I just looove stuff like that..
I was sort of restraining myself for a long time because, well, sweetie, neighbors, friends, embarrassment at being less than a beginner, etc. but now we both have decided to go for it. so, I suppose, let the embarrassment begin!
If you want to get into building electronic music machines I cannot recommend this book more highly. The second half of it takes you through all of the op-amps and CMOS IC’s that you already know and love and shows you specific electronic music circuits using them. This book is gold for the electronic music hobbyist. So sad that the author Ray Wilson passed away.
https://www.goodreads.com/book/show/16144497-makeAnd, as a recording engineer, touring tech and synth programmer, repairer and restorer I just have to say this, (and I don’t want to insult anyone but I have lived the music industry all my life and have worked on thousands of concerts around the world) the very best thing that anyone into electronic music can invest their first $500.00 into is music lessons and theory study.
Being that this is the golden age of the modular synthesizer (who would have thought!) I see people with massive modular systems that they obsessively build larger and larger and all that they do with them is to make rhythmic bleeps and post them on YouTube. The modular synthesizer has become the train set of the 21st century. They get bigger and bigger for their own sake.
The most fun, satisfying and rewarding way to do electronic music is to get one synth, a basket of guitar pedals and any kind of audio recorder and just start laying up tracks layer by layer and if you have some keyboard skills this is all you need. I might get flamed for this but I know that learning your scales and modes and timing is the best electronic music investment that you will ever make. If you take the time to learn some keyboard skills then you can take a simple mono-synth, borrow a flanger pedal from your guitarist friend and start shredding and you will have a ball.