A capacitive proximity switch is device that senses presence of metallic or non-metallic objects. The internal circuit consists of an oscillator, threshold detection stage and an open capacitor formed by two metallic electrodes. The oscillator is inactive when target is away from the switch surface. When target is near to switch surface, change in the net capacitance formed by the switch open capacitor and the target. The circuit begins to oscillate and change in the oscillation amplitude is detected by threshold detection.