Volt drop compensation for output transducer - uses positive feedback from primary winding to input amplifier and negative feedback to inverting input of operational amplifier

摘要

The primary winding of the transducer is excited by an operational amplifier and the object of the proposed circuit modification is to keep the primary winding voltage exactly proportional to the amplifier input voltage. Non-linearities occur due to primary winding chmic resistance and distortion introduced by the presence of a magnetic core. A positive feedback resistor is added between the primary winding and the reference voltage, and a connection taken to the non-inverting input of the amplifier. The values of the inputresistor, negative feedback resistor, and positive feedback resistor are chosen such that for k = Rn/Re = k'. Rc/Rxthe value of k' lies between 1 and 1.1. In this range almost complete compensation for resistance volt drop and harmonic distortion is achieved.