How to amplify the voltage in(milli volts to volts )using opamp 741 with constant gain

Thread Starter

andhavarapu lokesh

Joined Aug 17, 2017
46
hello everyone goodevening


I am trying to use Opamp 741 to amplify the lower voltages in milli(0.003-0.133)volts. but i am not able to get constant gain in non inverting configuration
i am using LM741 IC,Rf=29.8Kohm,Ri=978ohm

Can any body suggest any circuite or opamp
 

jayanthd

Joined Jul 4, 2015
904
hello everyone goodevening


I am trying to use Opamp 741 to amplify the lower voltages in milli(0.003-0.133)volts. but i am not able to get constant gain in non inverting configuration
i am using LM741 IC,Rf=29.8Kohm,Ri=978ohm

Can any body suggest any circuite or opamp

What is the output voltage range you want ? 0-5V ? If yes, then use Rail to Rail OpAmp like MCP6001.

Still better use Instrumentation Amplifier like LTC2053.
 
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Picbuster

Joined Dec 2, 2013
1,022
use microchip mcp6291 and read the AN (application notes).

lm741 is old fashion and uses a lot of energy to operate plus a double supply.
when your output should swing around zero double supply is needed (see AN).

Picbuster
 

Thread Starter

andhavarapu lokesh

Joined Aug 17, 2017
46
i have one more doubt if we give input voltage 0.001 volts to non inverting pin of MCP what will be the output of the amplifier
what is the formula of vout
 

Picbuster

Joined Dec 2, 2013
1,022
yes out put lies within 0-5v but is there any circuite sir
Don't get me wrong but I expect you to consult internet first (eq using Google).
Do not expect us to think for you!
And YES we like to help you wen you get stuck and only after you have done your homework.
What you want is easy to find on the internet.
Picbuster
 

Thread Starter

andhavarapu lokesh

Joined Aug 17, 2017
46
thank you sir but can you tell me what maximum output can it give if i gi
Try this and reply.

What is the application ?

For R26 you can use 35k. Use 1% or 0.1% resistors.

Can you use LTC2051 ? 300 rupees OpAmp ?



Try this and reply.

What is the application ?

For R26 you can use 35k. Use 1% or 0.1% resistors.

Can you use LTC2051 ? 300 rupees OpAmp ?



hi sir is there this IC MCP6291 in LTSPICE tool
 

AnalogKid

Joined Aug 1, 2013
8,676
The circuit in #14 has issues. Any input offset voltage and/or bias current errors will be multiplied by the gain of the circuit.

To the TS:

What power supply voltages are available for the opamp?

What is the frequency range of the input signal?

What do you mean by "not able to get constant gain"? What gain does your circuit produce? In what way is the gain changing?

Please post your original schematic. While the 741 is not very good by today standards, there is no reason why its gain should vary in your application. After 16 posts we still do not know the original circuit or what its real problem is.

Maybe we should solve the problem with your circuit *before* assuming it is the component, changing it to something else you don't understand.

ak
 
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