In the starting while reading about thermocouples everywhere they say they are inexpensive but the ic i gone through costs more than 1000 Rs each.. and i don't think it is inexpensive to include the microcontroller to read and the k type thermocouple wire and display. if i included all of them the total cost is no near to the inexpensive.
so i did look for the alternatives in net, they give me so much circuit where i didn't understand one of them so i come back to the maxims max6675.
and again i wondered what if i wanted to measure the temperature at two or more different places with only including cost of k type thermocouple wire.. i think it looks interesting what i wanted to do is
take a max6675 ic that do cold junction compensation and gives the temperature of the thermocouple wires connected to them, i want to multiplex the two or more temperature measurement wires and pass to the max6675 one at each time to measure the temperature.
Wait a minute..
if I connect an another IC between thermocouple wires and Max6675IC doesn't it form a another 2 junctions which may be result garbage values at the display.....
So
it won't work
I concluded it.. But Suddenly i went through something like thermocouple law of intermediate metals
According to the Thermocouple Law of
Intermediate Metals, illustrated in Figure below,
inserting any type of wire into a thermocouple
circuit has no effect on the output as long as both
ends of that wire are the same temperature, or
isothermal.
So if i assume that both IC's i.e multiplexer IC and thermocouple cold junction compensation ic is at same temperature, we can measure various temperatures at different locations using single Max6675 IC.
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