hello, i am using t type thermocouples for the measurement. am looking for a instrumentation amplifier for the same. i found ad595 is suit for the this type of thermocouples. but the temperature limit for this one is 0-50 degree celsius. for my application the temperature is 20-100 degree celsius. then i found ad849x for j and k type thermocouples..can i use this for t type?,,also is there any special amplifier for t type for the range of 20-100 degree celsius..
T-type and K-type thermocouples require very similar cold-junction compensation voltages. For this reason, I recommend that you use either the AD8495 or AD8497, depending on the ambient temperature…
Yes, you can use a multiplexer for your application. You can check this thread for more information.
I hope it helps!
Because you are using multiple thermocouples, you also have multiple reference junctions. You can transform these junctions into a single junction by using an isothermal block as in the…
thank you krisf..that circuit will be very helpful to me..
can i ask one question?..maybe its not valid, but i have doubt....my question is
- even if the amplifier contain cold junction compensation, did i need to make reference junction as shown in the circuit ( isothermal block)
- can i use the same circuit for the AD8497 amplifiers? also the same multiplexer?
Sorry for the delay in response.
Because you are using multiple thermocouples, you also have multiple reference junctions to deal with. Putting these junctions in an isothermal block (as shown in the link that I gave you) ensures that the cold junction compensation of the AD8497 compensates for the thermocouple directly underneath the IC. The isothermal block effectively cancels out the voltages at the other references junctions eliminating sources of error in your measurements. I would recommend that you keep this in your circuit.
You can use the same circuit for the AD8497, and I will need to get back to you on the multiplexer.
thank you krisf...i will move with the circuit as the figure..am looking for the multiplexer,otherwise i will go with ADG507
What would be the parameters of the resistors and capacitors for the emi filter?