Design and simulate a circuit that takes as input a sinusoidal signal

DickCappels

Joined Aug 21, 2008
10,153
No, it was given earlier. 2.2 volts / 0.2 = 11.
Once you find the values for the resistors of a gain of 11, one of the outputs done.

Then you need to think about the output that has the 50 mv offset removed. I can think of two ways of doing that. Smarter people can probably come up with even more ways. Clue: You want to removed the DC component of the signal.
 

Thread Starter

adi80

Joined Oct 8, 2020
132
No, it was given earlier. 2.2 volts / 0.2 = 11.
Once you find the values for the resistors of a gain of 11, one of the outputs done.

Then you need to think about the output that has the 50 mv offset removed. I can think of two ways of doing that. Smarter people can probably come up with even more ways. Clue: You want to removed the DC component of the signal.
I am lost now again :(. so is it ok if i use 8.2 and 3.3 E12 resistors?
 

ronsimpson

Joined Oct 7, 2019
2,986
Clue: You want to removed the DC component of the signal.
Hi Dick, There are many ways to remove the offset. I agree your way is very simple. I think the text book is teaching gain, summing amps and offset in amplifiers. It would be nice to see what the book teaches so we know which way was shown two pages back. I was thinking of pulling up or is it down on the (-) input to add in -50mV of offset. (summing amp) 50mV-50mV=0mV Or do we move the ground point of the R1,2 by 50mV? Is three methods too much at this point? RonS.
 

DickCappels

Joined Aug 21, 2008
10,153
The way you do it is to calculate the ideal resistor values to achieve the gain you need and then select the nearest standard resistor value and accept the tolerance.
 

Thread Starter

adi80

Joined Oct 8, 2020
132
Hello,

You will find a lot of the opamp theory in the attached book.

Bertus
Thank you very much. At the start i taught it is just one assignment which i might never used in life. But after chatting with guys here make me realised that it's better i understand it rather than just getting the answer. So thanks to all of you guys.
 

Thread Starter

adi80

Joined Oct 8, 2020
132
Hi Dick, There are many ways to remove the offset. I agree your way is very simple. I think the text book is teaching gain, summing amps and offset in amplifiers. It would be nice to see what the book teaches so we know which way was shown two pages back. I was thinking of pulling up or is it down on the (-) input to add in -50mV of offset. (summing amp) 50mV-50mV=0mV Or do we move the ground point of the R1,2 by 50mV? Is three methods too much at this point? RonS.
You guys now start different language :). please see the attached file if i am going right direction. Thanks
 

Attachments

dl324

Joined Mar 30, 2015
16,845
please see the attached file if i am going right direction.
You've shown us several schematics for a non-inverting opamp. What you need to do is determine the ratio of Rf to Rin (it's not really the input) that will give the required gain.

The magnitude of the resistors is left to you - hint, - the resistors won't be the same value. As we've already established, that will give you a gain of 2 and that isn't what you want for either part of the problem.

We usually choose them to minimize power dissipation while following other guidelines that consider the opamp input currents.

Unless color coded schematics mean something to you or your teacher, most of us prefer black and white/monochrome.
 
Last edited:

Thread Starter

adi80

Joined Oct 8, 2020
132
You've shown us several schematics for a non-inverting opamp. What you need to do is determine the ratio of Rf to Rin (it's not really the input) that will give the required gain.

The magnitude of the resistors is left to you - hint, - the resistors won't be the same value. As we've already established, that will give you a gain of 2 and that isn't what you want for either part of the problem.

We usually choose them to minimize power dissipation while following other guidelines that consider the opamp input currents.
Thank you guys for all your help but this is not getting into my brain anymore. I spent a good dane half to work it out but no luck. Cheers
 

dl324

Joined Mar 30, 2015
16,845
E 12 series if i use 1.2ohm resistor will it work?
Not likely. Opamps work better when the output is lightly loaded. The uA741 can only sink/source about 25mA. 2V across 1.2 ohms is
\(I=\frac{V}{R}=\frac{2V}{1.2\Omega}=1.67A\)
 

Thread Starter

adi80

Joined Oct 8, 2020
132
Not likely. Opamps work better when the output is lightly loaded. The uA741 can only sink/source about 25mA. 2V across 1.2 ohms is
\(I=\frac{V}{R}=\frac{2V}{1.2\Omega}=1.67A\)
So i have to increase the resistor value? which resistor will it be Rf or Rin ? If i use 8.6 Ohm resistor?
 
Top