I did a thing today.
My Thermocouple came in finally. Pics show my test setup. I just turned the stove on for a few seconds and then back off. The temp would rise and settle. Then, I shot the temp at the base of the spark plug to see what the head temp was.
Recorded the voltage displayed w/the temps on the way up (slowly increasing heat to not crack the stove top) and then recorded the temps and voltage on the way back down as the head cooled.
Voltages were lower on the way up because the heat wasn’t fully conducted into the thermocouple as the head temp was rising. I wanted an average of those values.
So, my numbers are:
200*F - 2.6mV
250 - 3.6
300 - 4.8
350 - 6.0
400 - 6.9
450 - 7.6
(these values are about 1.25mV off from listed values for K type thermocouple. I assume my non-calibrated multimeter and IR thermometer are to blame)
I want to make a tiny LED bar right under my speedo that goes: Blue, Green, Green, Yellow, Orange, Red. Corresponding to the temps listed above. Or something along those lines. You get it.
So, do any of you electrical engineers know what transistor or component I would need to turn on a circuit with 2-8mV?
I am envisioning building a test rig with variable resistor that I can adjust to turn on a amplifying transistor thing at say ~ 4.8mV and then measuring resistance of that. Then using plain old resitors in the actual build. Repeating that process for each LED/temp.
Does that make sense? Anyone out there think they can help me do this? Or know an off the shelf LED guage that might operate at this voltage range?