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 low current parallel or shunt type regulator was found in documentation from the 60's. The...
This circuit is found in a 1975s documentation for radio amateurs. It was developed to recognize a...
The displayed relay operates with an audio signal applied to the input. The transistors can be...