I've been watching a fair few of Moritz Klein videos on YouTube - he goes into detail about how components work, explaining things from the basics and working up to full circuits.
It's biased towards synth stuff, but I think it's still relevant to pedals.
Anyway, here's one I just watched about sample and hold circuits. Hoping someone might find it useful or interesting!
https://m.youtube.com/watch?v=kIJqzkRe4do