Transistors Lessons
https://www.youtube.com/watch?v=jMXHLJXhsh8&list=PLA8D2D29f-gJJhCFfTec5vhUTq-G8H5Ou&index=20
https://www.youtube.com/watch?v=QvPGMpDM33Q
https://www.youtube.com/watch?v=7ukDKVHnac4