We found this circuit in an old American publication from the 1980s. Transistors can be general-purpose types like the BC548, and the tuning frequency is given by the L and C components.
This circuit is from a Radio Electronics from April 1965. It uses an incandescent lamp, and the...
This circuit was found in a 1968’s publication and uses germanium transistors. The characteristic...
This is a single IC voltage regulator that can acts in the range from 1.2 to 20 V. Output currewnt is up to...