MIRROR SIGNAL with operational amplifiers

Thread Starter

bisonte

Joined Jul 12, 2021
4
Hi everybody.

I hope you are ok.
I'm going to start...I have a project with operational amplifieres, in this project I need to create a mirror signal(simetrical signal) from this output :
1626141562955.png



Something like this:

1626141653703.png



The two requierement are:

  • Only use operational amplifiers, resistences and capacitors
  • The circuit must have two inputs 1 square signal and a triangule signal
I 've trying with many settings , but I have not succeeded.
.
I have this circuit with the original output :
1626141958997.png



But, that's all.

If someone can help me I will appreciate it.!

Thank you
 

MrAl

Joined Jun 17, 2014
8,547
Hi everybody.

I hope you are ok.
I'm going to start...I have a project with operational amplifieres, in this project I need to create a mirror signal(simetrical signal) from this output :
1626141562955.png



Something like this:

1626141653703.png



The two requierement are:

  • Only use operational amplifiers, resistences and capacitors
  • The circuit must have two inputs 1 square signal and a triangule signal
I 've trying with many settings , but I have not succeeded.
.
I have this circuit with the original output :
1626141958997.png



But, that's all.

If someone can help me I will appreciate it.!

Thank you
Hi,

You need to show the amplitude of your output signal as well as the shape.

Your app requires an inversion and an offset addition and maybe a gain (to be determined after your reply). Do you know how to invert a signal and add an offset and with gain perhaps?
 

BobTPH

Joined Jun 5, 2013
4,030
The two signals you show are not a mirror images. If you really wanted it "mirrored", i.e. reflected around the x axis, a simple inverter would do that.

Bob
 

MrAl

Joined Jun 17, 2014
8,547
The two signals you show are not a mirror images. If you really wanted it "mirrored", i.e. reflected around the x axis, a simple inverter would do that.

Bob
It looks like he wants it 'mirrored' and also level shifted because of the drawing he provided, but also a possible gain adjustment. This is why i asked him about that.
 

Thread Starter

bisonte

Joined Jul 12, 2021
4
Hi,

You need to show the amplitude of your output signal as well as the shape.

Your app requires an inversion and an offset addition and maybe a gain (to be determined after your reply). Do you know how to invert a signal and add an offset and with gain perhaps?
Thanks for answering Mr Al, exactly what you comment is what I require. Regarding inverting the signal, I suppose it is about putting an inverting amplifier at the output of the circuit that I show, but the offset and gain do not know how to do it. This is the image with the amplitude

1626199937980.png
 

MrChips

Joined Oct 2, 2009
24,609
Depends on what you mean by “mirror”. Maybe that is not the correct word to use.

It could mean different things:
1) Symmetrical about the x-axis
2) Invert
3) form the negative
 

Thread Starter

bisonte

Joined Jul 12, 2021
4
Depends on what you mean by “mirror”. Maybe that is not the correct word to use.

It could mean different things:
1) Symmetrical about the x-axis
2) Invert
3) form the negative
yes, I used the incorrect word, I need a Symmetrical about the x-axis

Something like this

Original:

1626201714578.png


desired output
1626201869088.png
 

MrChips

Joined Oct 2, 2009
24,609
The first waveform is not symmetrical about the x-axis, neither is the second waveform.

The second waveform is reversed in time (i.e. about the y-axis). That is not going to be easy to do.
I think that this is not what you want.
 

MrAl

Joined Jun 17, 2014
8,547
yes, I used the incorrect word, I need a Symmetrical about the x-axis

Something like this

Original:

View attachment 243397


desired output
View attachment 243398
Hello again,

Ok just to be clear, pick one of the waveforms from the attached drawing.
Choose either Mod A, Mod B, Mod C, or Mod D.
You can alter the amplitudes if you want instead of +6 and -6 volts make it whatever you need or leave it as is if you want it to be plus and minus 6 volts as shown.
Mod A requires a DC offset addition.
Mod B requires a square wave and DC offset and maybe inversion also.
Mod C requires DC offset and inversion.
Mod D requires DC offset and inversion and square wave.
Either one could also require a gain change but you will have to verify the amplitudes for us first.

To get inversion yes you use an inverting op amp with or without gain.
To get offset you sum a DC voltage along with the original signal.
To get the slope change you have to sum a square wave along with the signal and possibly a gain change and offset.
Once you decide which waveform is best we can talk about this in more detail.

WaveMod-02.png
 
Last edited:

MrAl

Joined Jun 17, 2014
8,547
Thanks for you answering .
I think you have clarified a lot of things for me. The signal I require is MOD B
Thanks @MrAl
Hi,

You're welcome, and since i think you understand how to get an inversion, do you know how to add a DC offset based on the summing properties of op amps? We could look at that first.
What you could start with is a design where you have to add a DC offset first as that would be something good to know even for other designs.
You think you could create a design that gives you Mod A in the drawing by 'subtracting' 2 volts from the input signal you gave as "original" ? That would be a good starting point, then we can look at inversion if you want to and then how to get a reversed slope using a square wave. You first should understand how an op amp can be used as a voltage summing circuit where you have two voltages you want to sum and the output of course becomes the total sum of the two voltages.
If you dont think you can create a subtractor based on these concepts then try designing a simple summer that sums two input voltages like 2 volts and 3 volts and you of course should get 5 volts on the output.

I am suggesting this order of design because each step will take you closer to the final design and then you will understand exactly why we did everything the way we did and that will be applicable to many designs you have to do in the future too.
 
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