Quote:
Originally Posted by ImaginativeFig
why does it work? Is the liquid gas that much cooler than the air above it? ....
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No, but as long as the NTC is in the gas (fluid), it is liquid cooled. Once it is out of the gasoline, it is vapor cooled. The current going through it, warms it up. Since it is not cooled by liquid anymore, it becomes much warmer than when it would be submerged. Then, more current will flow through, it will become even warmer etc. and the LED lights up.
I wouldn't want some hot resistor in my gas tank, though...
And I have no idea what the resistors in series are for (parallel to the LED branch), and I wonder what the resistor parallel to the LED is for, that one is probably to keep the LED from gently shining when the NTC is still submerged.