next topic »

[on:]

Can anyone tell me if I can hook-p a type k thermocouple to an arduino uno?

[Reply #1 on:]

Can anyone tell me if I can hook-p a type k thermocouple to an arduino uno?

Not without external circuitry to handle getting cold reference junction information. The best way to utilize thermocouples is to use the purpose designed ICs made for them.


Lefty

[Reply #2 on:]

http://www.adafruit.com/products/269

[Reply #3 on:]

Thermocouple output voltages are tiny (microvolts per degree) - far too small to use directly with Arduino analog inputs.  Themocouple ICs handle both the compensation for the cold-junction temperature and the precision amplification needed to produce usable voltage levels - some include an ADC as well so only need digital interfacing.

[Reply #4 on:]

Go with what Jack pointed out. Its self contained and uses a digital readout. Google MAX31855... there are lots more at possibly better prices... if you don't mind waiting for a slow boat from China.

There are several  scripts ready to go. Just remember that the digital inputs from the Arduino have to be 3.3 volts, not 5 volts.

[Reply #5 on:]

Google MAX31855

The older MAX6674 and MAX6675 both work with K types, they work at 5V, and there is working arduino libraries (at least, there's a library for one that can be modified for the other).

I think someone even has a shield available.

-j

[Reply #6 on:]

The older MAX6674 and MAX6675 both work with K types, they work at 5V, and there is working arduino libraries (at least, there's a library for one that can be modified for the other).

I think someone even has a shield available.

I have not seen one ,  but you can buy adapters to 8 Pin SOIC to DIP8 Adapters. They are a pain to solder, but they do work.

http://www.futurlec.com/SMD_Adapters.shtml

[Reply #7 on:]

AD595 in DIP as used here
https://www.sparkfun.com/products/81
www.arrowelectronics.com

http://components.arrow.com/part/detail/52071S5444913N2771

[Reply #8 on:]

ok now my simple question is, what if i just want to read to the nearest 100c... do i need an amp?

[Reply #9 on:]

Take a look at the AD595 datasheet, see what level of input it is expecting from the thermocouple.
The '328P can take in 1.1V/1024 as the lowest reading, about 1mV. Probably not reliably, will need a couple of mV for a reliable reading.

[Reply #10 on:]

Take a look at the AD595 datasheet, see what level of input it is expecting from the thermocouple.
The '328P can take in 1.1V/1024 as the lowest reading, about 1mV. Probably not reliably, will need a couple of mV for a reliable reading.

Looks like type K's are around 4mV per 100C. It should work.

http://srdata.nist.gov/its90/download/type_k.tab