# indicate where should be NPN and PNP transistors?

#### mrTalos

Joined Nov 1, 2016
7
Hi everyone. Please help me to understand this problem. I have attached the problem itself and my version of solution. I think I made some mistakes, maybe not. I could not draw output signals for current. I will be glad and thankful if someone will show me the right way of solving this.

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#### dl324

Joined Mar 30, 2015
15,536
Check your work and you should be able to determine whether you made any mistakes.

Regarding current waveforms. What is the relationship between voltage across a resistor and the current through it?

#### mrTalos

Joined Nov 1, 2016
7
Current will have the less amplitude than voltage, right? I

#### mrTalos

Joined Nov 1, 2016
7
Current will have the less amplitude than voltage, right? I
I think the current will have the same waveform as the voltage? Am I right?

#### dl324

Joined Mar 30, 2015
15,536
Current will have the less amplitude than voltage, right?
Can you calculate current values without a value for the resistor?

#### mrTalos

Joined Nov 1, 2016
7
Can you calculate current values without a value for the resistor?
Of course not

#### dl324

Joined Mar 30, 2015
15,536
I think the current will have the same waveform as the voltage?
What is the relationship between the voltage across a resistor and the current through it?

#### dl324

Joined Mar 30, 2015
15,536
Of course not
Then how can you calculate current amplitude (magnitude)?

#### dl324

Joined Mar 30, 2015
15,536
Let's try a different approach...

For the NPN transistor. What is the current in the resistor when the collector is at 0V? What is it when the collector is at VCC?

#### WBahn

Joined Mar 31, 2012
28,517
Current will have the less amplitude than voltage, right? I
This is like saying that a person's height will be less than their weight or that a car's speed will be less than the gas it consumes. It's nonsensical.

What is the relationship between voltage and current in a resistor?

#### WBahn

Joined Mar 31, 2012
28,517
What are the differences between the two circuits (as given)?

#### LesJones

Joined Jan 8, 2017
4,008
The two drawings are the same but drawn differently. The question is badly written as it does not say if a common emitter configuration or an emitter follower configuration is required. So there can be more than one correct answer.

Les.

#### WBahn

Joined Mar 31, 2012
28,517
That's the point I was hoping the TS would realize by trying to describe the differences - they would discover that there isn't any. So putting an NPN in one and a PNP in the other makes no sense -- unless, of course, there can be more than one reasonable answer.