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Switzerland
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Hy

How can I connect a  T-Thermocouple ([ch8722]185C to +300C) to arduino?
Maxim doesn't sell those kind of converter or did I miss something?

Thx
Geko
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Nope, Maxim only has an interface for the common K-type.  I haven't seen one for a T-type (and please let me know if you find one!).  IIRC Analog Devices makes some t-couple interface ICs as well, but I haven't searched their product line for details.

A thermocouple gives a small voltage indicating a temperature differential; in order to use it effectively you need an amplifier (to make that small voltage larger and easier to measure), and you need a reference temperature.  You'll also need an ADC, but he Arduino has one of those built in.  You'll also have to do some math to convert those two voltages into an absolute temperature.

Hmm, I think I have a Hobo datalogger around somewhere that has a T-type on it.  If I can find it, I map pop it open and see what kind of goodies it has inside.

-j

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Switzerland
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Would be very nice!

In another thread you've mentioned that you've used a balloon for something. Did you also measure the temperature at high altitude?


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Geko
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Yes.  It is typical to see -40C (which is also -40F, weird/common point in the two scales) on balloon flights to ~100k ft.  It is common to see temperatures below that, down to -70C.

Flights are generally on the order of 3 hours (2 hours up, not quite 1 hour down).  The inside of typical payloads don't get below 0C, due to insulation and self-heating (e.g. multiple 78xx voltage regulators, radios, etc).

-j

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Greenwood, Indiana
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There is a circuit here that should make it 1v to 5v out
http://www.5bears.com/circuits.htm
He has one that does cold junction compensation and such.

He also has a precision mV output circuit.

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