[Michael] likes this old organ of his, but recently he wondered if it would be possible to add MIDI out without altering its original functionality. With a bit of research study as well as a lot more than a bit of difficult work he accomplished his goal.
The great thing about working on a high quality piece of hardware such as this is the resources you can discover relating to exactly how they work (which we bet is tailored for exactly how to repair work them when they break). [Michael] discovered a web site with lots of information on the circuit boards as well as exactly how they work. From this he was able to find a few chips which stream serial data relating to which secrets have been pressed. Bingo!
Once he found the three signals he was after he developed a board to equate them to the MIDI protocol. His circuit is based around an ATtiny2313. It is supported by a liner voltage regulator circuit in addition to a buffer chip which converts the incoming signals to the 5V levels needed. His house etched board is clean as well as well mounted, as well as the success of the job can be heard in the clip after the jump.