This peak detector has a memory to prolong the response. The circuit is from American documentation from the 1980s. The supply does not have to be symmetrical.
This voltage regulator was obtained in the SGS manual of linear integrated circuits of 1982. The...
Of course, the design indicates a specific application for a touch switch. Thus, analyzing the...
In the figure we have the way to obtain the Exclusive-OR function with 1 transistor. The circuit...