We found this light relay circuit in year 2000 documentation. The relay is 6 V and the circuit includes a power supply. It can be used to control various devices from the incident light in the LDR.
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....