i was doing troubleshooting for circuits and the transistor was bad because Vbe was about 3vd insteade of being .7v my question is why when Vbe is high or very low this mean that the transistor is bad
please can you explain phsically why when vbe is high the transistor is openTransistors start conducting meaningful amounts of current when Vbe reaches around 0.6v, and by the time Vbe is around 1V or so, it's at around 60%-75% of it's maximum rated collector current.
Basically, the base-emitter junction acts like a forward-biased silicon diode. They usually don't start conducting a meaningful amount of current until around 0.55v or so, and they're near or at their maximum current at ~2v.
So, if a silicon transistor that is supposed to read between ~0.6v and ~2v from base to emitter reads outside of that range, it's either turned off deliberately (no current flowing through the base current limiting resistor), shorted if lower than ~0.6v, or open if higher than ~1.5v.