Found in a 1968 Novel Electronics Circuit, this circuit compares two light intensities using common LDRs as sensors. Transistors can be modern PNP equivalents.
General Electric suggests this circuit in a 1980s documentation. The operational of the time is...
This is the receiver from the previous alarm system. The circuit is from Radio Electronics, April...
This stable 20 MHz oscillator was suggested by the National Semiconductor's Linear Applications Handbook...