neato speaker hack (stereo + bluetooth)

I opened my Neato D85 to repair the side brush after its O ring dried out and failed.

While waiting for the replacement O ring, I noticed that Neato had fitted a real speaker instead of using a much cheaper piezo buzzer. Since the speaker was already there, I thought, why not use it to play music?

I used parts that I already had. The Bluetooth receiver is a VHM 314 module that cost about $1, and the amplifier is a PAM8403 module that cost about $0.25. I also added a second speaker for the other stereo channel.

Both speakers should have the same impedance. The original Neato D85 speaker is approximately 25 mm, 8 ohms and rated at 1.5 W. A matching replacement should cost about $0.40.

The tiny device beside the original speaker appears to be marked AJT 436. The package is only about 1 mm by 1 mm, so I was not certain whether it might be a MAX436 family part.

The Bluetooth and amplifier electronics consumed about 190 mW while idle and around 850 mW while playing at full volume. If the extra load prevented the robot from completing a full cleaning cycle, a small separate battery could be added for the music section.

The added speaker was mounted on the side facing the middle of the room. The opposite side carries the side brush and normally faces walls and corners.

It sounded much better and, most importantly, was louder than the boring vacuuming sound. There was still some annoying distortion at high volume, so stronger neodymium speakers would be the next improvement.

Videos:

https://www.youtube.com/watch?v=b6EKfvYa0yk

https://www.youtube.com/watch?v=T5zsCcu4-6s

More photos and videos below.

Photos and videos