This noise limiter for low intensity signals was found in a 73 magazine for radio amateurs from the 90's. The circuit is for signals from 10 mV to 1 V amplitude.
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...