This circuit was obtained from the Encyclopedia of Electronic Circuits volume 5 of 1995. The circuit uses the 4001 CMOS to obtain hysteresis in the sensor feedback.
This circuit with JFET was obtained in a book on FETs of 1989. The circuit is still current since...
This is one of many possible circuits for the LM3914 IC as an audio indicator. The trim pot has...
This old slide projector control circuit was found in an 80s Hands On. The circuit uses modern...