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TSR
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Join Date: May 2011
Posts: 7

Linear Voltage Amplification

06/08/2011 7:16 AM

Dear All,

we are using a 10k, 10 turn linear pot, the output is given to a IC TL084.Two amplifiers in the IC are used to amplify the signal. one volt dc is given to the pot.+12 & -12 vdc are used to the IC. The output is not linear, for one turn itself it reaching around 50 mv & then raising slowly.

Please guide me how to get the linear output.

sorry if my question looks odd.

Thanks.
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user-deleted-1105
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#1

Re: linear voltage amplification

06/08/2011 7:30 AM

What is the gain of the circuit? What is the circuit configuration?
You need to add resitors to form a circuit with known gain, else the output will just go up and down to rail.
We need a circuit diagram to provide constructive help.
Probably best to build a circuit with a gain of 1 or 2 first to prove it works and then increase it to what you want.
Del

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cuba_pete
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#2
In reply to #1

Re: linear voltage amplification

06/08/2011 10:34 AM

Of course, we will want this to go to 11.
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dcpppf
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#3

Re: Linear Voltage Amplification

06/08/2011 11:41 AM

Yes, a schematic would be very helpful.

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rakesh_semwal
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#4

Re: Linear Voltage Amplification

06/08/2011 12:25 PM
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TSR
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#5

Re: Linear Voltage Amplification

06/09/2011 2:26 AM

Thanks for the replay.

The circuit is enclosed, please give your valuable suggestion.
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user-deleted-1105
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#6
In reply to #5

Re: Linear Voltage Amplification

06/09/2011 3:02 AM

Can't read circuit, too much white space and irrelevant stuff.
crop it and resize before posting. or draw it by hand and scan it.
Del

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Randall
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#7
In reply to #5

Re: Linear Voltage Amplification

06/09/2011 5:29 AM

Use this

free screen capture print tool from: http://www.infonautics.ch/screencaptureprint/

to give us a better view of the schematic.

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Electroman
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#9
In reply to #5

Re: Linear Voltage Amplification

06/09/2011 8:59 PM

From what I can see.... you have a unity gain buffer after a pot which isn't being used!!!! the input is connected to +5 volts (or something)

You won't get far with this circuit mate..... ask an engineer to design one for you....

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Rixter
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#8

Re: Linear Voltage Amplification

06/09/2011 5:57 AM

Here is a paper on Op Amp circuits that might help.

http://users.ece.gatech.edu/mleach/ece3050/sp04/OpAmps01.pdf

Use your 10 turn pot as the feedback resistor (Rf). The gain is the ratio of the feedback resistor divided by the resistor on the inverting input.
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Elroy
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#10

Re: Linear Voltage Amplification

06/10/2011 8:12 AM

As well as circuit design you may want to make sure the potentiometer you are using does not have a taper built into it. It must be a linear potentiometer.

Elroy

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Previous in Forum: want to know about sensor output   Next in Forum: RFID ANTENNA DESIGN , is it complicated?

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