Abstract: A bridge circuit for measuring or use in a temperature-responsive servo-mechanism. A chain of four or alternatively five resistors is connected between power supply rails, an inner two resistors of the chain being shunted by the track of a potentiometer. A balancing potentiometer is connected directly across the supply rails and has its wiper connected to one side of a balance detector through a high value resistor. The signal to be measured is applied between the chain of resistors and the other side of the balance detector. There is a resistive connection from the wiper of the first-mentioned potentiometer and the resistor chain to the end of the high value resistor nearer the detector. The signal to be measured is derived from a resistance-type or thermo-couple temperature sensor. Reference junction compensation for the latter is described.

Abstract: An electromechanical transducer comprises first and second links pivotally connected to a base, an electrical resistance element in the form of a track mounted on the base and a wiper arm mounted at one end of the second link and slidingly engaging the track. The first link and the second link are so coupled that pivoting one link is operative to pivot the other link and the angle through which the second link pivots is substantially greater than the angle through which the first link pivots. By suitable selection of the shape and/or the resistance profile of the track, the angular movement of the first link may be arranged to be a particular linear or non-linear function of the resistance tapped by the wiper arm. A control unit incorporating the transducer is also described.