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.
Below are two frequency filters for receivers using crystals. The crystals must have the frequency of...
Found in Popular Electronics from the 90s, this circuit has 7,500 ohm of input impedance. The circuit...
In this circuit the signal from the phototransistor is amplified by a Darlington stage and then...