This is a commercial circuit from the year 1958. Transistors are germanium types and transformers and coils are hard to fild today. The circuit is destinated to the reception of medium wave 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...