The present invention concerns an electrical circuit for generating an analog electrical signal depending on the heat loss of a resistive element (3), characterised in that the said resistive element (3) is connected into a wheatstone bridge (4) supplied at one of its diagonals by the intermediary of a transistor (10) whose base (11) is connected to the output of a high gain amplifier (12) which has its inputs (13, 14) connected to the other diagonal (15, 16) of the bridge (4), the said bridge comprising an adjusting potentiometer (17), the emitter voltage (30) of the said transistor (10) supplying the bridge and constituting the said signal. The invention can be applied to the measurement of the level of a liquid (2) in a container (1), the resistive element (3) being of elongated shape and disposed vertically in the container. <IMAGE>
