The sensors in this circuit that triggers when the temperature goes out of a certain range are common diodes. The circuit is from the 1991 Reista Electronics Experimenter's Handbook.
This Colpitts oscillator with JFET has the amplitude of the signals stabilized by a diode. The...
This circuit is from European 90s documentation. The integrated circuit used is not very common...
This circuit of an old publication makes use of SCRs that admit modern equivalents. The frequency...