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 found in an American documentation from 1970. We can increase the number of...
The presented circuit allows to control the valve of a tap. The positioning of the emitter and the...
I found this circuit in an old British magazine from 1976. It is possible to test operational...