Sensor amplification.

Thread Starter

superkayko

Joined Sep 28, 2022
1
Im trying design a thermocouple circuit to measure temperature over a certain range. The thermocouple used produces milliamp voltage. Im using an op amp with a +Vsat of 5V and a grounded -Vsat.

The problem im having is the increments of temperature measured by the thermocouple only produce a small current and if i increase the gain of the op amp to the point where the Amplified increments are significant enough to measure accuratly I quickly reach saturation. and if I decrease it to the point where the point im not reaching Vsat. The l lowest output value of the op amp over my required range is around 3V.

In essence I want the op amp to work between 0 and 5V and consequently have the amplified thermocouple voltages be amplided over this range.
 

Audioguru again

Joined Oct 21, 2019
5,158
When powered with +5V and 0V, some old opamps have inputs that do not work above +3V or work lower than +3V.
Use a modern "rail-to-rail" opamp that has inputs that work up to the positive supply voltage and work down to 0V.
 
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