[Amps] 8877 blower requirement -airflow switch

[Steve Thompson]

I've used a ptc thermistor - the sort that changes from low to high 
resistance abruptly at a set temperature. Run some current through it so 
it self heats, the airflow cools it so it stays below the trip point. 
The thermistor is about the size of a match head, so the mechanics are easy.

Many years ago a friend tried a variation on this - putting the sensor 
in the output air so it tripped if the air got too hot, whether that was 
from lack of flow or excess dissipation.

Steve