Boxie – an always offline audio player for my 3 year old

This surely could be recreated with off-the-shelf components, no question. It would be a bit of a challenge to stuff another breakout board into the available space, but certainly doable.

But there's a reason for doing the custom board. As my projects get smaller in size, I need to get away from breakout boards. This project was a good fit to come up with sub circuits for different tasks that I can just copy and paste onto a new design, say for a little gaming handheld, or a micro RC car with a much thinner/smaller form factor.

What might be overkill for the current project might be the enabler for the next project. And it let's me iteratively learn new skills.

That said, I might do another version of this with off the shelf parts only for easier reproducibility.

The weirdest decision, for me, was putting the music on the cartridges, so that each cartridge needs an SD card holder and SD card.

I would imagine putting all the music on the device and just giving each cartridge an address would have been considerably cheaper and easier. This could have been electrically, connecting different pins of the existing battery holder solution; mechanically, such that each cartridge has a key shape that depresses different microswitches in the device; magnetically, using magnets on the cartridges; or optically, using different pattern holes on the cartridges and leds with optical sensors on the device.

I think, personally, I would have gone the mechanical route and just have an array of switches in the device. Then the cartridges can be simple plastic keys and the device can draw no power when there's no cartridge.

I think the Fischer Price record player worked this way: https://www.amazon.co.uk/Fisher-Price-Interactive-Packaging-.... The tracks on the record form a binary number and the record player head has mechanical switches.

I suppose this project served as a source of joy not only to the kid, but to the maker, too. It likely was a good excuse to do a lot of stuff that's not strictly necessary but is fun to do, and buy a lot of gear that's not strictly necessary but is a pleasure to use. The result is somehow better and more solid due to that, too.

Regarding the solidness of the mechanical design, I have my doubts. The volume know is too small, and too close to the navigation buttons. The speaker grill is too coarse, allowing small items to easily drop inside. The cartridge attachment is not sturdy, not self-adjusting, and relatively easy to snap off. If anything, I would rework the mechanical part. (Alas, my kids are too old now.)

Agreed, and it seems to stem from the NiMH requirement. Maybe designing a protective shell around a LiPO battery (to avoid puncture damage) would have made more sense?

Pretty impressive work though! I think you must have learned a lot. I've spent quite some time on about 5 different projects that were way less polished, but it seems we have picked up the same level of skills along the way. The post is very recognizable ;) Looking forward to the your project!

> For people who are thinking about getting into electronics: that project is very complex for what it does.

For people who want to get into electronics, I can recommend getting started with an LED strip, an ESP32 and WLED. You can dip your toes into soldiering, and using an ESP32, for very cheap and with a large margin of error.

I wonder if one of the Anberinc (or similar) devices with single-purpose software would be an option for people shy of going into hardware...

I love this idea!

Any tips for setting up a smartphone with a macropad as mentioned? I like this idea but worry it introduces a lot of complexity for the non-smartphone literate population.

Regarding the cassette player, in the US the 'National Library Service for the Blind and Print Disabled' has a player with an excellent simple interface, using cartridges for each book: https://blog.library.in.gov/wp-content/uploads/2020/04/isl-t...

Could something like [1] work? My understanding is it's a "fake tape" that has an SD slot and can be used in any player.

[1] https://www.amazon.com/Funnytoday365-Telecontrol-Cassette-Pl...

A standard cassette has two hours in it. You can always make larger cassette's yourself.

A Yoto player might work. They're designed for children. They have two knobs (with momentary switch) to control everything (and a small on/off button). They're designed to be usable by children who cannot read, primarily through Yoto cards.

These are just NFC type cards with with some kind of DRM. They allow your player to connect to an API, download the audio content (books, music) and store it locally for instant playback whenever the card is inserted.

Normally I hate vendor lock in stuff like this. But surprisingly they also sell "blank" cards. Using the app you can load any audio content "onto" them (same deal - audio is sent to cloud so it can be redownloaded if local storage runs out). These are pretty cheap and can be "wiped" and reused as many times as you want and you can write on them or mark them up. You can even design a specific image to show on screen when your custom card is inserted.

The hardware is good quality too and can survive daily life.

https://yotoplay.com/

If there is enough material on Spotify, you could grab one of those mini-keyboards with 6 or nine buttons and remap them to play/pause, next, previos, and just leave it on shuffle on one playlist?

A cassette player and some tapes?

Simple, tactile, and they already know how to use it (and it's old knowledge, so they won't forget soon)

Hörbert

Actual cartridges makes sense if there are other players, otherwise a PCB and SD card seems like a huge waste over a nfc card that costs a few cents.

Bonus: The yoto a nice 'normal' bluetooth speaker, as well.

We have a Yoto and it's okay, but my complaint is how difficult it is to get custom stuff on there. The "record-your-own" cards are expensive (and often unavailable, like during this past Christmas season), and off-the-shelf NFC cards don't work perfectly (you have to ensure the content is downloaded onto the device before a generic card will work for that title).

My kids love theirs, and we get tons of comments from other parents since they'll happily listen to stories on them instead of begging for a screen.

They swap cards with their friends, and so long as its on a wifi connection the first time the card is inserted, the local storage is plenty enough to keep the cache there for offline use.

With my kids, I just burned them CDs and bought them $15 CD players. They use them a lot. This gives my wife and I ultimate control over what they play—plus we find CDs at estate sales that allow them to build a collection ~$1 at a time.

I used PLA, which is a non toxic bio plastic. ABS is also an option for at-home 3D printing, which is the material used in lego bricks. At his age, he doesn't put anything in his mouth anymore, so swallow hazards were not a concern. That said, the only thing that's small enough for him to swallow are the buttons and the knob, which can not be detached from the device without unscrewing the enclosure. If he is able to do that, nothing is save.

Next to what others have said (pretty sure there are only very few PLAs who are even close to actual non toxic in terms of small traces of helper materials) but there are finishings you can use to make it food save!

I wouldn't eat from it, but it works and would pretty much solve any issues.

Pretty sure those finishing resins are marketing to finish Beton and stuff like that.

You should never put anything 3D printed into your mouth, regardless if you swallow it or not, because 3D prints aren't "food safe" and may release small pieces.

Also, some materials are hazardous to print (ABS or resin for example) but fine when they've cooled down.