Regarding Transistor in saturation and cut off mode

[ajsivsan]

Dear guys,

When the collector of a NPN is connected to 5V and the emitter is grounded via 1K, What will be collector voltage when the base is given 5V???
Will that be same that appear at the emitter, since theoritically a transistor acts as a closed switch or the voltage will be different??

 

[bananasiong]

Hi,

I say the collector have 5 V regardless what stage since it is constantly connected to 5V.
As for the emitter, it is 0 V when 0 V to the base, while 4.3 V when 5 V to the base.
You don't use a NPN in this way, do you? The load should be at the collector.

Thanks

 

[ericgibbs]

Hi,

I say the collector have 5 V regardless what stage since it is constantly connected to 5V.
As for the emitter, it is 0 V when 0 V to the base, while 4.3 V when 5 V to the base.
You don't use a NPN in this way, do you? The load should be at the collector.

Thanks

hi bananasiong,
When the resistor is in the emitter lead the configuration is called an emitter follower.
It has a high input impedance and low output impedance and is in common use.

 

[crutschow]

Will that be same that appear at the emitter, since theoritically a transistor acts as a closed switch or the voltage will be different??

The transistor acts as a switch only when configured that way, which is typically with the emitter grounded and the load in the collector.

When configured as an emitter-follower, (common collector), it acts as a linear amplifier with a voltage gain of approximately +1.