Abstract: A multi purpose capacitive sensor suitable for indicating close proximity of a person to a surface along a large-size truck as well as along a medium-size painting or a pocket-size mobile phone is disclosed. The sensor comprises a voltage measuring device provided with a signal ground connected to a first pole of an oscillating voltage source that has a second pole connected to a signal input of the voltage measuring device. This input has a first capacitance to earth and a second capacitance to the signal ground. A third capacitance is exhibited to earth by the second pole of said voltage source. According to the invention, a prebias component is connected between the second pole of the voltage source and the signal input of the voltage measuring device.