Abstract: A timer mechanism for controlling a thermostat having a control shaft, the mechanism comprising: a frame, a synchronous motor mounted in the frame, a first and second lever pivotably mounted on the frame so as to be able to take an operative and an inoperative position, cam motion transmission means operatively connected to the said motor so as sequentially to pivot the said first lever from its inoperative to its operative position, while pivoting the said second lever to its inoperative position, and from its inoperative to its operative position, while pivoting the said second lever to its operative position, first transmission means operatively connected to the said motor and controlled by the said first lever to rotate the said control shaft in a first direction when the said first lever is in its operative position, and second transmission means operatively connected to the said motor and controlled by the said second lever to rotate the said control shaft in the opposite direction of rotation when the