Using an LDR as a sensor, this circuit is from the Radio Electronics magazine of December 1984. The operational amplifier is the 741 and the source must be symmetrical.
This circuit was found in the October 1994 issue of Electronics Now magazine. The 40446 IC is a...
Found in a 1967 EEE, this circuit generates a constant amplitude signal, stabilized by a zener...
This circuit is from the November 1974 issue of Radio Electronics magazine. The capacitor...