yes you should start a log book
date, purpose of experiment, method, circuit diagram, results, notes, observations, comments, questions, you can take pictures, and do audio/video too if you want
same thing you do in chemistry or physics labs in school, and you learn about the original science experiments, faraday and newton and all them used log books, it is pretty much a necessary fact of the process
the idea is to figure it out and develop the tech, so this is a record and proof of your work. the data you release is of course different, stan never released his experimental notes, only his successes and products, but all engineers and scientists... and doctors.... and lawyers, have logs