As I mentioned in my previous post, I’ve had an idea in mind to explore archive material related to Manchester by walking through the streets themselves. After deliberating over a few methods of doing this, I’ve decided that the interface of a portable radio is a great way to do this: you walk around the city carrying the radio, pick up static as you approach a noteworthy location, and tune-in to hear an archival broadcast related to that place.

The process for achieving this is theoretically simple: I load a bunch of audio files onto an SD card, each corresponding with some GPS coordinates in Manchester. The GPS receiver in the radio keeps track of the radio’s location in the city, and will trigger a “static” effect when in range, allowing the “tuner” to be adjusted until the broadcast plays clearly.

After researching a handful of parts – and checking my own “organised” set of supplies – I placed an order for the bits I need: a breakout board capable of playing back audio from an SD card, an amplifier for connecting a speaker, a GPS receiver, a lithium polymer battery, and a battery charger/booster (all pictured above).

Right now, I’ve just started prototyping the circuits (as you can see, I’ve got enough breadboards to keep each component separate and modular for now) and writing a bit of code to try and facilitate the process described above. The GPS breakout board seems pretty accurate and the code libraries for both it and the audio breakout board are very straightforward to use. As a quick test, I’ve got it setup to “tune” through some different static sounds using a potentiometer:

Where do I go from here? Working slightly out of order with how I’d usually proceed with these projects, I’ve already decided on dimensions for my actual radio enclosure (200mm×150mm×100mm) to give myself a size to aim for and avoid making anything too big. I’ve got laser cutting plans drawn up (see the front plate below) and will assemble a prototype enclosure next week.

Radio face drawing

I’ve also discovered – as I usually do when I’m using this amount of parts – this is going to require a lot more power. Running off USB power, the whole thing crashes fairly quickly. It works just fine off the battery, but that inevitably means that it’s going to drain pretty quickly. I’m going to need more power! Luckily, Arduino Manchester has an awesome resident engineer to help troubleshoot this!

I’ve also got a growing list of places and names I’d like to find material about that I’m saving for my next blog post. I’ll also be speaking to Manchester Walks about some of their tours, see if they suggest suitable itineraries for the battery life!

Right, I’ve included a dull parts list, a YouTube video, and a 90s TV reference. I think that’s enough for now!