This circuit was suggested by Linear Technology in documentation from the 90s. The circuit applies to modern operators with modern transistors.
This circuit, which can be used as a shield, was found in a 1980s documentation. The circuit can be...
We found this circuit in a 1991 publication. It indicates when an analog phone line is busy by...
This 6 V battery charger was found on a 1987 Hands On Electronics. Rc determines the charging...