This circuit was found in the August 1972 issue of Radio Electronics magazine. The circuit generates 4 types of signals as can be seen in the diagram. The maximum frequency is around 20 kHz.
We found this circuit with a Q factor of 25 in the Linear Applications Handbook by National...
Found in a 1967 Electronics World, this preamplifier uses an integrated circuit from that time,...
This circuit uses a special 1950's RCA strobe tube. It can be built with equivalent components for the rest...