Vbe in the active region of a 2N3904

R

rameshrai

Member

• Jul 13, 2014

• #1

Hi,

How can I calculate Vbe voltage in the active region of 2N3904 transistor?

thanks

 

alec_t

Well-Known Member

Most Helpful Member

• Jul 13, 2014

• #2

Why not let Spice calculate it for you? Run a sim and plot the base voltage.

 

crutschow

Well-Known Member

Most Helpful Member

• Jul 13, 2014

• #3

Either extrapolate it from the data sheet information or do a Spice simulation as Alec said.

 

ronsimpson

Well-Known Member

Most Helpful Member

• Jul 13, 2014

• #4

crutschow said:

Either extrapolate it from the data sheet information.

Click to expand...

The data sheet should have a graph of Vbe verses Ib at some temperature.

 

audioguru

Well-Known Member

Most Helpful Member

• Jul 13, 2014

• #5

The graphs in a datasheet are for a "typical" transistor that you cannot buy. You might get a transistor with a minimum or maximum Vbe.
Vbe changes with temperature and current.
Usually a transistor has a series emitter resistor and emitter current produces a voltage across it then the base can be fed a voltage then small changes in Vbe do not affect the operation of the transistor.

 

alec_t

Well-Known Member

Most Helpful Member

• Jul 14, 2014

• #6

We seem to have lost the OP

 

atferrari

Well-Known Member

Most Helpful Member

• Jul 14, 2014

• #7

He's busy extrapolating data.

 

Willen

Well-Known Member

• Jul 14, 2014

• #8

He is from Nepal. Nepal is the 2nd richest (after Brazil) country in Water Resources but we (Nepalese) are facing sometime more than 24 hours power failure in a day and more than 18 hours loadscheding in a day. So probably he is getting 0.0Vbe.

 

Last edited: Jul 15, 2014