Abstract: An electric circuit is to be incorporated in a pointing device (such as a computer mouse) which is used in combination with a data processing system (such as a computer) so as to reduce the energy consumption of the pointing device without affecting the original functions and efficiency thereof and thus permit the pointing device to fit into a system wherein electric consumption is of vital importance. The electric circuit includes a timing control circuit and a noise-suppressing sampling circuit which controls the operation of the energy consuming elements of the pointing device according to the movement of the pointing device. The noise-suppressing circuit can distinguish movement signals from noise signals, thus suppressing the interference due to noise and further reducing the energy consumed by the pointing device.