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 circuit was found in a Radio Electronics magazine from November 1992. The components are from...
This circuit was found in a 1969 Mullard publication. The transistor may be the modern equivalent...
This simple expandable circuit was obtained from a Popular Electronics from the 80's. The supply...