Found in American documentation from 1968, this circuit has an acute cut-off of the frequency to which it is tuned and which depends on RC. Transistors may be modern equivalents of general use.
This circuit is from an ancient American documentation. The coil is frequency dependent and the...
This circuit was found in the March 1994 issue of Electronics Now magazine. The circuit uses a...
This circuit was found in a Popular Electronics from the 90s applying to common automotive...