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.
In the figure is a diagram of a basic alarm with CMOS circuits and transistors obtained from a...
In the figure we have a circuit for an adjustable regulator with operational. The operator...
With the appropriate choice of C1 and C2 it is possible to divide the frequency of a rectangular 3 V...