This is a practice problem for a test. The objective is to find Vo of the following circuit. All op amps are ideal. I have attempted to start by separating the op amps and calculating Vo accordingly. Starting with the top right op amp as 1. Vo1 = V1(1+R5/R4) and Vo2 = V1( 1 + [(R2+R3)/R1) so Vo would be Vo1+ Vo2
this doesnt seem right. I am more interested in the process to get the answer than the answer.

 

Well see this method

Va = Vin

So

IR1 = Vin /R1

then

Vb = (IR1 * R2 ) + Vin = (Vin /R1 * R2) + Vin = Vin*( R2/R1 +1 )

And

Vo = Vc

IR3 + IR4 = IR1

(Vo - Vb)/R3 + (Vc - Vb)/R4 = Vin/R1

From this we solve for Vo

Vo = Vb + ( Vin * (R3||R4)/R1) ) = Vin*( (R2/R1 +1) + (R3||R4)/R1)

 

I believe you can "weld" R3 and R4 at the right ends (in parallel) since the voltages at the inputs of the second opamp are identical. Nodes which are the same voltage can always be shorted together.

 

so maybe you can help me with this one as well. I tried to create a new thread for this but keep getting server errors. anyways...

All components are Ideal for the following circuit. Calculate a value for R so that R dissipates maximum power. My first thought is to convert R2, R3, and R from Delta to Y, which gets very messy or is there a better way?

 

Remove R and calculate the thevenin equivalent resistance as seen by the open circuit.For maximum power transfer the value of R should be equal to the equivalent resistance calculated

 

Remove R and calculate the thevenin equivalent resistance as seen by the open circuit.For maximum power transfer the value of R should be equal to the equivalent resistance calculated

Sounds right. I don't think R1 even enters the equation. Does it?

 

If R2, R3, R4 and R5 are the same ohmic value, "R" will dissipate ZERO power because there will be no current through it.

 

let me know if this looks correct.

 

let me know if this looks correct.

Looks right to me. Delta-wye conversion. Obviously R1 is in the equation. And yes, bountyhunter has a good point.