The difference between this circuit and the previous one is that it uses PNP transistors. The circuit is from Radio Electronics magazine from July 1968. The frequency depends on R1 and C1.
This circuit was found in the 1991 Electronics Experimenters handbook. It can be used to display RGB...
This circuit uses sensors to determine who is the first to cross the end line. The circuit was...
Found in a General Electric documentation from 1970, this circuit consists of a relaxation...