AirTag Expansion Card

[ari]

I made an AirTag expansion card! This is my first hardware project, and I did it the jankiest way possible.

I wanted the speaker intact and didn’t want to mess with the battery at all, so I just ground down the plastic casing around the AirTag until it fit inside this old expansion card I had lying around:

Yes, they are ugly. I also have to use electrical tape to keep the battery in. The good news is it doesn’t look too bad when in the Framework:

Everything is functional, including the AirTag’s speaker and ultra-wideband. This is a bit shocking given the tag is enclosed in metal. The distance you can use it from is definitely less than a normal AirTag, but it’s still usable. I can find my laptop from 25ft away.

Now, is this a useful project? Sort of, it would help a lot in case of theft. I also don’t need to deal with third-party software for tracking. Also, if my laptop dies, the tag will remain on. Although, the tag can also die.

Is it kind of wasteful? I’m going to use it, but yeah, it does feel kind of wasteful in hindsight. I don’t really know what I’m going to do with the expansion card internals. I really wish I had a 3D printer for making these cards, that would have come in handy.

Now I have three questions:

1. Given that the tag is enclosed in a metal body (both the expansion card and laptop), could it affect signal strength for Wi-Fi/Bluetooth?
2. The card goes in with some resistance. Is it okay to have a mild amount of pressure in the expansion slot? Is this okay for the AirTag’s button battery?
3. Am I going to get flagged by the TSA for having this in my laptop. It looks so janky, omg.

Thank you for witnessing my janky project. If you have any recommendations for how to make it less janky, I will appreciate them very much!

[amoun]

Q1 Sure can
Q2 Pressure isn’t the way to go but may survive
Q3 You may get on the news as causing a scare at an airport, just don’t go to China, Qatar or any other authoritarian country unless you are language fluent.

[Kris_Keillor]

Nice project!

For the internals: Keep them. You’ve got a male and female USB port there. Since you’re into hardware hacking, I’m sure they’ll come in handy. If they’re still gathering dust after a year, recycle it.

For your questions:

1. Yes it could affect signal strength. Airtags operate over UWB which overlaps both WiFi and BlueTooth. That said, wireless communications is used to mitigating noisy channels. I doubt you will notice too much.
2. How much is “some resistance”? Expansion card bays are fully closed off, so I don’t think a little springiness will bend anything out of shape. But if you’re really forcing it in there, something will probably give eventually.
3. No, you’re not going to get flagged for having electronics in your laptop. Just don’t pull it out and start reassuring them your hacky, taped up, homemade device is perfectly safe, Officer, I swear.

Circling back to the question of the case - yes, it is a shame to have to cannibalize an expansion card. Especially 3D printing it would probably be <$1. You could have that done from an online fab using their provided files, or at a local MakerSpace. I am talking with some folks from Precious Plastic about making a mold to injection-mold EC cases from recycled plastics. If it does happen, I will sell them by the batch (10? 20? not sure) to other Expansion Card makers.

[ari]

Thank you all for the likes and the answers to my questions!

From testing for a few days, it doesn’t seem that signal strength is too affected. I haven’t noticed any changes, although I spend a lot of time near the router, so who knows.

@Kris_Keillor

How much is “some resistance”?

It was enough that I got a little worried and decided to shelve the project for now, sadly.

@Kris_Keillor

No, you’re not going to get flagged for having electronics in your laptop. Just don’t pull it out and start reassuring them your hacky, taped up, homemade device is perfectly safe, Officer, I swear.

Lmao, this would be me. But that is reassuring, thank you!

@Kris_Keillor

You could have that done from an online fab using their provided files , or at a local MakerSpace.

This is a great point! I had no idea it would be so cheap. I’m going to look into if there are any Maker Spaces near me, but do you recommend any online fabs?

@Kris_Keillor

I am talking with some folks from Precious Plastic about making a mold to injection-mold EC cases from recycled plastics. If it does happen, I will sell them by the batch (10? 20? not sure) to other Expansion Card makers.

That’d be fantastic, you can count me as a customer!

[Thomaatje]

This is a very nice little project. Shame though it doesn’t fit as a drop-into-expansion-card (in my mind the tag was a lot smaller, don’t have a tag nearby though). an expansion card as dedicated tracker is great idea. Keeping an eye on this one. The models mentioned by @Kris_Keillor are great as a starting point for the expansion card development.

[dac]

Some public libraries offer 3D printing services if you want to try something local.

[Ranko_Kohime]

The depth of an AirTag is listed at 8mm, while a quick Googling says the expansion cards are 6.8mm.

For a less janky look, perhaps a 3D printed expansion blank could be printed that exposed the rounded face to the bottom of the laptop? (Similar to the way this Yubikey button was exposed here)