2-WIRE ISOLATED REMOTE LEVEL CONTROL
Original Publication Date: 1990-Jun-30
Included in the Prior Art Database: 2004-Apr-05
Xerox Disclosure Journal
The circuit illustrated in the Figure fulfills a need for a remote level control of a system with isolation from the output. By using only 2 wires, preferably coaxial (e.g. RG196AAJ) for noise immunity, human input by a potentiometer 10 and indication of output by an LED 12 are achieved. The potentiometer 10 allows infinite level control from "off' to "on7,. An opto-isolator 14 provides a suitable resistance change, e.g. from about 7 KR to 700 KS2, for driving solid state switches, analog to digital converters, audio amplifiers, power amplifiers, motor controls, light controls, and the like, while isolating the operator from the controlled output. Various suitable sensors or inputs 16 and 18 can be added to the front end of this remote control for additional control. Examples of typical sensors include thermistors for temperature control or photoresistors for light control. Due to the gain of the transistor 20 (e.g. 2N49191, long distances of several hundred feet between the input and output are possible with high noise immunity.