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  #1  
Old 05-21-2010, 10:23 AM
Mangrio Mangrio is offline
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Default Instrumentation Amplifier with LM324

Will anyone help me about the Instrumentation Amplifier with LM324 IC.... I have made a circuit with this IC but it is not resulting as it to be

also needed help in resistor combination in above circuit.

I have made this design


Last edited by Mangrio; 05-21-2010 at 10:44 AM. Reason: added image
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Old 05-21-2010, 10:49 AM
t_n_k t_n_k is offline
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The LM324 probably isn't that fantastic a choice to serve as an instrumentation amplifier. It's not surprising the circuit doesn't perform as you hoped.

Posting your circuit schematic would enable a better understanding of your setup & thereby assist forum members in making suggestions for improving your circuit.

OK - see the circuit now!

Last edited by t_n_k; 05-21-2010 at 10:50 AM. Reason: didn't see the schematic at first
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Old 05-21-2010, 10:51 AM
Mangrio Mangrio is offline
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i have posted the diagram, please consider it.
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Old 05-21-2010, 11:44 AM
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t06afre t06afre is offline
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Have you tried www.wikipedia.org they have some usefull info on this topic. Could tell us why it is not working and post the exact schematic for your application. Also what is the range of your input voltage
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Old 05-21-2010, 11:52 AM
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bertus bertus is offline
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Hello,

Here is a page with the circuit you use with some explanation:
http://www.ecircuitcenter.com/Circui...1/instamp1.htm

This is a page from this linkpage on instrumentaion amplifiers from the EDUCYPEDIA:
http://www.educypedia.be/electronics...umentation.htm

Bertus
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Old 05-21-2010, 01:54 PM
Audioguru Audioguru is offline
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Maybe your circuit doesn't work because it has no power supply.
Please show if its power supply has dual polarity and the voltage.

The LM324 works poorly above only 2kHz. It is very noisy. It has crossover distortion.
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Old 05-22-2010, 11:08 AM
Mangrio Mangrio is offline
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Quote:
Originally Posted by Audioguru View Post
Maybe your circuit doesn't work because it has no power supply.
Please show if its power supply has dual polarity and the voltage.

The LM324 works poorly above only 2kHz. It is very noisy. It has crossover distortion.
I have applied power in orignal circuit...
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Old 05-22-2010, 11:12 AM
Mangrio Mangrio is offline
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Quote:
Originally Posted by t_n_k View Post
The LM324 probably isn't that fantastic a choice to serve as an instrumentation amplifier. It's not surprising the circuit doesn't perform as you hoped.

Posting your circuit schematic would enable a better understanding of your setup & thereby assist forum members in making suggestions for improving your circuit.

OK - see the circuit now!
then will you please tell me that what IC i use for IA,

I have to just design a simple instrumentation amplifier (IA) for class work with any range. it just only give right the output.

will you suggest me something else plz.
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Old 05-22-2010, 11:33 AM
t_n_k t_n_k is offline
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Try searching for "AN31 op amp collection".

Section 3 has some examples of 'practical' differential input instrumentation amp circuits. You'll note for instance that 0.1% tolerance resistors are routinely used for the critical components.
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Old 05-22-2010, 01:21 PM
Audioguru Audioguru is offline
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Datasheets for instrumentation amplifier ICs explain why their excellent matching of opamps and resistors produces results that are much better than you can make with separate parts.

There are many high gain intstumentation amplifiers on the web made by students that are made with separate parts and they do not work!.
Maybe if yours has a low gain then it will work about as well as a piece of wire.

You still do not show a power supply for your opamps and whether it has a single polarity or a dual polarity.
You also do not show the input AC and DC voltages.
You also do not explain what is wrong with the output of your circuit.
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