Only for reference this is a circuito f a commercial receiver of the year 1958. The circuit uses coils and transformers hadr to find in our days. The circuit is destinated to receive MW stations.
This simple 555 biofeedback circuit was found in the December 1983 issue of Radio Electronics...
Found in a 1969 EDN, this high current circuit, not indicated in the documentation, uses...
This tester for common unijunction transistors is nothing more than a low frequency oscillator...