NE602 Crystal Oscillator (CB26005E)

This oscillator reaches 50 MHz with an overtone crystal. The circuit is from Electronics Now magazine from February 1997.

Contrast Meter (CB26202E)
This circuit for photography uses was found in the Electronics Experimenter Handbook Special...
Lock Timer (CB5980E)
It is like to the previous circuit with a lock that keeps the LED on at the end of the timer. The...
Dual Sensor (CB21521E)
This circuit, with two operationals, was obtained from an old American publication. Operational...