A control device suitable for synchros comprising three stator windings. The device comprises four circuit branches with the inputs of the first and the second branches interconnected to receive a first voltage from the ends of the stator windings of the synchro transmitter and with the inputs of the third and the fourth branches interconnected to receive a second voltage from the ends of the stator windings of the synchro transmitter. Two adder elements supply control voltages to the stator windings of the synchro receiver. Two inputs of the first adder are connected to the outputs of the first and the third branches, respectively and the two inputs of the secnd adder are connected to the outputs of the second and the fourth branches. These branches have transfer functions in the form sin (.alpha.+.phi.1), sin (.alpha.+.phi.2), sin (.alpha.+.phi.3), sin (.alpha.+.phi.4), respectively, wherein .alpha. represents the information supplied by a digital element and .phi.1, .phi.2, .phi.3, .phi.4 represent the differentphase shift angles. Used to display the position on the instrument panel of aeroplanes.