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.
We can use this circuit to connect low impedance microphones and even small speakers used as a...
This alarm circuit is from a 1987 publication, however the components used are still modern. The...
In the figure we have the way to implement a comparator for voltages of opposite polarities. The...