Last week I found some WiFi Detecting Keychains on sale for $5 and decided they would make a fun weekend hack. I personally don’t like keychain gadgets, but they are great for incorporating into wearable projects because of how small and compact the circuit boards are. Here is a short video of it in action before I took it apart:
The LED at the bottom is red and only lights up when there is no signal. The row of LEDs above indicates signal strength. If you hold the button down an LED at the top acts as a flashlight.
After opening up the casing, I found that the board was nice and compact. At first I thought I would be able to desolder the LEDs and arrange them in a new configuration on a bracelet, but they ended up being too small for my current soldering set up and skill set. For now, I am just focusing incorporating the board and it’s current function into a wearable bracelet.
I soldered some wires to the battery terminals and switch so that I can create soft battery holders and a soft switch. Then I cut out a piece of neoprene with holes to embed the board and batteries in. This gives the bracelet a bit of cushion for the components and keeps everything at a consistent thickness. I placed some conductive fabric and thread to act as battery terminals, and sewed a simple pouch to hold them in place. Finally, some metal snaps connected to the batteries will act as a power switch so that it is only on when the bracelet is being worn.
Unfortunately, during my prototyping/experimenting process, I left the batteries in and one of the loose wires shorted out the board. However, I ordered a second keychain just in case I had any accidents, so I will be trying again soon. The dead board gives me an opportunity to try and get those tiny LEDs off and brainstorm a better design for the final version.