Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
A circuit is disclosed for separating or detecting the presence of two voltage or current signals which are superimposed on a common line. As shown in the drawing, current IR1 is passed through transistor Q1 to LED1 (light-emitting diode) when the voltage across R1 is less than voltage VD1 across diode D1. When VR1 exceeds VD1, the transistor is cut off and the current is passed through LED2.