The instrumentation-amplifier tag has no wiki summary.
9
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4answers
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When is it an instrumentation amplifier (In-Amp) and not an operational amplifier (Op-Amp)?
I've seen a number of different configurations for instrumentation amplifiers, including 2 opamp versions. This
is also one. But it's just a differential amplifier preceded by input buffers. ...
6
votes
1answer
294 views
Why is my instrumentation amplifier's gain non-linear?
I am using an AD8226 instrumentation amplifier as the pre-amp in a circuit which uses a micro fuel cell oxygen sensor to measure oxygen content in a gas stream. The pre-amp is configured in single ...
5
votes
3answers
548 views
Instrumentation Amplifier - how to use it correctly
I am trying to perform some measurements based on a special technique used to detect corrosion in rebars of concrete bloc. The idea is to measure the potential difference between an electrode and the ...
5
votes
3answers
1k views
Op-Amp Input Resistor?
I'm reading through the datasheet for the TL064, which contains this figure on page 16:
This is of course an instrumentation amplifier that apparently uses an inverting amplifier's output instead ...
4
votes
3answers
906 views
Why use a three opamp instrumentation amplifier?
This TI application note shows this typical instrumentation amplifier (InAmp) with three opamps (p.4):
Further down the page the following two opamp InAmp is shown:
The former is more common ...
4
votes
2answers
115 views
subtract two AC voltages with instrumentation amps
I'm implementing the so-called "3 omega technique", where a thin metal line is excited with a sine current. The metal has a high TCR which causes a 3rd harmonic oscillation, and I need to measure the ...
3
votes
3answers
257 views
Very low frequency instrumentation amplifier
I'm trying to choose an instrumentation amplifier for very low frequency signals (seismic monitoring).
The trouble I'm finding is that on many of the data sheets, they only give response curves down ...
3
votes
1answer
52 views
Understanding common mode vs output voltage graph for instrumentation amps
What are limitations on the design imposed by this graph? Say, if I want my output to span 0V - 3.3V, does this mean that I should position my input signal at 2.5V?
edit: InAmp in question is ...
3
votes
2answers
690 views
How to Read Wheatstone Bridge negative voltage with Arduino?
I have a half bridge setup with strain gages and a INA126 to amplify the voltage. I can read the voltage fine when the lever is bent one way, but when beding the lever in the opposite direction I ...
3
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1answer
450 views
Drift and “flipping” in Instrumentation Amplifier reading thermistor
Disclaimer: I only have about 2-3 months of semi-intensive electronics experience.
Note that the chip (to the left of the Arduino, is Analog Digital's AD623 Instrumentation Amplifier) Datasheet ...
3
votes
1answer
509 views
Amplification of load cell signal with AD623 IC
I am trying to amplify the signal from a load cell using an AD623 instrumentation amplifier.
Please refer to http://www.instructables.com/answers/Amplifying-load-cell-signal-with-AD623-problem/
for ...
3
votes
1answer
157 views
MCP6N11 reference voltage problem
I am using the MCP6N11-010 in a current sensing circuit (Battery charger). i would like the output of the INA to show the difference in inputs starting from 0v going up to VDD but cant seem to get the ...
3
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2answers
144 views
Charge Model vs Voltage Model for Piezo Electric Sensor
The following document describes signal conditioning circuits for Piezeoelectric sensors. I was interested in knowing which model should I use when designing signal conditioning circuit for ...
2
votes
3answers
350 views
Error in this explanation of instrumentation amplifier?
On this webpage I read an explanation of an instrumentation amplifier:
The negative feedback of the top op-amp causes the voltage at Va to be equal to the input voltage V1. Likewise, the ...
2
votes
4answers
526 views
Simple op-amp differential amplifier
EDIT: Thanks everyone, I got it to work:
Now if only I could accept multiple answers...
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Is the output of this op-amp circuit linear in input voltage? The last equation \$A = ...
2
votes
2answers
201 views
Instrumentation Amplifier with Common Mode Feedback output
I'm currently attempting to design a small circuit that takes in a differential signal at < 4mv. I want to amplify this by around 1000 times.
I was reading up on Instrumentation Amplifiers, and ...
2
votes
2answers
293 views
Load Cell Amplifier AD620
I know AD620 is an old part but it is available at my place. I intend to develop a Load Cell amplifier. Load cell is 2mV/V. I am planing to use AD620 for it. Following are my calculations:
...
2
votes
0answers
348 views
Voltage Fluctuations in Arduino-opamp-thermistor circuit [closed]
I'm working on a board that takes measurements of voltage off a thermistor through an Arduino and amplified by an opamp (really an instrumentation amp AD623), also there are two potentiometers. See ...
1
vote
2answers
139 views
Instrumentation amplifier
I am using an instrumentation amp (http://www.linear.com/product/LT1168), and I am a bit confused why it is giving me a output voltage that I am not expecting.
I am pretty sure, I am doing something ...
1
vote
3answers
76 views
Economical thermocouple amplifier circuit
I'm looking for the most economical circuit that reasonably accurate circuit for amplifying the voltage produced by a thermocouple (so it can be read by an ADC). For the sake of argument, component ...
1
vote
1answer
98 views
Read-out circuitry for resistive biosensor
I have a biosensor. It's resistivity changes while sensing the analyte I want.
Resistivity of biosensor is around 10 Ohms.
I normally use Keithley 2400 sourcemeter for experiments. I apply a constant ...
1
vote
1answer
259 views
Phase shifting the common mode signal from an instrumentation amplifier
I was looking at the AD620 instrumentation amplifier data sheet. I'm looking at the ECG practical application on there (circuit shown below). Pins 1 and 8 of the instrumentation amp go through a ...
0
votes
1answer
100 views
Instrumentation Amp Voltage issue
Thanks for your help on the previous question. I set up my wheatstone bridge to pins 2 and 3 of the amp. When I use a voltmeter, I see differences over the bridge as a function of resistor change. ...
0
votes
3answers
407 views
Is is OK to drive AD620 with +-5V and expecting the output range up to 3.3V?
I'm using AD620 with STM32. So I want AD620 output up to be 3.3V. As 5V is easy to obtain, I want to drive AD620 with +-5V. Is that OK? Could a 5.5V driven AD620 generate 3.3V output? What about ...
0
votes
2answers
157 views
RFI/AC Filter Rejection for Instrumenation Amplifiers
I'm attempting to measure the voltage developed across a very long piece of cable (upto 500m bundle). The issue is that the cable picks up a lot of noise from nearby radio stations and also has a 50 ...
0
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1answer
566 views
Arduino analog input from an amp that uses a reference pin?
I am currently using an instrumentation amp (AD623AN) that uses a reference pin. I want to connect the analog output from the amp to my Arduino Ethernet so that I can measure it. How do I wire it up ...
0
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1answer
112 views
What is the reference pin on an instrumentation amplifier used for?
Happy new year all!
I'm wondering how to correctly use the reference pin on an INA128 Instrumentation Amplifier. Is there a way to use this pin to eliminate negative voltages (i.e. do a voltage ...
0
votes
2answers
764 views
Strain Gauge with Instrumentation Amplifier question
I have a problem making a circuit like this working
I got it from this TI application note. For testing purposes I have set:
\$R4=R2=R3=R1=47 \Omega\$
\$ Rf = 10 k\Omega\$
\$Rg= 26.70\Omega\$
...
