Remember when portable radios (A.M. radio) were the size of a large boom box and used half a dozen "D" batteries and or a lantern battery (a large, heavy, rectangular battery)? Okay, that might be a slight exaggeration. Then, one day came the Japanese transistor radio (with almost the same aural quality as the monster described above), which fit into the palm of your hand and ran on a 9 volt battery.
On that note:
Before the advent of transistors, tubes were the discrete diodes, triodes, etc., that did the rectifying, amplifying, etc. Here’s a link to a very cool video about a craftsman making some tubes, Click here to see video. So you’re aware, the video did not work in my Firefox browser, so I had to use Interpig Exploder. If you can read french, here is some documentation, Click here to find documentation.