Hi, im trying to build an eletronic system which autmatically detects a clooged heat exchanger. In order to do this i need to use two thermocouples which would measure the temperature, in tems of voltage, at teh intake and out take of teh heat exchange. I need some sort of voltage comparator which measures the difference in voltage between the two thermocoupples. Someone told me to use a voltage comparator circuit, but from what i see it is very limited to my use. Is there any type of circuit that can measure the difference between two voltages and give me a voltage that is proportional to this difference. I would greatly apprecaite anyones help in this matter as im am more oriened toward refrigeration.

Thanks
Kris

 

Unless you understand electronics, I recommend buying a temperature readout that can do what you need such as this http://www.omega.com/ppt/pptsc.asp?r...300&Nav=temm08 or http://www.omega.com/ppt/pptsc.asp?ref=DP26&Nav=temm03 from Omega. They can display the temperature difference between two temperature sensor inputs and can sound an alarm when a limit is reached.

 

I've used some of this Omega stuff - works great and a great company.

What output are you looking for - binary as in clogged or not clogged? Digital or analog voltage proportional to temperature difference? You can use a comparator fine with a trimpot for calibration if you or another knowledgeable person can fiddle with it and recalibrate each time you replace the thermocouples but if you are looking for a more modular approach that is simple to operate you will be time and money ahead going with the Omega stuff.

 

I think an op amp used differential amp or comparator would work.