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.
This low frequency circuit was found in documentation from the 1980s. The values of R and C...
This source for devices for automotive use was found in a 1985 documentation. The power...
Found on Popular Electronics in the 1980s, this circuit detects a change in air pressure using a...