Obtained in a 1968 Electronics World, this circuit uses transistors from the time and the sensor is a common LDR. The component values are for scales from 0.01 to 100 foot-candle.
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....