This circuit was found in a 1967 General Electric documentation. Tunnel diodes can oscillate at very high frequencies. These are not currently easy to obtain components.
This circuit is from an Argentine publication from 1973. It generates a 100 kHz signal from a...
This filter was found in a 1975 American technical publication. The filter can be of any type and...
This circuit was found in a 90s American documentation. The circuit uses still common components...