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 obtained in a 1974 documentation. It shows how to use a JFET as a low intensity...
Schmitt Triggers convert a signal of any waveshape in square signals or pulses. The circuit shown...
This circuit was found in a 1992 publication. The critical component is the photodiode, but...