This circuit periodically reverses the rotation of a motor to change the position of eggs in an incubator. The circuit is from Electronics Now magazine, May 1995.
Other operational amplifiers series operatives, such as MC34072, MC34074, MC35071, MC35072,...
This circuit was obtained in a 1967 General Electric documentation. It is a relaxation oscillator...
This circuit is from the 1983 Intersil Databook. This is a configuration that is still used today...