Fault protection of a variable differential transformer (VDT) excitation circuit

摘要

An excitation circuit includes an operational amplifier, a transistor circuit, a switch, and a pull-down resistor. The operational amplifier receives an excitation input voltage at a non-inverting input and provides an operational amplifier output. The transistor circuit receives the operational amplifier output and provides a transistor circuit output. The transistor circuit output is connected to an inverting input of the operational amplifier. The switch is connected between the operational amplifier output and the transistor circuit. The switch is opened to disconnect the operational amplifier output from the transistor circuit. The pull-down resistor is connected between an output of the switch and ground, wherein the pull-down resistor turns off the transistor circuit when the switch is opened.