Below pictured is the basic circuit im working with, NCT is apparently pretty much a variable pot resistor.
The measuring point ive added. According to the manual for my car, the sensor is provided with 5v by the ECU and it reads the return voltage.
The Sensor decreases resistance with increasing temperature.
However when I measure the voltage at illustrated point, I get lower voltage at higher temp, and higher voltage at lower temp, the inverse of what expected…
What am I missing here about the behavior of this circuit ?
Best Answer
Most likely you are reading the detected voltage into a computer or MCU. The slope of the voltage graph with respect to temperature should be of little concern because it is so easy to "invert" the detected temperature by subtracting the reading from a constant that is the equivalent of the 5V level in your system.