Quotebut you'd have to make sure the BJT is biased so it is controlled by its base-emitter voltage, and not the base-emitter currentSo do we ensure this by rewriting physics?
but you'd have to make sure the BJT is biased so it is controlled by its base-emitter voltage, and not the base-emitter current
However, it is entirely possible to use a BJT so that one voltage controls another without violating the known laws of physics!
the current on the base is less then 1mA
The whole point of a BJT is that it is driven by current, not voltage. That current might be small but it is current never the less because it is current that makes the transistor work. FETs on the other hand are voltage devices and draw negligible current apart from the initial charging of the gate source capacitance.
Lets look at each in turn:-1) Common emitter - the normal way I would recommend, base current determines collector current2) Common base - note the page says this is not suitable for a TTL voltage buffer, it has a low gain and typically I use this for video coupling.3) Common collector better known as an emitter follower. - This has no voltage gain but a current gain, you do not need a base resistor because of the feedback on the emitter keeping the emitter / base voltage stable. However this is 0.7V so this means when you use it as a voltage buffer you loose 0.7V. Used with the Due that will reduce the voltage output from 3V3 to 2.6V. When lighting an LED this will not be high enough for blue and white LEDs although it is enough for red and green. Again I would not recommend this due to the voltage drop that it produces.