INA114P Instrumenatation amplifier builiding manually

[rahulchauhan]

Hello Guys ,


I tried searching INA114P in local indian markets but was unable to get those , i am in realy urgency as my project submission date is near .

Finally , i decided to make the INA114P Inst. Amp. with my hand on circuit board . Here is the circuit diagram for same .






I just wanted to ask the name of three op amps used in INA114P , i googled the same but was unable to find it . Please help me asap so that i can start off my project .


Also please tell the alternative for TLC277p if any . I would be very thankful to edaboard if i get my answers .


Thanks,
Rahul,

- - - Updated - - -

Please help me , i am in a real urgency . I thought edaboard to be the best for asking this query and i haven't got any reply yet .

 

[LvW]

For my opinion, you can use any opamp - preferrably a chip with 3 or 4 opamps onboard.
Most important is the selection of 4 equal resistors for the last stage (not necessarily 25 kohms).

 

[rahulchauhan]

Thank you LvW , it helped but can you please tell me if i can use AP358 as a replacement for TLC277 .

 

[LvW]

Thank you LvW , it helped but can you please tell me if i can use AP358 as a replacement for TLC277 .

I didn`t check the data sheets very carefully - however, I see no reason why such a replacement should cause any problems.

 

[FvM]

I just wanted to ask the name of three op amps used in INA114P , i googled the same but was unable to find it.

Yes, because INA114 is a monolithic IC, not assembled from individual parts.

The question can be answered in two ways:
- It 's easy to build a basic three OP instrumentation amplifier circuit, you can do with any general purpose OP at your reach.
- If you want to achieve similar performance as INA114, you need components with sufficient specification regarding offset voltage and drift, input current etc. A halfway competitive replacement would use precision amplifiers like OP07 and maximum 0.1% tolerance resistors for the second stage.

You didn't tell about any INA114 specifications essential for your application, so we can't determine if it's nearer to the first or the second case.

 

[FvM]

I realized, that your application is apparently the sourceforge openeeg input amplifier. Some additional comments about OP replacement related to this application:
- DC offset doesn't matter, because the circuit is essentially an AC amplifier
- noise is a critical parameter. But the circuit isn't particularly noise optimized. LM358 or LM741 will involve higher amplifier noise than INA114, but not very high, so they can work in this regard
- LM741 is specidied for a minimal supply volrage of +/- 5V. It not guaranteed to work with 5V single supply voltage of the openeeg project.