Found in 90's Electronic Engineering this circuit can be used to measure phase angles between two signals from 0 to 180 degrees. The components used admit modern equivalents.
This circuit, found in a 1958 magazine, is for reference only, since the components are not easy...
Found in Popular Electronics this circuit triggers an SCR and lights an LED when the location of...
This OF-1 LO oscillator was found in a 1980s American documentation. The transistor can be any...