If you work with old radios or electronic equipment you will probably find this site interesting:
https://www.youtube.com/c/mrcarlsonslab/featured
Mr. Carlson is very knowledgeable about the theory and practice of radio repair and is one of the best at explaining the topics that you are likely to find.
This link is an example on the topic of radio repair/restoration:
You might be interested in his discussion on capacitors:
He also presents ham radio repair, how to make circuit boards, and test equipment including the Wobbulator. If you snoop around his list of posted videos you will likely find something of interest.
I mentioned Wobbulator to a friend and he told me I was FOS. 🙂
Mr. Carlson totally knows his business!
His workshop alone is a high-end science movie set wonderfully lit and framed professionally by a good camera.
Of a 90-minute "Repairing a Heathkit Signal Tracer" I was pulled in for 30-minutes before I realized the morning was slipping away, but I want to see the rest of the show later on.
Old radios are one thing, but I also recommend these videos to modern viewers dealing with present day equipment, since Mr. Carlson does plenty of explaining about old and new electronics.
And because Neil's great link is presented out in the open here at part15(dot)us, anyone can access it without needing to polish the webmaster's shoes or pass a membership probation.