[AR] Re: Best Practices for Measuring Engine Temps with a Thermocouple
- From: David Weinshenker <daze39@xxxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Fri, 18 Oct 2013 20:26:40 -0700
David W. Schultz wrote:
> On 10/18/2013 09:08 PM, Norman Yarvin wrote:
>> Nevertheless, that voltage source doesn't have infinite ability to
>> source current; it's not quite _that_ magical. And if you have a
>> situation where two nominal "voltage sources" are fighting each other
>> (as you would if you had one junction near the inner wall and one near
>> the outer), their relative ability to source current is what
>> determines the resulting voltage (and thus the measured temperature).
>>
>
> The junctions do not source the current. The current is the result of
> heat flow in the conductor. You get a voltage output because the
> thermocouple wires have slightly different properties and generate
> slightly different voltages.
As I understand it the actual voltage is developed in the thermal
gradient along the wires. The junction itself is an electrical
connection to force the "far" ends of the wires to be at the same
voltage.
-dave w
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