This variable frequency oscillator with the 4093 was found in a Popular Electronics from the 90s. The table gives the component values for various frequency ranges.
This circuit, from an old publication from the 1970s, can be made with silicon transistors like...
We find this circuit in documentation from the 1980s. The triac and diac are of conventional types...
The purpose of this circuit is to convert a short-lived pulse into a negative rectangular pulse. The...