This circuit works as both an injector and a signal follower. We found it in the May 1994 issue of Electronics Now. The Z1 headphone must be high impedance.
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...