This circuit is from the Motorola LinearDatabook of 1990. It shows how it uses the LF355, 356 and 357 operational capacitive loads. The power supply must be dual.
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....