The discussion revolves around the charging behavior of capacitors, specifically whether they always charge exponentially. Participants explore different charging methods, including constant voltage and constant current sources, and consider the implications of these methods on the charging curve of capacitors.
Participants do not reach a consensus on whether capacitors always charge exponentially, as multiple competing views remain regarding the effects of different charging methods and circuit configurations.
There are limitations in the discussion regarding assumptions about circuit components, the influence of resistance, and the specific configurations of transistors that may affect charging behavior. Participants also note the need for careful analysis to determine the nature of the current source in various scenarios.
It depends on how the capacitor is charged.
If the capacitor is charged from a constant voltage source, it will be charged exponentially as you say.
If the capacitor is charged from a constant current source, it will be charged linearly (as in your recent thread).
The current source will have to work harder and harder to keep its current constant though. ;)
If the capacitor is charged in another way, it will yet be different.
If you have a symbol in your circuit with the text "current source" next to it, it is also a current source. ;)
Note that your mediating transistor also needs constant voltage between the base and the emitter, before it will behave like a current source.
In your previous threads you have seen a couple of examples of that (for instance a zener diode).
What you need is that the current is the same whether the capacitor is full or empty.
If you can calculate the current in both those cases and it is the same, you have a current source.