OP-AMP question?

Wendy

Joined Mar 24, 2008
23,809
The op amp will likely go to full voltage on either power supply rail, so it depends on the component being used. Very few op amps anywhere near the power supply rails.

You don't have a component for the op amp, you don't have power supply definitions.

In short, as stated the question is unanswerable.
 

mik3

Joined Feb 4, 2008
4,843
Find V- (inverting input voltage with respect to ground) and V+ (non inverting input voltage with respect to ground).

Then equate V- and V+ (ideal op amp) and you should find Vo with respect to Vin.
 

mik3

Joined Feb 4, 2008
4,843
V+=(Vo*12k)/(12k+8k)=0.6*Vo , voltage divider rule

current through 4k and 16k is: assume current flows from Vo to 6V

I=(Vo-6)/(4+16)k=(Vo-6)/20k

thus

V-=6+I*4k=6+4k(Vo-6)/20k=6+(Vo-6)*0.2=6+0.2*Vo-1.2=0.2*Vo+4.8

assuming V-=V+

0.6*Vo=0.2*Vo+4.8

thus

0.4*Vo=4.8

thus

Vo=12V

Io=12V/10k=1.2mA
 

hgmjr

Joined Jan 28, 2005
9,027
Millman's Theorem Solution.......

\(\small V_-=V_+\)

\(\frac{\frac{6}{4K}+{\frac{V_o}{16K}}}{\frac{1}{4K}+{\frac{1}{16K}}}=\frac{\frac{V_o}{8K}}{\frac{1}{8K}+{\frac{1}{12K}}}\)

\(\frac{6(16K)+4K(V_o)}{16K+4K}=\frac{12K(V_o)}{12K+8K}\)

\(\frac{6(16K)+4K(V_o)}{20K}=\frac{12K(V_o)}{20K}\)

\(\normalsize {6(16K)+4K(V_o)}={12K(V_o)}\)

\(\normalsize {8K(V_o)}={6(16K)}\)

\(\large {V_o}={\frac{6(16K)}{8K}}\)

\(\large {V_o}={6(2)}\)

\(\large {V_o}=12V\)

****************************************

\(V_+=\frac{12K(12)}{12K+8K}\)

\(V_+=\frac{12K(12)}{20K}\)

\(V_+=7.2V\)

****************************************

\(I_o=\frac{V_o-V_-}{16K}+\frac{V_o-V_+}{8K}+\frac{V_o}{10K}\)

\(I_o=\frac{12-7.2}{16K}+\frac{12-7.2}{8K}+\frac{12}{10K}\)

\(I_o=\frac{12-7.2}{16K}+\frac{12-7.2}{8K}+\frac{12}{10K}\)

\(I_o=0.0003+0.0006+0.0012=0.0021A\)

hgmjr
 
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