The Parts Around Us: Part One

It’s 2023. It’s too quiet. You need some background music to accompany what you are working on. You reach into your pocket, the entire history of the worlds combined music library is available to you through a glass obelisk you carefully slide out from your pocket. Spotify, Apple Music, Soundcloud (the best one), the others. You select one of your pre-made radio stations that the algorithm has prepared for you. You listen to your echo-chamber of music that it knows you will enjoy. It’s just nice.

While all this is happening, invisible sounds are riding through your body, emanating from various radio stations in the area. I recently became fascinated with radio, and the electronics behind transmitting and receiving these sneaky lil waves. There’s something about switching on the radio and having no clue what you’re going to get, that makes a listening session much more enjoyable. “Wow, I haven’t heard that song in ages, I completely forgot about this band.”.

Music has the power to thrust you into a memory. The smell of that funny plant floating through the air when The Tragically Hip’s “Ahead by a Century” comes on. Cemented in my brain from so many nights having that song come on during formative moments, good times and bad. That night in Whitby, partying with my parents and friends, in the rental house we were staying in because our house had burnt to the ground and exploded a few months earlier (a story for another time). I find that streaming services can still elicit these feelings and emotions. But for some reason when it’s selected by another person, sent through the air, captured by a little device, and played through horrible speakers, that feeling is amplified.

So, this brings us to our first part. I came across this part while disassembling a portable radio as I was trying to learn about the integrated circuits these little cheap radios were using. It practically screamed out to me: “Hey, look at this! Bet you never thought about this!”

I am talking about this part:

This flexible part is the radio frequency indicator that slides back and fourth behind the transparent window to show the frequency that the radio is tuned to.

I dont really know why such a simple part gave me such a pause. I had always assumed there was some sort of belt or string loop pulling back and fourth a little flag, or something along those lines. This solution just just seems so clean. In an effort to see if this was now standard fare in cheap pocket radios, I did what any normal human would do and ordered 4 more radios to crack them open and take a look for myself.

I love these things.

All four radios had the exact same setup. Some tuning dial through the side of the enclosure. This tuning dial is a stacked with a toothed gear that mates with the teeth on the indicator part. The pitch circle circumference of the gear attached to the tuning dial is the length of the adjustment window. The tuning dial is attached to an adjustable capacitor that tunes the local oscillator frequency of the radio, allowing you to select which frequency to listen to.

Part One is that little white (or sometimes orange/red) flag, that travels back and fourth in the indicator window.

I particularly love this solution, because of its incredibly low cost, and complete reduction of assembly complexity. The housing parts have an alignment window that allows the flag to be inserted into the guiding slot during assembly.

I imagine the assembly process goes something like this:

1. The two enclosure halves are each assembled as a sub assembly with their respective electronics attached.

2. The flag is inserted (as shown above) into the flag slot. This aligns the flag at the minimum tuning frequency.

3. The tuning dial is rotated into its minimum tuning frequency position.

4. The two halves are assembled together. Meshing the teeth of the gear with the teeth of the indicator in the process.

This assembly process varied across the multiple radios, some had the board and dial attached to the same enclosure side as the indicator window. I imagine having them both on the same side of the enclosure makes assembly easier.

What also interesting here, is that across the two cheapest radios, the flag part was exactly the same. Same tooth count, same dimensions, same parting line. These parts likely came from the same mold, or the exact same mold design that has been copied across manufacturers. The design of the enclosures are different, so it’s not just a white label product that is being sold under different names. The PCBs are also similar, but different in their design, routing, and selection of hardware.

Having a look around at who is responsible for this design lead me down a deep rabbit hole of patents for indicating mechanisms for personal radios. My final co-op position during my stint at UWaterloo was at Blakes, right smack dab in the middle of downtown Toronto. Doing these sorts of prior art patent searches was my job. Learning how to dive deep through a technology’s progression via patents was a lot of fun. There is so much work that goes into IP protection and classification; it’s an undulating machine in and of itself that some never get a peek at. Google patents is a great resource for basic search, there are other paid options from Thompsons Reuters that allow for even more advanced searching. I am sure that there are people working hard on tuned LLMs specific for patent search and application automation.

There is indeed a unique classification for just about anything in patent law, including “Pointers, markers, or the like, for tuning dials”.

After some searching, I believe I have come across the first mention of this sort of arrangement in a patent. Of course, I may have missed something. This claim is from patent GB2037516B.

But this patent isn’t exactly the same configuration as what we see before us in the form of Part One. It is a huge simplification of the claims of the above patent. Alas, I cannot find a specific mention of something like this flexible geared indicator. But I will keep searching and come back to update this article if I find anything.

I would love to be able to talk to the person who originally came up with this design. The tool designer who took the part CAD and formed the tool CAD that would make it mass manufacturable. The first machinist to fabricate the tools. I fear that I may never have these conversations, and that’s all right. The manifestation of their efforts will forever live on in these little pieces of plastic that sing memories to you.

For now, let’s place these parts in the archive for safe keeping.

I hope you enjoyed this look into just one of the many Parts Around Us.