Say you have a simple NPN BJT switching circuit to control a light bulb (attached image) and say you rotate the potentiometer so that the BASE of the transistor moves towards +Vcc.
Now this may be a silly question, but why does the voltage between the BASE and ground not increase past ~+0.7 V even though it is physically connected to a voltage close to +Vcc?
I realize that the voltage between the BASE and EMITTER is ~0.7V due to the junction bias and the EMITTER is grounded but it just seems to me that it is magic that when you apply any voltage greater than 0.7V on the BASE of the grounded common-emitter NPN that the BASE voltage magically moves from whatever large voltage down to ~0.7V.
Maybe I am just not in the right mindset but I can't picture this one.
Thanks,
JP
Now this may be a silly question, but why does the voltage between the BASE and ground not increase past ~+0.7 V even though it is physically connected to a voltage close to +Vcc?
I realize that the voltage between the BASE and EMITTER is ~0.7V due to the junction bias and the EMITTER is grounded but it just seems to me that it is magic that when you apply any voltage greater than 0.7V on the BASE of the grounded common-emitter NPN that the BASE voltage magically moves from whatever large voltage down to ~0.7V.
Maybe I am just not in the right mindset but I can't picture this one.
Thanks,
JP
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