Found in American documentation from the 90s, this circuit triggers a buzzer with a Sonalert-type oscillator when the temperature of the sensor reaches a certain value set in R2.
This circuit is from an 80's electronic component manual. It has the way to simulate an inductor...
This is the receiver for the previous circuit found in the November 1991 Radio Electronics...
This circuit was found in a Popular Electronics documentation from the 90s. It is possible to switch...