60 years of popular transistors

In the ever-dynamic and fast-moving world of semiconductors, why do some old transistors like 2N3904 and BC547 keep on going for decades?

The 2N3904 and BC 547 transistor is still available as a newly manufactured device after 60 years of their introduction.

The construction of the 2N3904 and 2N3906 in the mid.1960s represented a significant performance and cost improvement, with the plastic TO-92 case replacing metal cans. 2N3904 has been very popular in USA for general-purpose NPN low-power amplifying or switching applications. 2N3904 is a 200 mA, 40 V, 625 mW transistor with a transition frequency of 300 MHz, with a minimum beta, or current gain, of 100 at a collector current of 10 mA.

The BC548 is a general-purpose NPN bipolar junction transistor commonly used in European and American electronic equipment. It is notably often the first type of bipolar transistor hobbyists encounter and is often featured in designs in hobby electronics magazines where a general-purpose transistor is required. BC548 perfromance characteristics are VCEO = 30 V, IC = 100 mA, Ptotal = 500 mW and (gain-bandwidth product) ft = 150 MHz minimum (300 MHz typical).

The BC548 was released with, and often is found together in datasheets with, the BC547 (higher voltage) and BC549 (lower noise) devices, that correspond to the original BC107 and BC109 variants of the BC108. This group of NPN transistors share many specifications and characteristic curves, but differ in voltage ratings. BC547 transistor is a bipolar junction transistor that was originally developed by Philips and Mullard between 1963 and 1966.

2N3904: Why use a 60-year-old transistor?
https://www.planetanalog.com/2n3904-why-use-a-60-year-old-transistor/

“Note that the 2N3904 is not the only survivor of those early days. Others include its PNP complement, the 2N3906 and the 2N2222, to cite just a few of these dinosaurs that are still listed as active and available.”

“The reality is these classic devices are good but not great in any given parameters by modern standards.”

“When you need a basic transistor to drive a load such as an LED or small motor, these ancient devices do the job and do it cheaply.
They’re around 10 cents each”

“A similar scenario exists for op amps, those basic analog-circuit building blocks. While there are thousands of distinct op amps on the market, some of today’s top sellers are 10, 15, even 20 years old.”

“Have you ever deliberately selected a much-older device for a circuit function in order to reduce various aspects of uncertainty and risk? ”

Why is the 2N3904 transistor still up after 60 years
https://www.edn.com/why-is-the-2n3904-transistor-still-up-after-60-years/

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