BJT switch calculation text

You didn't say if this lack is for high power versus low power or at high speed or static etc. But you might find what you are looking for by browsing archive manufacturers applications handbooks and databook compendiums from the mid 1970s thru early 1980s. This is the period when switch mode power supplies were taking off and before mosfets took over the switch role. Some had innovative ways of dealing with storage time and SOA etc and methods to evaluate and select.

piglet

That was a hot topic when folk were first using transistors; the basics are in chapter six here

The application notes for Ferranti e-line transistors (small signal) is online and quite a nice introduction to BJT design (though dated).

For a more theoretical take, this excerpt adapts the small-signal hybrid-π model to large-signal switching:

Thank you very much for the references. Amazing! These are very useful and hard to find, unless you know exactly what to look for and here. I was actually thinking of a much simpler use, like driving a LED or a solenoid, but I guess I will find what I'm looking for in one of these texts. What a shame these things are not teached at the university. Cheers JM

Picking a base resistor that's guaranteed to force a base current greater than Ic/beta when the transistor is in saturation, at the minimum base current specified for that device at that collector current, tends to be good enough for low-speed low power tasks like switching small solenoids and LEDs, don't need to over-think it too much.

For high-current and/or high-speed switching where stuff like temperature de-rating, SOA, charge storage, etc. would become important for BJTs the power FET is often the more appropriate tool for the job in year of our Lord 2021. De-rating is easier for the FET I think; BJTs in power switching applications tend to end up very de-rated cuz there's a lot to go wrong with power switch BJTs pushed to their limits, insufficient base drive makes them very unhappy for example.

Minimum beta, rather

My excerpt comes from my old University of Colorado textbook. So, the University of Colorado, at least, does indeed teach this theory. Danke,

We did get quite an extensive electronics course in the second year. I was from the FET era, and studying physics. The physics practicals considered their behaviour had far more physics content than bipolars.

They did have an unfortunate tendency to die due to static though.

I have indeed used MOSFET in some hig-current applications (LED driver) with the help of people here, but I thought I'd brush up on my BJT in my current project. I'm aware that MOSFET is the way to go, but nevertheless.... I even intend to use a discreate darlington pair to control a motor, just for the sake it.

I also studied FETs on my electronics classes for physicist, but they were all rather teorectical, even the labs. I'm allways looking for these rules-of-tumb that you get from practitioners of engineering. This is why I value google groups so much! Thanks to you all!

Regards JM