# Bipolar Transistor (laboratory exercise)-PSPICE

Discussion in 'Homework Help' started by EleniStefanidou, Mar 27, 2016.

1. ### EleniStefanidou Thread Starter New Member

Jan 14, 2016
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Hi everyone!

My name is Eleni and I am a freshman in the department of automation engineering at TEI of Thessaloniki,Greece.This semester we have in our programm analog electronics which I love but I can't quite understant sometimes.
I have a specific circuit we have to solve and I am not sure how to continue...
These are all the specifications given:

VBB=VCC=5V
R1=4.7k ohm
RC=220 ohm

I found that R2 should be 0.7873k ohm so that the voltage at the base of the transistor is 0.7 V.
1st)Using that I found the current (-11.31 mA) and the voltage (-2.513 V) at the collector.
2nd)After that at a IC-VCE I have to put the Q and design the load line.

Can someone tell me if what I did is wrong and explain to me how to do the second part of my "homework"?
I know almost nothing about transistors and our professor nver explains to us what to do,so I would appreciate any help given.

Thank you so much!!!

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2. ### Jony130 AAC Fanatic!

Feb 17, 2009
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But can post or quote the full question ? And your simulation circuit is wrong the battery are connected backwards.
Rebuild the circuit and repeat the simulation.

3. ### EleniStefanidou Thread Starter New Member

Jan 14, 2016
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Well the post is in greek so I don't know if it will help...So what I had to change was the VBB and VCC?
Thank you!

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4. ### EleniStefanidou Thread Starter New Member

Jan 14, 2016
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What made me post here was the fact the I couldn't find a way to "measure" the VCE requested (2.2).I was requested to put in a Ic-Vce chart the benchmark(?),Q,that I noted.After that I have to design the load line...

Thank you!

Apr 26, 2005
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6. ### EleniStefanidou Thread Starter New Member

Jan 14, 2016
9
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Oh,thank you so much!!!
It's my first time seeing something like this...During the lectures of Electronics our professors haven't yet said to us things like this...

7. ### EleniStefanidou Thread Starter New Member

Jan 14, 2016
9
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I have to find the voltage between the collector and the emitter...but the fact that I put a GND_POWER makes the voltage 0...What does this mean?

8. ### crutschow Expert

Mar 14, 2008
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What does "I put a GND_POWER" mean?

9. ### EleniStefanidou Thread Starter New Member

Jan 14, 2016
9
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In pspice the "common ground" is called like this.

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10. ### EleniStefanidou Thread Starter New Member

Jan 14, 2016
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Maybe I am confused over simple things but today was my first time seeing these.

Also,I am Greek so I am trying really hard to express myself as correctly as I can but ,oh lord is difficult.I'm really sorry for making it difficult for you to help me due to the way I express myself.No matter what I thank all of you for helping.

From the start of this project I couldn't understand how to make the chart when I couldn't even put a voltage marker to measure the VCE...

11. ### crutschow Expert

Mar 14, 2008
13,473
3,361
Okay, but that doesn't fully answer my question.
Where did you put the GND_POWER and where is the voltage 0?

12. ### EleniStefanidou Thread Starter New Member

Jan 14, 2016
9
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Well...this is my circuit all over the right side of the circuit the voltage is 0.I want to find the voltage between the collector and the emitter and I don't know exactly how I will do it.

13. ### crutschow Expert

Mar 14, 2008
13,473
3,361
As you vary the value of R2 from zero to it's maximum (at least 1kΩ), the transistor collector voltage should go from 5V to near zero volts.

An easier way is to use a current source directly into the base, instead of a voltage source with resistors, and vary the current source (pulse mode with slow rise time) from 0 up to say 1 ma and observe the collector voltage.

14. ### EleniStefanidou Thread Starter New Member

Jan 14, 2016
9
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I see ...(but the project was given with resistors and it should be made this way.)
Thank you, I will do this!