being recreated in miniature, with keycaps designed to fit a particular Alps switch. These are 3D-printed, painted, and then marked with their decals using stencils carefully etched from copper sheet. Even if you have no interest in the Vector-06c, these techniques could find a place in so many other projects.

The wonderfully ingenious and diverse world of Soviet technology has found its way onto these pages many times over the years, including at least one other microcomputer, and even a supercomputer. If your interests extend behind the Iron Curtain though, you might wish to read our colleague [Voja Antonic]’s account of hacking in Communist Yugoslavia.

CampZone 2020 Badge Literally Speaks To Us

The pandemic has left my usual calendar of events in shambles this year. Where I’d have expected to have spent a significant portion of my summer mingling with our wonderful and diverse community worldwide, instead I’m sitting at home cracking open a solitary Club-Mate and listening to muffled techno music while trying to imagine myself in a field somewhere alongside several thousand hackers.

As a knock-on effect of the event cancellations there’s another thing missing this summer, the explosion of creativity in the world of electronic conference badges has faltered. Badges are thin on the ground this year, so the few that have made it to production are to be treasured as reminders that life goes on and there will be another golden summer of hacker camps in the future. This year, the CampZone 2020 badge was given its own voice and perform neat tricks like presenting a programming interface via WebUSB!

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Join Your Own Private LoRa Mesh Network

We are fortunate to live in an age surrounded by means of easy communication, and like never before we can have friends on the other side of the world as well as just down the road. But as many readers will know, this ease of communication comes at a price of sharing public and commercial infrastructure. To communicate with privacy and entirely off-grid remains an elusive prize, but it’s one pursued by Scott Powell with his LoRa QWERTY Messenger. This is a simple pager device that forms a LoRa mesh network with its peers, and passes encrypted messages to those in the same group.

At its heart is a LoRa ESP32 module with a small OLED display and a Blackberry QWERTY keyboard, and an SD card slot. The device’s identity is contained on an SD card, which gives ease of reconfiguration. It’s doubly useful, because it is also a complement to his already existing Ripple LoRa communication project, that uses a smartphone as the front end for a similar board.

We feel this type of secure distributed communication is an exciting application for LoRa, whether it be for kids playing at being spies or for more serious purposes. It’s certainly not the first such project we’ve featured.

A Mobile Phone For The Pulse Dial Generation

One of the useful side effects of the ubiquitous availability of cellular network data modules is that they can be used to create custom mobile phones. It’s surprising in a way that we don’t see as many of these projects as we’d expect, but by way of redressing that deficiency we’re pleased to see the work of [Proton Gamer], who has taken a vintage rotary dial phone and upgraded it with an Arduino and GSM shield to make a very unexpected mobile phone project.

It’s not entirely certain from the write-up which manufacturer produced the donor phone or for which country’s network it was produced, but it seems typical of the type you might have found the world over in the 1960s. We’re given a breakdown of the various components and how to interface to them, the ringer for example is run using a motor driver board. There are comprehensive instructions for the conversion, though sadly they involve gutting the phone and removing the original hardware. The result can be seen in the video below the break, and the finished project makes a mobile phone call from the unlikeliest of hardware.

This certainly isn’t the first rotary dial mobile phone we’ve featured, including one based on a conference badge.

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What Is The Tianwen-1 Probe Saying?

A few days ago, the Chinese National Space Administration launched their Tianwen-1 mission to Mars from their launch site in the province of Hainan. It should arrive at the Red Planet in April 2021, when it will face the daunting task of launching a surface probe from its orbiting component, which will release a rover once it has reached the surface. Like all such missions it’s in constant contact with its controllers on the ground, and as with any radio transmissions floating through the aether its telemetry has been received by the radio hacker community and analaysed by [r00t].

Straight away there’s something interesting in the modulation scheme, instead of a carrier with modulation applied to it there is a main unmodulated centre carrier, and the data appears instead on a series of subcarriers. Is this a feature of its being a space probe, the unmodulated carrier making it easier to find and track in deep space?

They quickly find the telemetry carrier, and decode its frames. It carries a series of data sets, including positional and instrumentation data. From the positional data they can tell when the craft has made any course changes, and from the sensor data such as the solar sensor its movement can be deduced and graphed. It makes for a fascinating insight into the mission, and we’re grateful for the analysis.

Mars is a notoriously difficult target for space probes, somewhere that multiple missions have for various reasons failed to reach. We hope the Tianwen-1 mission is ultimately successful and that in time the Chinese space people will in due course be showing us some of the fruits of their labours. They’re not alone in launching this month, so we’ve got a plethora of Mars-related stories to look forward to next year.

Header image: Tianwen-1 rover mockup. Pablo de León‎ / CC BY-SA 3.0