Found in a 1968 Novel Electronics Circuit, this circuit compares two light intensities using common LDRs as sensors. Transistors can be modern PNP equivalents.
This circuit was found in documentation from the 80s. The components are from the time, but the...
This circuit is from Philips' 70s documentation. Transistors can be replaced by modern...
This circuit was found in a 2006 publication. It uses discrete components and CMOS that are still...