Tile Headphone Modification
Project Background
A few months after I purchased a pair of noise cancelling headphones to help me focus while studying, I made the horrible mistake of setting them on a table next to me in the engineering computer lab while I talked to my senior design group. I didn’t notice as I got up to leave that they weren’t around my neck, and I never saw them again. I was left uncomfortable with the extreme loss and angry that I hadn’t paid attention, but I also really missed the comfort that they provided, so I gave in after a week and shelled out the money to buy a replacement pair. This time, though, I had a plan to prevent them from being stolen.
I had tried to find any Bluetooth identification tethered to my old pair of headphones within my phone’s Bluetooth settings in case the pair was ever nearby, so I could try and get them back, but I had no such luck. Public Bluetooth identities seem to change quite often, and I hadn’t saved any identifying tags except for the service tag, which was useless to me at that point unless somebody handed me the headphones.
So, along with my new pair of headphones, I purchased a Tile. It only cost me about 10 dollars on eBay which would easily be worth the money if my headphones were ever stolen again. I didn’t plan on hanging the tile on the headphones, though. My goal was to modify the tile and fit it into the ear of the headphones, hopefully without interfering with the strength of its signal and without breaking it. It took a few tries to reshape its main board, removing unnecessary components and grinding down corners, but in the end, I did successfully implant a working Tile into my headphones. I often play the “find my Tile” tone just for fun and to prove that it works and am relieved to not have to worry as much about carrying my headphones around in public.
Detailed Description
My original plan assumed that there would be ample room in one of the headphones’ ears to fit the mainboard and battery of a tile. Sadly, this was not the case, and I had to rethink how I would get the mainboard, battery and the small speaker to fit in a very thin space. Newer models of Bose QuietComfort headphones attempt to isolate the inside of the ear cup as much as possible from outside noise, with its first line of defense being a rigid plastic shell that fills most of the ear cavity on the outside of the cup. Because of this, there is barely any gap between the driver and the outer metal cover in which another board could fit.
The tile board is designed with protruding metal contacts meant to attach to a battery placed adjacent to them which, with the added thickness of the piezo speaker, made for a thick enough structure that it wouldn’t fit in the gap. I opted to remove the metal contacts in exchange for thin wires leading to a coin cell battery placed away from the board in a more fitting location. The circuitry can be seen through the front and back surfaces of the tile, and I found that two corners of the square-shaped board were entirely unnecessary. Grinding them away allowed the board to fit better between the plastic and metal housings.
The delicate ceramic speaker did at some point get bent a bit too much which cracked the ceramic, and a few pieces of it fell off. I found that the speaker still worked perfectly fine though, so I kept it connected. With those modifications, I was able to fit the board into the three-millimeter-thick gap within the housing and replace the aesthetic plate with no visible indication that the headphones had been tampered with. I then tested the Tile to see how far the signal would reach and was somewhat disappointed to find that it only reached 15 to 20 feet in contrast with the originally advertised 100-150 feet. I assumed that with my limited knowledge of Bluetooth antennae, there wasn’t much that I could do to improve that result, so I settled for it.
The coin cell battery has since died multiple times, which is frustrating because it barely lasts for a month when Tiles are expected to last for a year before needing to be replaced, so I’m afraid that there may be some circuit damage that drains the battery faster than normal. My plan is to test a few other new batteries with it and ensure that it is well-insulated from the surrounding metal components, and if necessary, replace the tile. This was a fun modification project to work on, almost like revenge for having lost my first pair of headphones, even though it isn’t currently functioning as intended. I am sure that I can get it to work the way that I desire, even if I have to tap into the lithium ion battery that powers the headphones to do so.