This circuit was found in an 80's Electronic Engineering. The circuit uses a multivibrator with neon lamps and an optical coupling system.
This circuit was found in a Popular Electronics from the 90s. The circuit uses general purpose...
Found in Raytheon's 1960s transistor circuit manual, this circuit employs the CK722, one of the...
This encoded lock circuit with alarm for use in homes was found in a publication from the 90s. The...