Help with Circuit to Invert Graph

  • Thread starter sheheryarnoor
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In summary, the person is asking for a tutorial on how to make a circuit that will invert the frequency response of an amplifier.
  • #1
sheheryarnoor
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Hi everyone i got project from someone

Here is the Project
Code: 
www.stanford.edu/class/ee122/Spice_Decks/pspicedemo.pdf

And i did the same what the pdf file tells

Here yall can see the video which i made

Code: 
[URL]http://rapidshare.com/files/390247187/CaptureWiz005.wmv
[/URL]

Or

Code: 
http://www.youtube.com/watch?v=4G82E2uDP2A

But rapidhsare one's quality is good


Circuit Pic
qnwryx.png



kcb040.png



The graph which i want to invert
1jx734.png


Can someone help me with inverting the graph?
What should i add in the circuit to invert the graph?
 
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  • #2
Welcome to PF.

The circuit you have is called a http://en.wikipedia.org/wiki/Low-pass_filter" .
 
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  • #3
dlgoff said:
Welcome to PF.

The circuit you have is called a Low-pass filter. If you want to invert your frequency response, you'll need a High-pass filter.
I think he's probably referring to inverting the amplitude, since it's an "inverting" amplifier topology.

To sheheryarnoor: Just plot the phase response and you'll find it's already "inverted" (as in 180 degrees phase shift in most of the pass band). What you have plotted there is a frequency response "magnitude". The magnitude will always be positive, you need to plot the phase to confirm whether it's "inverting" or not.
 
  • #4
i made a circuit like this
2lvfnu8.png

But it gives me error.Isn't it same like high pass filter?i think it is but it is still giving me error
Can anyone make a video tutorial for me please
I need it for my friend he is in the hospital:(
 
  • #5
This is an inverting amp with a gain of A=R2/R1. i.e. Vout=AVin
 
  • #6
can anyone of u make a video tutorial of it for me?
or just draw a circuit even in Paint so i can know how the circuit will look like and what components there will be
Please i want to help my friend he is in the hospital
 
  • #7
You need to connect the positive side of Vin to C1 and the negative input to ground -- right now you've got the negative side of Vin connected to C1 and an open circuit on the positive side. And also remove the voltage source on the output, and put your probe here.
 
  • #8
i removed voltage source and connected as u said
n654pg.png


But the graph shows like this then

24c9j0w.png
 
  • #9
When I said "the positive side" I meant the terminal that has a "+" sign next to it. The negative side has a "-" sign next to it. I'm not sure what you're trying to do anymore, but in your last attached picture (which I guess is supposed to be an "integrator"):

1) Connect the positive output of Vin (marked with a + sign) to the 1k resistor and the negative side to ground.

2) Connect the negative input of the opamp to the node where the resistors and capacitor meet, and the positive input of the opamp to ground.If your input signal is a square pulse train, what do you expect to get on the output?
 
  • #10
98yk5z.jpg


30w72hd.png


See the red lines i want graph like those red lines the red lines have been sketched in Paint to give me a clue that what graph will look like
Can u make like these?
Actually i am not a student of Electronics i am doing it for my friend he is in the hospital so i want to help him
Please help me to help him
 
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  • #11
dlgoff said:
This is an inverting amp with a gain of A=R2/R1. i.e. Vout=AVin

Oops. Actually it is a high pass filter. I didn't see the capacitor at first. Sorry. The corner frequency = 1/2πR1C1 with a bandpass gain of R2/R1.
 
  • #12
lol as i told u am not a student of electronics just helping my friend
So i don't know what are u talking abt?:p
Can u make a graph like the red line?
 
  • #13
You can combine low pass and high pass filters to get passbands like that one.

[PLAIN]http://dl.dropbox.com/u/4222062/low%20pass%20high%20pass.PNG

Here R2 and C1 form a low pass filter to produce the slope from 10 KHz upwards and
C2 and R1 form a high pass filter to produce the slope from 1 KHz downwards.
 
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  • #14
what is this triangle thing which u have used?
GND Analog?or what?
 
  • #15
"vk6kro" Can u make a video of it?I tried to make a circuit like u have shown but mine graph was change it wasn't like urs
So i wish u make a video of it
 
  • #16
The triangle is a ground symbol.

