This old automotive circuit was found in an August 1971 Radio Electronics magazine article. The transistor is a Darlington transistor rated for the wattage of the bulb.
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....