Electric OU: MOSFETs: How do they WORK ? Part 8: Putting feedback to use
Here I use the same components as the last video to make a simple, neat little airflow sensor. The NTC thermistor is positioned so that the bulb warms it, but with a gap in between. Then the potentiometer is adjusted to give a low brightness to the bulb. Now the system is a sensitive “thermometer” that can be used to measure the airflow between the NTC and the bulb. More airflow means less heat transfer to the NTC and the brighter the bulb, and vice versa. The voltage drop across the NTC (in other words the voltage on the gate of the mosfet) is a sensitive, repeatable set of numbers that correspond to the airflow parameters. Make an electric candle using this circuit, blow on it to … light it up! Your grandkids will be amazed. Other small minds are likely to be quite amazed by this impossible video demonstration, as well.