Not sure what sort of video you mean. Why would you do that?

Are you plotting with LT Spice 4?
 
  • #17
"My friend's in hospital and the only thing that will cure him is a video of the simulation of a band-pass filter"

Man you've got to give this guy the award for most creative excuse of why someone else should do my homework/assignment for me. :smile:
 
  • #18
Hopefully his friend will have a speedy recovery and be able to do his own homework. :)

I'm sure we all wish him well.
 
  • #19
i mean get a screen recorder and when u make a circuit record it and then upload it to utube so i can see what did u do and what did i do wrong
 
  • #20
i mean make a circuit and graph like u have showed in ur pics
While making them make a video of it
Record ur screen by screen recorder so i can know what did i do wrong?
Upload it to youtube or rapidshare then
Can u do it please
 
  • #21
sheheryarnoor said:
i mean get a screen recorder and when u make a circuit record it and then upload it to utube so i can see what did u do and what did i do wrong

That isn't going to happen.

When your friend gets out of hospital, you can give him that circuit and he can do a simulation of it.

Note that the output should go to a high impedance load such as the input of an opamp connected as a unity gain buffer.
 
  • #22
Why man:-s
Why can't u do that?
 
  • #23
Vk6kro thanks bro i did it
Thank u so much i made a circuit like u have shown in the pic
I tried to make a graph like this but mine don't show like this
Can u make a circuit which can have graph like this on Vout

w70pdf.jpg
 
  • #24
Could you show the circuit you entered into the simulator?
 
  • #25
which one?
The one u made like it?
Or the one which i made wrong?
if u are talking abt the 2nd one then can't lol coz i saved and deleted the files coz it was wrong
 
  • #26
I already have a copy of my circuit. To work out what you are doing, I need a copy of your version of it.

Try entering just the signal source and the first 100 K resistor R2 and C1. Then try entering the rest of the circuit but without the 270 pF capacitor.
You should get results like this:

[PLAIN]http://dl.dropbox.com/u/4222062/low%20pass%20high%20pass%203.PNG

Can you see that the combination of these outputs will give the bandpass shape I got before?
 
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  • #27
Thankss 4 keep helping me but the one u made isn't what i need ur one look diff than the graph which i showed
i have mostly done it
Thanks again
 
  • #28
Anyone know how to make a circuit which can have graph like this on Vout
6i87fb.png
 
  • #29
Yes, have a look at the first circuit in post #26.

That one peaks at 50 volts because the supply is 100 volts. You would need a supply of 4 volts peak.
R2 isn't necessary and you would get the same shaped graph without it, but twice as much output.

Those graphs were drawn to let you find out what you were doing wrong with the simulator.

How is your friend in hospital?
 
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  • #30
He is on medicines thanks for asking
Can u draw a circuit actually i m having exam
i am a student of computer science and i am into 3d designing so i don't know about electronics much
Draw a circuit for me and i will try to make a circuit like and will make a video if i do something wrong u will see it in the video
O.K
SO u can guide me
Can u please?
 
  • #31
sheheryarnoor said:
He is on medicines thanks for asking
Can u draw a circuit actually i m having exam
i am a student of computer science and i am into 3d designing so i don't know about electronics much
Draw a circuit for me and i will try to make a circuit like and will make a video if i do something wrong u will see it in the video
O.K
SO u can guide me
Can u please?

You don't know about Electronics but you are doing an exam in it? That is amazing.

Anyway, here is a high pass filter:
[PLAIN]http://dl.dropbox.com/u/4222062/high-pass.PNG

Can you see how it works?
The capacitor has less and less reactance as the frequency rises, so it drops less of the input voltage and more gets to the output.
 
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  • #32
vk6kro said:
You don't know about Electronics but you are doing an exam in it? That is amazing.

Anyway, here is a high pass filter:
[PLAIN]http://dl.dropbox.com/u/4222062/high-pass.PNG[/QUOTE]
I'm not sure anymore but I think he was wanting a op-amp circuit. Think you'll be able to explain it before the exam? :devil:
 
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  • #33
No problem. :)

I was wondering if some Butterworth filter pole-zero diagrams might cheer his friend up a bit and speed his recovery?
 
  • #34
lol u are funny
So u gona show me a circuit diagram?
 
  • #35
Which circuit are you looking for?
 

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