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 circuit with JFET and Unijunction was found in an ancient American documentation. The...
This metering bridge circuit uses one power supply only. The operational ones depend on the...
We found this configuration in the 1964 RCA transistors manual. As indicator loads in each stage,...