Originally, this circuit was created to monitor the liquid level in the reservoir of a car's windshield wiper. The circuit is from documentation from the 90s.
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...