Found in a 90s Popular Electronics, this circuit allows to select the operating ranges between short waves and VHF. MOSFET is uncommon today.
This circuit is from a 1968 documentation using one of the first integrated circuits available at the...
This circuit was found in a 1965 General Electric documentation. SCRs and unijunction may be...
This precision circuit can be implemented with other operational ones. We found it in a...