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 counterphase circuit is from a 1973 publication, and can work with mains voltages or 12 V....
This circuit can be used to directly control direct current loads or higher alternating current loads...
The acquisition of data, from a transducer, so that these data can be converted to digital form...