In my quest to find uses for lesser Raspberry Pi 2s that have been replaced by 3s, I needed some speaker output. Rather than order a perfectly good Adafruit amp module, I decided to see what I could re-purpose from the local discount warehouse.
Portable Bluetooth speakers are everywhere, so older non-Bluetooth ones are sliding down the price scale. These “Splash” speakers, in fuggly green or purple, take audio and deliver surprising output (3W), powered/charged by USB. In ~$6 range depending on the clearance sale.
Naturally I dissected one. Board date stamp is 9/2012. The main board has an op amp, stereo jack (only right channel used), USB mini for power, a blue LED that could be used for emergency lighting, The 3.7V 320mAh battery unit seems to have all the power/charging/volt-shift stuff included. (I haven’t explored with a multi-meter yet to see what’s going on.) There are a couple of diodes on the main board, probably to prevent back-feeding to USB connection.
I tried driving it from a Pi, via a USB sound card, sending the amp output to a Radio Shack Minimus-7 speaker, and it wasn’t bad. Not head-banger, but loud enough for me.
Meanwhile, the grill fits nicely into a sanitary tee of 1.5" PVC tubing. I won’t be mounting them that deep, but exactly how will depend on what I can find. (A 2" brass washer with 1.5" inner hole would be perfect.)
The Pi, screen and power bank will fit into a 3" PVC piece. Still thinking about it, but hopefully the end result will look like Captain Nemo’s Atari.
ETA: The thing about PVC bits is that a piece that accepts 3" inner diameter pipe will have 3.5" inner diameter female hub connectors to fit it. A 1.5" bit will have 2" hubs. Some bits have male (pipe) connectors, but it’s mainly hubs. Go to Home Depot and see what they have. When the guy asks what you’re looking for, tell him it’s for a Victorian retro-science fiction computer project. No problem!