saving private AirPod

 

It all started when...

I leaned out the 3rd-story window of my San Francisco apartment. I was prototyping in the wee hours before an early flight back to Memphis, TN. I was sanding down a 3D print, and I decided to blow the dust out the window.

It was around 4:00 AM, so I wasn't thinking too clearly. I had the window open just enough to yoga my upper body outside. I brought my left arm up enough for my shoulder to hit my ear--and BAM!--my AirPod disappeared into the darkness. Once out of sight, I tracked the AirPod like a bat as it bounced around until it hit the bottom.

I looked at the time, and I had 1 hour before I had to leave for the airport. I rushed outside and went down into the open-air basement. The AirPod had fallen down a 10' by 10' chute that was enclosed by my building and the neighboring building. 

At the bottom of the chute, there was an overflowing trashcan that my 2nd-floor neighbors threw their water bottles into. Next to the trashcan, a fence walled off our basement from the neighboring building. The space between the fence and the neighboring building was just big enough for a water bottle to slide down. The small space was littered with missed water bottle shots, and spiders were EVERYWHERE--I saw at least 12 before I lost count. 

I rummaged through the trashcan for awhile until I thought about the "find my iPhone" app. After some googling and a software update, I was pinging my AirPod. Just as I had feared--the AirPod was ringing at the bottom of the spider infested black hole behind the fence. With just minutes left to leave for the airport, I aborted the mission.

I accepted the fact that I needed to pony up the dough for a replacement. After calling around and a couple of Apple Store (Hipster DMV) visits later, I found out that AirPods had a 6 week lead time. I returned 2 weeks later, and I was determined to rescue my lost comrade. 

I had a few constraints for my rescue operation:

  • - NO CONTACT WITH SPIDERS
  • - No damage to the fence
  • - Spend less than Apple's replacement cost ~$69

A friend jokingly suggested using a magnet tied to a broom--challenge accepted...

As an engineer and avid hackaday.com reader, I decided "I'm gonna have to science the shit out of this" (The Martian 2015). I ran a few errands to collect supplies:

  • Ace Hardware - Zinc Plated Steel Bolt ~$1
  • Fry's Electronics - 24AWG Magnetic Wire ~$3.79 
  • Laying Around - Old 100' Ethernet Cord - FREE
  • DC Bench Power Supply - On-hand - FREE

The video illustrates the build, during which I completely disregarded all safety precautions: no Flyback Diode and an ungrounded wall outlet for the DC power supply. 

During operation, the Power Supply read 3.14 Amps at 11.1 Volts. I roughly estimated the number of turns of the coil to be somewhere between 800 and 950 with some crude back-of-the-envelope calculations. The electromagnet was quite strong--I picked up quite a few metal brackets, nails, and even a child's bicycle.   

The biggest surprise was AirPods charge level. The recovered AirPod had a 64% charge while the other AirPod, which had been sitting in the charger pack for 2 weeks, was at 54%. I must have inductively charged the AirPod during rescue. I was lucky to have created an electromagnet strong enough to pick up the AirPod without damaging the circuit components. I have been using the AirPods for 2 months now, and I have not noticed any issues. 

Thanks for reading. More to come.