Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Summing amplifier help

Status
Not open for further replies.

bungouk

Newbie level 3
Joined
Jan 10, 2012
Messages
4
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,314
Could somebody help me with this one, i don't understand it. I have tried to build the circuit in multisim 11 but i'm not getting anywhere.
so if someone could take a look at the attached zip file and perhaps adjust it so at least the first part of the question works and explain what needed to be done.
I have built well i think most of the circuit but not finished as i got stuck

a – Build and test a summing amplifier with four input voltages V1, V2 , V3 & V4 using multisim . The amplifier should have a voltage gain of 1 , 2, 3 & 0.5 for V1, V2,V3 & V4 inputs


1. Set V1, V2, V3 & V4 to the following voltage levels 1, 2, 0.5 & 3. Monitor Vout with the Multimeter and verify that the voltage gain levels are set correctly.
2. Set V1 to 1KHZ at 10mVPP, V2 to 2KHZ at 20mVPP , V3 to 15 mVPP and V4 to 2V D.C. Monitor Vout with the scope and verify that the gain levels are set correctly. Explain your findings.
3. Modify your summing amplifier to convert the binary number 1101 to an equivalent analogue voltage.
 

Attachments

  • summing amp 4-input.zip
    58.2 KB · Views: 8
  • suming amp.jpg
    suming amp.jpg
    89.2 KB · Views: 40
Last edited:

BradtheRad

Super Moderator
Staff member
Joined
Apr 1, 2011
Messages
14,304
Helped
2,823
Reputation
5,654
Reaction score
2,774
Trophy points
1,393
Location
Minneapolis, Minnesota, USA
Activity points
106,693
1.

Your input resistors need to be in the correct ratio to the feedback resistor. In your schematic only #2 is correct.

You need to change the values of #1,3,4 so that they yield the specified gain.

Can't hand you the solution, but below shows a rough idea how you'll test it with the square wave.

2.

Check that your supply polarities are correct for the pins they're hooked up to.

------------

Edited to upload new schematic with the input waveform corrected to 20 mV P-to-P (10mV nominal).

9236793200_1353227559.png
 

bungouk

Newbie level 3
Joined
Jan 10, 2012
Messages
4
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,314
Thanks BradtheRad, the thing im sturggling with now is find the right resistor combination for getting a gain of 0.5 as well as getting it right for the other gains of 1,2 and 3
 

FvM

Super Moderator
Staff member
Joined
Jan 22, 2008
Messages
49,418
Helped
14,441
Reputation
29,146
Reaction score
13,239
Trophy points
1,393
Location
Bochum, Germany
Activity points
284,384
I hope you already found out that your resistor combination gives gain of -2 for all inputs. I'm not sure if the exercise problem intends negative or positive gain. If negative gain (inverting amplifier) is O.K., you only need to adjust the resistor values. If you mislayed your circuit design text book, that surely has a formula for inverting amplifier gain, you can get the right result by applying rule of three.
 

LvW

Advanced Member level 5
Joined
May 7, 2008
Messages
5,858
Helped
1,746
Reputation
3,496
Reaction score
1,346
Trophy points
1,393
Location
Germany
Activity points
39,555
Could somebody help me with this one,
a – Build and test a summing amplifier with four input voltages V1, V2 , V3 & V4 using multisim . The amplifier should have a voltage gain of 1 , 2, 3 & 0.5 for V1, V2,V3 & V4 inputs
As said by FvM already (implicitely), you only have to apply the classic inverter formulas - for each voltage source separately. However, this leads to NEGATIVE gain values (opposite to your task description).
This can be done as long as the opamp can be considered as ideal (virtual ground principle). In this case, the interaction of the input resistors can be neglected - however, the loop gain is decreased considerably.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top