Found in a 1968 Novel Electronics Circuit, this circuit compares two light intensities using common LDRs as sensors. Transistors can be modern PNP equivalents.
In the figure we have a circuit suggested by National Semiconductor, using an operational...
For experiments with ionization chambers and Geiger valves this circuit generates high voltage from...
We found this circuit in a 1979 documentation, but it can be changed to use more modern...