This circuit with 4 transistors can receive signals in 6 shortwave bands. The circuit is from a Radio Electronics from May 1958. The output is for high impedance headphones.
Other series operationals such as the LM258, LM358 and LM2904 can be used on this circuit of the...
This circuit was found in old American documentation. It is a Wien bridge with the component...
This circuit is from a 1974 publication, but it can be easily assembled using more modern...