This 1950s audio amplifier uses output tubes of type 1625 in its output stage. The Class B circuit provides a few watts of power and uses transformers that are not readily available today.
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....