Found in a 1968 Novel Electronics Circuit, this circuit compares two light intensities using common LDRs as sensors. Transistors can be modern PNP equivalents.
Indicated for scanning circuit applications, we found this generator in a Radio Electronics from the 80s....
This circuit tests crystals up to a few megahertz with ease. The circuit is from a 1977...
Found in documentation from the 70s, this circuit uses an operational one from that time. It goes for...