This trip switch circuit was found in a Popular Electronics from the 90's. The frequency basically depends on C1 and R1.
This monostable circuit uses one of the two flip-flops available on the CMOS 4098 integrated...
This shield circuit for PC was found in an English documentation from 1996. The current of the...
This sophisticated digital timer was found in a 2002 documentation. Since CMOS integrated circuits are...