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.
We found this circuit with 5.3V zener in a Philips publication from the 60s. The op amp could be a...
This circuit provides signals in phase with the input and with the phase inverted. The circuit was...
This sensor with two transistors triggers a relay according to the supply voltage. The power...