When I was a kid, I'd go to the TV repair shops and take old "unrepairable" vacuum tube TVs (no transistors!) off their hands. At home I tried to fix them. I had no idea how to fix them. But I had a lot of fun trying.
One of the fun things was to randomly swap around the vacuum tubes and see what would happen. Very entertaining! I used to have a box full of scavenged tubes. Sadly, I eventually tossed them out, never realizing how valuable they'd be in a few years.
My mom was convinced I was going to electrocute myself, and finally made me get rid of the sets.