I use my phone a lot in the car to listen to music and podcasts. With subsonic I have full access to my entire music catalog which makes it a no brainer to use instead of fooling with CDs. However I found myself really missing having physical buttons to control pause, play, and track skipping. Aside from the convenience, it was also a little dangerous for me to be messing with my phone while driving. Inevitably, I would end up hitting the wrong button, and that would be an even bigger distraction.
I knew headphones were sold that provided some external controls for phones so I did a little digging and came across this post where someone had already solved my problem.
I ordered the parts and when they came in I got my breadboard, alligator cables, etc. and brought it all to McDonald’s and spent a little bit of time mocking up the solution. The old ladies that I hang out with there were impressed by my ingenuity. I told them I was just following someone else’s instructions, but still they persisted :)
I made a couple of variations from Rich’s design. On the skip forward switch I used a 470 ohm resistor — it’s what I had handy and it worked. I couldn’t find a SPDT limit switch that I liked so I just used momentary normally open switches, one for each function (pause/play, skip forward, and skip backwards).
One of the hardest parts of the project was making a case. I had some 1/16″ thick wood left over from making a cajón a couple of months ago. So I used that to make the enclosure. I installed the buttons on the top piece, and the TRRS jack (this goes to the phone) and TRS jack (this goes to the car’s aux port) on the sides and then glued them all together. It was a precarious combination, and I had to take great care not to break it while soldering all the connections. I hot glued two pieces of copper wire to the inside of the top to provide connection points for the switches and resistors. In hindsight, hot glue wasn’t the best choice since things get pretty hot while soldering. Once all the connection were made, I glued the sides and back on.
I tried to find a TRRS cable to go between the phone and the control box, but they are non-existent. So I had to make one of those too. I used 22ga wire and shrink wrap to make it look somewhat like a real cable. The 22ga wire was almost too big, and if I were to do it again I would use 24ga wire.
It’s so nice to have physical controls again, and a lot safer too. I’m no longer swerving all over as I drive down the road. Well that’s not true, I still swerve a good bit, but no longer because I’m trying to replay the last song.