# Summing Amplifier Question!

#### aly34

Joined Jan 29, 2012
20
1. The problem statement, all variables and given/known data

2. Relevant equations

Absolutely no idea how to start this problem!

3. The attempt at a solution

A) I would think that there are 4 input combinations for this circuit.

B) 0110 = 6v?

C) No clue

D) 1011 = 11v?

E) No clue

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#### BSomer

Joined Dec 28, 2011
434
3. The attempt at a solution

A) I would think that there are 4 input combinations for this circuit.

B) 0110 = 6v?

C) No clue

D) 1011 = 11v?

E) No clue

A) it is a 4 bit combination

E) see (A)

As for B,C & D you will have to do some math to figure out what Vs is. It is not necessarily a binary - decimal conversion. The formula for Vs is pretty much given in the question B.

#### aly34

Joined Jan 29, 2012
20
A) it is a 4 bit combination

E) see (A)

As for B,C & D you will have to do some math to figure out what Vs is. It is not necessarily a binary - decimal conversion. The formula for Vs is pretty much given in the question B.
For E:

would it just be:
0000
0001
0010
...
1111
?

And B: Not sure what formula?

C: Would it just be sin(w*f*t) = sin(4000*f*t)

so, w*f*t = 4000*f*t

and so f = 2000hz?

#### t06afre

Joined May 11, 2009
5,934
This will be a job for the superposition theorem. Just Google superposition theorem. And you will get a lot of hits that will be helpful. Since the network is resistive. The vout will be Vs multiplied with a constant regardless of vs is DC or AC. Assuming ideal components

#### crutschow

Joined Mar 14, 2008
27,728
As the title of your thread states, it is a summing amplifier. So the output is the sum of all the inputs that are energized. And the gain for each input to output is just the feedback resistor divided by the input resistor. For those values of resistors give all the gains are less than one.

#### bountyhunter

Joined Sep 7, 2009
2,512
another simpler way to look at it: whatever input paths are connected to the source signal, puts those source resistors in parallel. Combine them to get an equivalent source resistor value and then the gain equation is simple.

#### bountyhunter

Joined Sep 7, 2009
2,512
A) I would think that there are 4 input combinations for this circuit.
I can tell you that is wrong. It's a lot more, but not so many you couldn't easily go through them one at a time by toggling each bit.