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Amplifier problem (low pass signal)

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tushwatts

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I want to amplify a signal which lies in the frequency range between 0 -5 Hz. And I want a non inverting output with a gain of 33. So basically to amplify this signal , I am using a non inverting amplifier as shown in fig below :

View attachment 116933

The opamp I am using is MCP6002.
But using above configuration, I am not getting the desired result (infact i am getting no output)

But if i use a different configuration as shown in fig below :

Untitled.png

I am getting the desired result with the desired gain.
Why is this anomaly ?
Is there any other technique to amplify a signal with variable frequency ?
 

wade_hassler

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Attatchment schematic of problem-circuit is inaccessible
 

tushwatts

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1.png
here is the actual Attachment 116933
 

Vbase

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BTW in the opamp without the caps you are getting gain of 34.
In the opamp with the caps your gain is about 1. The reason is that for 0 Hz the 10uF is an open circuit so the gain is 1, for 5Hz the 10uF is like 3KOhm and the 0.1uF is like 300KOhm so the gain is about 10.

In real world the technic can be different for every frequency band.
 

schmitt trigger

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Vbase:
"Engineers who use simulators only are named Simulated Engineers."

I like your signature. a lot.:thumbsup:

But perhaps the sentence should read: "Engineers who only use simulators are only Simulated Engineers."
 

Vbase

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Vbase:
"Engineers who use simulators only are named Simulated Engineers."

I like your signature. a lot.:thumbsup:

But perhaps the sentence should read: "Engineers who only use simulators are only Simulated Engineers."
Thanks for the correction of my English, I knew that it wasn't correct but I didn't know how to correct it. I put it right.
I'm glad that you and maybe some others can see the funny side of using simulators. I hope not many will get angry.
I guess if you have very low confidence in your circuit or your circuit is very wrong the simulator can save you some embarrassments :)
 
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crutschow

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......................
I guess if you have very low confidence in your circuit or your circuit is very wrong the simulator can save you some embarrassments :)
If you can design perfect circuits that always work when first built then you are an amazing engineer.
Me, not so much. Simulation has caught many problems (some quite subtle) in my circuits before I built them that were not obvious from looking at them (such as an op amp that had diode protection across its inputs which caused a problem when I used them in a window circuit).
So I never build a circuit without simulating it first. I'm not that keen on troubleshooting and modifying circuits after they are built. :wink:
 

Vbase

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If you can design perfect circuits that always work when first built then you are an amazing engineer.
Me, not so much. Simulation has caught many problems (some quite subtle) in my circuits before I built them that were not obvious from looking at them (such as an op amp that had diode protection across its inputs which caused a problem when I used them in a window circuit).
So I never build a circuit without simulating it first. I'm not that keen on troubleshooting and modifying circuits after they are built. :wink:
Hi Zapper.
It you design and build the perfect circuit then Murphy's Law gets you.
I guess the real competition is between a simulator and a vero-board. I prefer vero-board because it is nearer to the truth.
 

schmitt trigger

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Simulators do have its place in the design environment. And used properly, they will uncover many design flaws.

But to Vbase's point, the engineers that rely exclusively on a simulated design and expect that there won't be any issues when employing real world components, are deluding themselves.
 
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    Vbase

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Audioguru

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I do not know if your simulator knows that an opamp does not work when it is not powered.
Also maybe it does not know that the signal source might not be able to supply a DC bias voltage to the (+) input of the opamp.

Will the input of the opamp be destroyed if the input signal goes more negative than the negative power supply voltage?
 

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