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.
In the figure we have a typical polarization circuit for MOSFETs with a high impedance...
Found ina 1970 American documentation this fast-reading circuit uses a photodiode. Transistors...
Found in a 1970's Radio Electronics, this circuit uses a triac to switch loads on the AC network. This...