Found in Popular Electronics from the 90s, this 1.5 A power supply can supply voltages selected by a switch. The splitter resistors determine the output steps.
This is the basic configuration of a function generator with the 8038 integrated circuit (uncommon...
This filter for receiving audio in telegraphy was found in a magazine 73 for radio amateurs, in an...
This circuit amplifies VHF signals in the two-meter range and is very critical, especially...