can't find any relevant youtubem pictures of the correct diagram or write up so far. spent hours looking, very tired of it. I knew that it's not going to be as straight forward as getting a issopro or other typical gauges as I used to get. I just want to try something new. Obviously that comes with a learning curve.

 

I hear ya and I like that you went for it. Is it possible that they can work without power being added? can you hook them up on the bench and hit them with a torch and see if it registers?

 

I did try it with the probe in a boiling oil pan in the kitchen. it did not move. temp might be too low. I'll torch it tonight. It still defies everything I know about physics. electricity is not generated by high temperature along, no matter how high. Temperature differential can indeed generate electricity.

 

did more reading and came across this, very interesting. It's from some experts in the field. It might just work w/o external power. If it does register when I torch it tonight, what will still puzzle me is how does it get power to do the cold junction electrical compensation. can't wait to find out.

"How to measuere temperature with a Type K ThermocoupleA thermocouple circuit contains the two alloy junctions, wire sand connectors and a voltage measuring device. When the two junctions are experiencing different temperatures, measurable current flows through the circuit. The current is related to the temperature differential. Because the measurement is relative, one of the temperatures must be known in order to calculate an absolute temperature. In early thermocouples, one junction was kept at 0° C by immersing it in an ice water bath. Today, one of the junctions, the "cold junction," is electrically compensated to maintain a standard. The other junction, the "hot junction," is exposed to the environment to be measured.

Collecting data from a type K thermocouple

A Type K thermocouple can be connected to a voltmeter for simple data collection. In this case, the output is a voltage, and the reader has to convert the voltage level to temperature using a conversion formula. To record data, the thermocouple can be connected to a data logger or a data acquisition system to store collected data. In these cases, a conversion circuit or a software operation can be used to calculate the temperature using the voltage output."

 

 

 

Hmmm do you have a small airport nearby? You could go ask their mechanic(s).

 

A thermocouple/pyrometer probe generates electricity when heated, it's not a resistor that varies with temperature. The gauge/meter connected to it will translate the voltage to a temperature reading.

 

That what I found out. when I heated it up with a torch the needle did not move. Maybe I did not heat it hot enough, afraid of burn it.

 

If you're using propane I think you'd have to work pretty hard to burn it, remember, it's good for 1250* or more.

 

Alright, I'll heat it harder tonight. I was thinking 1200F is only about 600C, 1600F 800C. that's why I did not burn it hard.

 

Thermocouples produce D.C. voltage. We are talking about millavolts here. 1000 mv = 1vD.C.
I'd be shocked it a Pyrometer thermocouple produced anything over 400mv, likely much less.

 

 

The little pilot light of a furnace or oven makes enough juice to open the gas solenoid so moving a needle seems like nothing.