This light meter circuit was found in 80's Radio Electronics. The circuit uses a milliammeter as an indicator and the sensor is a common LDR. The power supply must be symmetrical.
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....