Understanding Source Transformations in Operational Amplifier Circuits

[dwn]

Homework Statement

See Image

Homework Equations

Source Transformations

The Attempt at a Solution

The answer is given, but I do not understand how they got it. When I multiply 9mA and 947.308Ω resistor, I get 8.526...what am I doing wrong? Also, could someone explain how they went on to get the final voltage in the simplified circuit. Don't you just add voltages when they are in series like this...?

 

[gneill]

8.526 V + 5.4 V = 13.926 V. So what's the problem?

 

[dwn]

According to their calculation they got .947 V

 

[dwn]

What does the Rf represent as well?

 

[AlephZero]

9 x 0.947 = 0.947 is obviously wrong, and looks like a typo.
It should be 9 x 0.947 = 8.523.

 

[dwn]

I haven't built up a lot of confidence with circuit analysis, so I wanted to make sure that it was in fact an error on there part. Thanks guys.

 

[gneill]

According to their calculation they got .947 V

For what? We need some context here.

What does the Rf represent as well?

Rf is the resistance in the op-amp feedback path.

 

[AlephZero]

What does the Rf represent as well?

The feedback resistor. 150k + 0.740k in series.

 

[dwn]

For what? We need some context here.

This is an online homework site and the guided solution provided a step-by-step solution, which is pictured in the first image I attached. AlphaZero already answered my question.

Thank you for the help.