Thermal reading Instrumentational amplifier

[TBlumenthal]

Hello,

I am currently a college student who was tasked with creating a instrumentation amplifier via multi sim that will take in two inputs from some form of thermal reading device like a thermocouple and apply a large gain to create a sin wave for the user to read.

I have created a base line for what I am going for but I'm not getting a nice transient analysis graph that shows the two sine wave inputs and then a smooth output wave. this is my first time trying to using thermal noise sources and not sure if I have the necessary values for them or if I should even use them to begin with to represent a small signal from a given thermal reading. Id like to represent multiple temperature levels if I can, or at least have a way to get a output based off a given temperature that can be changed and simulated to give a result.

Some feed back on my design and suggestions would be greatly appreciated.

Here's what I have so far:

[GGoodwin]

Hi TBlumenthal,

Typically, temperature is a variable that changes very slowly with time. Of course there are several situations where temperature rise or fall rapidly. On the other hand, dealing with sinusoidal variation of temperature may belong to special undertakings. What I like to convey is, if your goal is to be able to create circuits that will help you get familiarized with temperature-measuring circuits you should pursue the more general ones.

Then, while a thermal noise source generates output that depends on temperature, the variation will have random characteristic. So it's unusual to expect a sinusoidal waveform from a thermal noise generator.

A widely used thermocouple signal-conditioning circuit is Wheatstone Bridge followed by an Instrumentation Amplifier or, in some cases, a Difference Amplifier with lower input resistance. You need to make additional research on this subject and auxiliary but important functions such as cold junction compensation, linearization, calibration, etc.

Best regards,

G. Goodwin