You Can Now Use Bluetooth Headphones with Your Sony MiniDisc Player!
If you still own a MiniDisc player and you want to bring it into the modern era, this conversion lets you connect Bluetooth headphones.
MiniDisc was a strange and relatively obscure medium for music storage, which was mildly successful right around the time that MP3 players like the iPod were hitting the market. A MiniDisc is essentially a tiny re-writable CD in a little plastic enclosure. A single MiniDisc could store up to 80 minutes of audio, but was far more compact than a CD. That made it an attractive option at a time when MP3 players still had mere megabytes of storage. If you're lucky enough to still own a MiniDisc player and you want to bring it into the modern era, Daniel Rojas developed a conversion that lets you connect Bluetooth headphones.
Sony developed the MiniDisc format and almost all of the MiniDisc players that were available. The most iconic and popular of those was the Sony Walkman MZ-R5x line, which had a few different variations. Personally, I had (and still own) the MZ-R505. Rojas seems to have built prototypes with a couple of different units and his current prototype (v0.3) is in an MZ-500. This conversion should, however, work on many different models, because it isn't dependent on any specific feature — though you will need to figure out which PCB traces connect to the control buttons.
Performing this conversion requires a handful of components: a Scosche FlyTunes Bluetooth transmitter module, a Pololu U1V11F3 voltage regulator, two ED8 audio transformers, a Microchip ATtiny13A microcontroller, and a handful of miscellaneous components like resistors.
The conversion process requires some hardware hacking skill, but the operating principle is pretty simple. The audio signal pumps out to the Scosche Bluetooth transmitter through the transformers, and then broadcasts to whatever speaker or headphones you want to connect. The ATtiny13A microcontroller activates the Bluetooth transmitter as soon as the MiniDisc player turns on. The original buttons connect to the Bluetooth transmitter, so the user can hold down the Search button to initiate pairing or press the volume buttons to change the output volume on the connected speaker/headphones (as opposed to the internal amplifier).
There aren't many people left on the planet who still use MiniDisc players, much less that want to connect them to Bluetooth devices. But for the six people who fit the bill, Rojas's work is indispensable.