This circuit for RF measurements at 200 MHz was found in no documentation two years 80. At a sensitivity of 1V peak and the components used are still common in these days.
This circuit was found in a 1992 publication, using an operational amplifier not very common...
This is a amplifier for XTAL high impedance earphones or piezoelectric types. Current drain is...
This circuit is from the LM111 manual of the 1980s. The component no longer exists, but...