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 was obtained in a Motorola manual, but it applies to almost any operational...
Found in a 1970 EEE this circuit emulates a zener diode whose voltage can be set to R2. Power...
This circuit different from the timer was found in an English publication from 1978. The circuit uses...