If I understand this correctly, a base emitter current of a certain level turns on a transistor.
The part I don't understand is the current gain part. In my understanding, when a transistor turns "on", it means that it allows conduction between the collector and emitter, so it would not matter if the current going between the emitter and collector is 50mA or 500mA. Right? So if Current gain hfe=Ic/Ib, how is constant and computable?
There are holes in my understanding which I'm looking to fill.
What is the use of a darlington pair? If a current in the base of the first transistor switches "on" the transistor, then it would simply conduct fully--> right?
Or is it that the base current is only high enough to get the transistor TR1 to the active mode? --> So we get the base current of the transistor TR2 high enough to set it into saturation mode by connecting it to the emitter of TR1?
The part I don't understand is the current gain part. In my understanding, when a transistor turns "on", it means that it allows conduction between the collector and emitter, so it would not matter if the current going between the emitter and collector is 50mA or 500mA. Right? So if Current gain hfe=Ic/Ib, how is constant and computable?
There are holes in my understanding which I'm looking to fill.
What is the use of a darlington pair? If a current in the base of the first transistor switches "on" the transistor, then it would simply conduct fully--> right?
Or is it that the base current is only high enough to get the transistor TR1 to the active mode? --> So we get the base current of the transistor TR2 high enough to set it into saturation mode by connecting it to the emitter of TR1?