The configuration shown allows to obtain a high voltage gain for FETs. FETs can be BF245 or MPF102. The circuit is from the 1977 National Semiconductor FET Databook.
The transistors are 2N918, 2N3464 and other RF equivalents of the time for Q1. For Q2, 2N3399, 2N2894...
This circuit, which can be used as a shield, was found in a 90s Electronic Design. The circuit...
This interesting intercom circuit was obtained from an Argentine publication from the 1970s....