AirTag compatible speaker

Electronics
1

Hello everyone :slightly_smiling_face:

I’m not an expert in electronics, and I have a project to modify an Apple AirTag to make it fit in a credit card format (85mm x 55mm) while remaining as thin as possible (3.5mm) to put it in my wallet.

I already have the PCB with the shell removed, cables soldered on the power contactors to place the battery next to the PCB, and a temporary cardboard case (until I make a 3D-printed one). Everything works fine! :ok_hand:

Now, I need to replace the AirTag speaker. Indeed, I would not like to reuse the integrated coil because:

  • the operation seems very difficult (the wires are very tiny, I already broke them during disassembly :grimacing:).
  • the volume will be lower without the original shell (see the post below), and I find a normal AirTag already too quiet.
  • I don’t need to save space, there is plenty of room in a credit card format to easily fit the PCB, a battery, and a speaker as long as it is thin.

So I looked up the specs of the AirTag’s audio circuit and came across a great doc by Adam Catley (see the post bellow). It mentions that the audio amplifier is a Maxim MAX98357AEWL whose specs are available here.

I then looked for a speaker that both have a good thickness/decibel ratio and that is compatible with the AirTag. I found a lot of models on Alibaba (strangely, I found almost none on Digikey), and this one seems to check all the boxes:

  • 3.3mm thickness (the AirTag PCB is 3.5mm)
  • good decibel level compared to the different models I’ve seen (I hope it’s a lot louder than an original AirTag :crossed_fingers:)
  • specs seem to be compatible with those of the amplifier: Rated / Max. power: 0.7W / 1W ; Impedance: 8Ω

So I would like to get some advice on this choice. Is it really the audio amplifier that determines the choice of the speaker? Do the specs actually match, or am I wrong?

Thanks in advance :slightly_smiling_face:

1 Like
2

I had to delete 4 or 5 links from my post above because being a new user, I am limited to 2 links per post.

Here are the two most important ones:

3

This is a very cool project. I found this post since I also was looking to add in my own speaker. Did you ever get this working? Did your speaker work or did you go with something else?

4

No, I waited for a response for a while, then when I didn’t get one, I ended up moving on.
I think I’ll just order some speakers and give it a try.

5

Sorry, I do not remember seeing this post.
The speaker that you referenced above should work but I would expect it to be lower volume as it is 8 ohms vs the 4 ohms that the specs recommend.
You can determine the specs for the voice coil in your original tag by measuring it with an Ohm meter.

Here is a 4 ohm: For Toy Loud Sound Micro Round 30mm 4 Ohm 2w Mylar Speaker - Buy 30mm Mylar Speaker,4 Ohm 2w Speaker,Mylar Speaker Product on Alibaba.com

Found this reference: AirTag For Your Wallet - YouTube
I am not sure how the speaker is implemented in this one. I guess the voice coil is mechanically connected to the plastic case.

2 Likes
6

Thank you for your answer. :slight_smile:

Unfortunately, following my message yesterday, I ordered two sets of speakers (speaker 1, speaker 2) without having seen your answer. I hope the fact that they are 8 ohms won’t make the sound too weak. I got one in 1W and the other in 0.5W.

Well, since it’s Aliexpress, delivery was announced for mid-February. But I’ll update this thread when I’ve received and tested the speakers. :+1:

2 Likes
7

Heres a pretty good speaker I found on digikey:

One with a little worse low end response: - but the startup sounds from adam catley are around 3kHz

8

This thread is pretty much solved. But here is my update on my iteration of this project:

There’s a video there as well as a brief description of the way I did it.