Help in BJT circuit - How to find Ic - Vce Curve of NPN

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
Post Reply
User avatar
Zedone
Posts: 2
Joined: Tue Apr 11, 2006 2:44 pm
Contact:

Help in BJT circuit - How to find Ic - Vce Curve of NPN

Post by Zedone » Tue Apr 11, 2006 2:47 pm

Image

How can we find Ic (collector current) - Vce (collector emitter voltage) curve (the collector characteristics of an npn transistor) on the oscilloscope?

How can I connect the ch1 and ch2 probes for Ic (Y coordinate) and for Vce (X coordinate)?

We will be changing the potentiometer and adjust Ib (base current) from 0 to 400uA with 100uA steps.
printf("Zedone");

russlk
Posts: 563
Joined: Thu Dec 06, 2001 1:01 am
Location: New Hampshire
Contact:

Post by russlk » Tue Apr 11, 2006 6:05 pm

A resistor in the emitter will measure IC+IB. You can subtract IB with an op amp. Putting a resistor in the collector circuit would be difficult, you would need a common mode canceling circuit.

User avatar
haklesup
Posts: 3056
Joined: Thu Aug 01, 2002 1:01 am
Location: San Jose CA
Contact:

Post by haklesup » Tue Apr 11, 2006 6:07 pm

Normally I would use a curve tracer (but then again, I make curve tracers)


Yahoogle on "Curve Tracer Oscilloscope" and you will find several similar circuits for making one. Basically you are close but you need a series resistor to sense the collector current coming out of the collector source. Stepping the base current to get a full family of curves will be more difficult with an O-scope but getting one Vce vs Ic characteristic should be within reach.

User avatar
Zedone
Posts: 2
Joined: Tue Apr 11, 2006 2:44 pm
Contact:

Post by Zedone » Wed Apr 12, 2006 5:30 am

Image

I tried in Proteus. And I found this graph from o.scope. I really want to learn how to find Ic-Vce curve.

Image

Image

The original circuit is this. Does it effect the results when we connect another component or source? What the fact can I follow here according to the graphs above?
printf("Zedone");

Post Reply

Who is online

Users browsing this forum: No registered users and 57 guests