In late 1945, after the end of World War II, Masaru Ibuka started a radio repair shop in a bomb-damaged department store building in Nihonbashi of Tokyo. The next year, he was joined by his colleague, Akio Morita, and they founded a company called Tokyo Tsushin Kogyo K.K.,[8] (Tokyo Telecommunications Engineering Corporation). The company built Japan's first tape recorder called the Type-G.[8]

In the early 1950s, Ibuka traveled in the United States and heard about Bell Labs' invention of the transistor.[8] He convinced Bell to license the transistor technology to his Japanese company. While most American companies were researching the transistor for its military applications, Ibuka and Morita looked to apply it to communications. Although the American companies Regency[disambiguation needed] and Texas Instruments built the first transistor radios, it was Ibuka's company that made them commercially successful for the first time.

In August 1955, Tokyo Tsushin Kogyo released the Sony TR-55, Japan's first commercially produced transistor radio.[9] They followed up in December of the same year by releasing th


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Cuz back then, they were AM radios. Going near a [power line would make them squeal.
& now, those single transistors, 3 legs poking out of a tiny tin can, are found in the integrated circuits, holding millions ( I guess,, millions, or just hundreds, theyre TINY now). They replaced the tubes. Back in the day, some tubes were called Valves. In a simple tube, with a high Voltage on the plate & the emitter all heated & ready, current flow will be at max, but, put a signal on the grid, a skinny wire, wound around a frame between the plate & emitter, then you can control the current flow thru that tube, by putting a negative charge on the grid,( which is close to the emitter) you cancel out the effect of the + charge on the plate. The emitter cant feel it, so, current flow stops.
Same idea for transistors.Just harder to picture mentally, whats going on in there, with transistors.
Short answer is, a small Voltage on the grid ( tube) or base( transistor) controls the flow thru the part.

I was lucky enough to get the last class they taught in Biloxi Miss on tube theory when I went thru tech school in 73.