I've had a pair of Superex 916 headphones for as long as I can remember. I'm not even sure where they came from, but for at least 25 years they've been kicking around providing me what I consider to be good sound. They're old school, with individual volume controls for each ear, have a stereo/mono switch on the side and are even marked "Property of the Library of Congress." They look about like this:
I say "about" like this, because I had begun this project before I started taking photos. That photo is of a pair of Telex 815 headphones, but as far as I can tell they are identical other than the brand. I don't know if Superex bought or was bought by Telex or if it's a government contract thing.
At any rate, I've found myself using them less and less in recent years, and hadn't touched them at all since my latest phone doesn't even have a headphone jack. Using them with my iPod was ungainly given the massive 1/4" connector compared to the tiny iPod nano that I have. I decided to see what I could do about making them more usable with modern equipment. Enter the coolest little module I've seen in a while:
This little thing is less than 2" x 1". It's actually 40mm x 20mm. It takes in 5v power and has a bluetooth stack and outputs speaker level audio. It costs a whopping $11 or so. I remembered that I had an extra little Lithium Polymer battery pack from a dashcam repair I did previously. It's very compact and 400mah so would be perfect for this project. What the bluetooth module doesn't do, though, is charge or manage batteries in any way. To tend the battery you need a battery charger board. Enter this little wonder:
This is a lithium battery charger/protect circuit, and is even smaller than the bluetooth module, at 25mmx19mm according to the product page. They cost a whopping $1/ea or so and are sold in 5- or 10- packs. I really started to feel like this could work once I found those pieces, so I placed an order and they came in the other day. Here's the collection sitting on my bench with a utility knife for scale.
SO COOL. I had to test the bluetooth module out just to make sure I was happy with it prior to getting down to it. It has both a wire connection for 5V in and a micro USB connection, so I went ahead and hooked up USB and then put the speaker outs into some old bookshelf speakers I had lying around. I turned it on, paired it with my phone, and BAM it was playing music. Completely painlessly and so amazingly compact it makes my Minimus speakers look like giants:
It sounded good, and after letting it run for the better part of an hour the electronics were still completely room temperature to the touch. Amazing. I think this might work!