We found this circuit in the 1989 Radio Electronics Experimenter. The circuit uses common components, and the thermistor is supposed to determine the value of the trim potentiometer.
Found in a 1990s American technical brochure, this circuit is intended for alarms that use as...
This control for bass, midrange, and treble was found in the March 1995 issue of Electronics Now...
Found in a 1965 General Electric documentation, this circuit is intended to control a 150 W lamp...