This circuit is from a 1967 documentation. It makes use of varicap and diode tunnel in addition to currently uncommon FET. It serves as a reference.
The circuit shown in the figure selects signals modulated at a certain frequency. This frequency...
The circuit presented was obtained in the National Semiconductor's Linear Applications Handbook of...
We found this circuit that uses a thermistor as a sensor from the 1991 Electronics Experimenter Handbook....