I just read some first pages of "The art of electronics - Paul Horowitz". In chapter 2 transistor it says there are four properties of an NPN transistor (for PNP, it is reversed).
The 2nd property say:
The base-emitter and base-collector circuits behave like diodes. Normally the base-emitter diode is conducting and the base-collector diode is reverse-biased.
Then it says:
Note particularly the effect of property 2. This means you can't go sticking a voltage across the base-emitter terminals, because an enormous current will flow if the base is more positive than the emitter by more than about 0.6 to 0.8 volt.
I don't understand why? Current flow from base to emitter because the base-emitter is conducting-diode so why can't I stick a voltage on those two terminals. If I don't apply a voltage, how can there be a current flowing?
because an enormous current will flow if the base is more positive than the emitter by more than about 0.6 to 0.8 volt
What does this explanation mean? Why is the explanation that a voltage can't be applied to the base-emitter terminal?