The instrumentation-amplifier tag has no wiki summary.
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1answer
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AD620 In-Amp, single 5v supply, reference pin affecting gain
Given the datasheet here, I can't explain my observations with my AD620AN test circuit.
The circuit:
Supply: +5v / 0v (Well regulated)
1k potentiometer across the supply, with the wiper going to ...
2
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1answer
42 views
Thermocouple signal conditioning - how to deal with low output swing margin of amplifier?
I have this thermocouple conditioning circuit. Let's say my gain is 100. Minimum low level for AD8237 is 20mV. As K type thermocouple outputs 40uV per 1C, I will have 4mV per 1 degree C.
This ...
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2answers
116 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
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1answer
60 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 ...
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3answers
97 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 ...
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2answers
318 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:
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1answer
99 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 ...
3
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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 ...
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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. ...
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1answer
118 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 ...
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2answers
705 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 ...
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1answer
306 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 ...
3
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2answers
149 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 ...
3
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1answer
525 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 ...
1
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2answers
140 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 ...
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4answers
530 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 = ...
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1answer
263 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 ...
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2answers
158 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 ...
2
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2answers
203 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 ...
3
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3answers
258 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
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1answer
457 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 ...
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0answers
352 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 ...
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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 ...
5
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3answers
555 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 ...
0
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1answer
570 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 ...
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3answers
409 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 ...
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3answers
928 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 ...
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2answers
774 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\$
...
2
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3answers
358 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 ...
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4answers
2k views
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. ...
