I've looking to find the *cheapest* solution for interfacing J-type thermocouples to a MCU. The idea being to create a multi-therocouple input block that will be attached to a PC or DRO to display readings. The block will be split into about 10 input pairs or channels. What is not so important here is the actual temperature reading in degrees but the delta shift between each of the input pairs over time, although any reasonable approximation of the actual temp would be a nice.
From what I have found trawling the boards & google it looks like I have 2 or maybe 3 possible options, instrumentation op-amps hooked to ADC pins or a bunch of those fancy max66xx spi chip's @ 6-15 GPB ea. :shock:
I did however uncover this thread: https://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=32138&highlight=thermocouple
I am really interested in giving it try myself but an a little unsure of the input filtering, what is best RC, LC, both? Could a transistor be used as an active filter/pre-amp here?
Really just looking for some general direction here, am I just wasting my time with that idea? If so, any recommendation on suitable op-amps ~1.00 GBP? If not then are there any other possibilities I might have missed?
Note it does have to be for thermocouples, not thermistors or PT100/1000 etc.
Thanks for reading.