This circuit uses an unusual PLL, the 4046 CMOS. We found it in the October 1994 issue of Electronics Now. The circuit also uses a 4093 gate as a trigger.
This configuration was found in a publication for radio amateurs in 1975. It is a signal strength...
This circuit was obtained in a 1986 documentation consisting of an active frequency divider for...
With this name, we found this electronic stethoscope with a coal microphone in a 1957 Raytheon...