This circuit was found in documentation from the 90s. The operational amplifier is NE5514, which is uncommon today. The configuration can be adapted to use modern components.
This simple field strength meter was found in a 1967 documentation. The transistor is germanium, and the...
This is yet another version of the light-controlled oscillator that can be found on this website. This...
Found in a 1969 documentation, this circuit for the 20 MHz band does not use a transformer. The circuit is...